These are some spacecraft designs that are based on reality. So they appear quite outlandish and undramatic looking.
In the will appear designs that are fictional, but much more breathtaking. Obviously the spacecraft on this page are all NASA style exploration vehicles, they are not very suited for interplanetary combat (well, most of them at least). For slower-than-light star ships, go. Many of these spacecraft have a table of parameters. You can find the meaning of many of them. Numbers in black are from the documents.
Consumer Product Matters has put together this CPSC Navigator page for our readers to easily find what they need at the Consumer Product Safety Commission. This is from A Nuclear Cryogenic Propulsion Stage for Near-Term Space Missions. Abbreviations in table: 25 klb f NTP Engines: 111.2 kN.
Numbers in yellow have been calculated by me using the document numbers, these might be incorrect. NCPS Mars Mission Core stage (C) Engine Isp, sec 900 Inert Mass, mt 44.99 x3 25 klb f NTP Engines 12.32 x3 External Radiation Shields 6.45 Tank inert (w/ everything else) 26.22 Usable LH 2 Mass, mt 41.64 RCS Usable Prop Load, mt 17.05 Boil-off to ullage, mt 0.20 Stage Length, m (engines, RCS, I/F) ~22.2 Approx. Effective LH 2 PMF / λ 0.48 In-line Tank (I) Inert Mass, mt (w/ everything) 28.59 Usable LH 2 Mass, mt 66.40 RCS Usable Prop Load, mt 5.51 Engine Isp, sec 900 Stage Length, m (incl. RCS & I/F) ~21.2 Approx.
Effective LH 2 PMF / λ 0.70 Saddle Truss & Drop Tanks, 1 ½ (D) Inert Mass, mt 38.35 Saddle Trusses (w/ everything) 7.73 Drop Tanks (w/ everything) 30.61 Usable LH 2 Masses mt 103.30 RCS Usable Prop Loads, mt 8.58 Boil-off, mt 1.54 Engine Isp, sec 900 Stage Length, m (incl. RCS & I/F) ~33 Approx. Effective LH 2 PMF / λ 0.73 Payload (stocked) 51.85 MPCV (CM+SM, no prop) 14.49 Payload RCS/Truss/Canister 14.14 Pre-TMI Crew, mt 0.79 Less mass exp. Prior to TMI, mt (-25.95) Mass Schedule Core stage wet mass total, mt (on pad) 103.68 In-line Tank wet mass total, mt (on pad) 100.50 Saddle Truss & Drop Tanks wet mass total, mt (on pad) 151.76 Payload wet mass total, mt (on pad) 80.48 Mars stack interim total 436.43 Pre-TMI, mt -25.16 Total TMI Stack Mass, mt 411.26 This is from. Abbreviations in table: • 25 klb f NTP Engines: 111.2 kN Pewee-class nuclear thermal engines • PMF = • λ = • PMF / λ = propellant fraction to payload fraction ratio • RCS = • I/F = I'm not sure but has to do with docking structure used to connect stages • MPCV = (Orion spacecraft) • CM+SM = Orion plus Orion • TMI = Trans-Mars Insertion, first burn at mission start to leave Terra orbit NASA experimented with nuclear thermal rockets with Project Rover, which ran from 1955 through 1972. It is really hard to work with spacecraft that use the 'N-word' and which may spread the 'R-word', but they are far too useful to leave on the shelf.
Twice the specific impulse of the best chemical engines, and thrust values which make ion drives look like hummingbirds. So in 2011 NASA iniatied the Nuclear Cryogenic Propulsion Stage (NCPS) project. This spacecraft design uses nuclear thermal rockets for a Mars mission. THE MISSION • click for larger image. Ideal Specific Impulses of Martian Propellants Temp Carbon Dioxide (CO 2) Water (H 2O) Methane (CH 4) CO or N 2 Argon 1400 K 162 222 460 162 110 2800 K 283 370 606 253 165 3000 K 310 393 625 264 172 3200 K 337 418 644 274 178 3500 K 381 458 671 289 187 The easiest propellant to manufacture is liquid carbon dioxide. It can be produced from the Martian atmosphere using just high pressure (690 kPa) with no cryogenic cooling needed (a 30 horsepower pump will do, requiring 25 kW, or 80 kilowatt hours per metric ton). The Martian atmosphere is about 95% CO 2 so it is not like there is any shortage of the stuff.
Other propellants have superior performance but are much harder to manufacture. Carbon dioxide has enough specific impulse to boost the NIMF from the surface of Mars into low Mars orbit, so the designers figured it was good enough.
It also has enough Isp to hop the vehicle from point A to any other point on Mars. As I mentioned each metric ton of propellant sucked out of the atmosphere takes 80 kilowatt-hours, and the propellant tank holds about 302 metric tons total.
About 24,160 kilowatt-hours to fill it. How long it takes to fill the tank depends upon how many kilowatts the power source can feed the pump. • Power can come from the nuclear reactor in the rocket engine, if you make it. It would produce about 100 kilowatts of electricity (kWe).
Advantage: The report says this will fill the tank in 12 days (my slide rule says it will take 10 days at 100 kWe for 24,160 kWH). It would also require zero mass for the power supply, since the rocket engine has already been accounted for.
Disadvantage: is that operating the reactor while the ship is landed with spray deadly radiation all over the landing site. This makes it difficult for the crew to do things like disembark, embark, and linger near the ship. • Power can come from a. It can produce about 25 kWe (averaged around the clock to take account of nighttime) Advantage: no radiation Disadvantage: The report does not mention how long it will take to fill the tank but presumably 1.2 as much time as the RTG: 60 days (my slide rule says it will take 40 days at 25 kWe for 24,160 kWH. 30 kWe / 25 kWe = 1.2). The array is about 3,500 m 2 and has a penalty mass of 8.8 metric tons. It also takes three crew members about 2 days to set up and break down, making the total delay about 44 days between flights.
• Power can come from an. It can produce about 30 kWe. Advantage: practically no radiation. It has a penalty mass of 4 metric tons, about half of the solar cell array. Unlike the solar cell array it requires no setup or breakdown time. The report says this will fill the tank in 50 days (my slide rule says it will take 34 days at 30 kWe for 24,160 kWH), which is less than the solar cell array. Disadvantage: It has a penalty mass of 4 metric tons as compared to the bi-modal engine.
It will take many more days than the bimodal engine. The paper decided the RTG was the optimal solution. A reactor temperature of 2800 K (I sp 283) is required to boost the vehicle from the surface of Mars into high orbits (ΔV 5,685 m/s). But only 1400 K (I sp 162) would be needed for Mars to Mars hops (ΔV 3,254 m/s). Apparently the exhaust velocity (V e) is assumed to be about 2,587 m/s From Top to Bottom: • Storage Dome • Flight Deck • Habitation Deck (crew living quarters, supports a crew of three for more than one year) • Mechanical Deck (machinery to liquifly atmospheric carbon dioxide) • Propellant Tank • Nuclear Engine The nuclear engine has a shadow shield on top composed of steel, boron, and lithium hydride to protect the crew from radiation when the reactor is operating.
A secondary toroidal propellant tank surrounds the reactor to protect crew walking on the surface when the reactor is idling. There is a second radiation shield right under the crew, to protect them from reflected off the ground during landing.
The reactor elements will need, since when carbon dioxide is heated to high temperatures inside the reactor it will oxidize the heck out of everything it touches. Reactor elements designed for liquid hydrogen propellent won't work, they will rapidly erode and spray powdered glowing radioactive death while the reactor stops producing power and the ship plummets out of the sky.
This is from Robust Exploration and Commercial Missions to the Moon Using NTR LANTR Propulsion and Lunar-Derived Propellants (2017),. NLTV stands for Nuclear Lunar Transport Vehicle.
The basic idea is if we set up in-situ resource utilization facilities on Luna which can produce Lunar-derived propellant (LDP) — specifically Lunar Liquid Oxygen (LLO 2) and Lunar Liquid Hydrogen (LLH 2) — what sort of spacecraft can this support? LLO 2 can be obtained from or volcanic glass, both LLO 2 and LLH 2 can be obtained from. The original didn't know about polar ice, so it figured that hydrogen would have to be shipped from Terra while oxygen could be harvested from lunar volcanic glass. The discovery of lunar polar ice means nothing has to be shipped from Terra. The amount of lunar hydrogen and oxygen is estimated to be many billions of tons. The availability of liquid oxygen makes the obvious choice of basing it around (LANTR) propulsion. This is a using liquid hydrogen propellant, but with a liquid oxygen afterburner which allows the engine to.
So it can trade thrust for exhaust velocity (specific impulse) and vice versa. The gear shifting is due to the afterburner, the nuclear reactor operates at the same power level regardless of what gear is used. By judicious use of gear shifting, the total mission burn time of the engine can be cut in half. This doubles the number of missions the engine can perform before the engine comes to the end of its lifespan. The LANTR can shift gears. See how as the Delivered Isp goes down, the Thrust goes up. An O/H (oxygen/hydrogen) Mixture Ratio of 0 is a basic solid-core nuclear thermal rocket using pure hydrogen for propellant, or a LANTR with the afterburner turned off.
The higher mixture ratios are for a LANTR with the oxygen afterburner activated, with increasing amounts of injected oxygen. 1.0 lb f of thrust equals 4.45 Newtons The best a chemical propulsion system can do is about Isp of 450 seconds NAR is Nozzle Area Ratio The report figures that the initial industrialization of Luna will be done by non-LANTR, which will have to carry lunar landers along with the payload. This departs from LEO, but has to return to a 24-hr elliptical Earth orbit (EEO) because it just doesn't have the delta V to return to LEO. To give it that much delta V would require the ship's wet mass would have to almost double to 347.8 metric tons! Once industrialization starts, small amounts of lunar liquid oxygen (LLO 2 or LUNOX) will become available. This will allow lunar landers to be housed in the lunar base, so the SNRE spacecraft will not have to carry them.
This will allow the spacecraft to carry lots more payload. They still will have to return to EEO instead of LEO, though. When lunar industrialization becomes fully developed, larges amounts of LUNOX will become available and an orbital propellant depot will be established in lunar orbit. At that point the spacecraft's will be swapped out for LANTR engines, and the in-line liquid hydrogen tank swapped for a liquid oxygen tank carrying 46.5 metric tons of LO 2. Once the ship arrives in LLO, it will refill the liquid oxygen tank from the orbital propellant depot.
The refueling and the LANTR gear shifting will allow the ship to return to LEO and reduces the engine burn time from 50 minutes to 25.3 minutes. This doubles the lifespan of the engine. • Top ship is standard vehicle with SNRE engines Middle ship assumes that the Lunar base has advanced to the point that it can support a lunar landing vehicle, so the ship does not have to carry one Bottom ship has SNREs swapped for LANTRs, and LH 2 in-line tank swapped for a LO 2 tank because the Lunar base has advanced enough to supply unlimited LUNOX click for larger image In the above designs, all the LH 2 tanks carry 39.7 metric tons of liquid hydrogen.
The payload pallets are 2.5 metric tons each. One-way transit times to and from the Moon will be about ~72 hours. Sikorsky Skycrane These are two optimized LANTR designs. They share a common nuclear thermal propulsion system (NTPS), including the LO 2 tank (though the size of the LO 2 tank is different between the two). The one-way transit times to and from the Moon will be cut in half to ~36 hours. This will require the delta V budget to be increased by 25% from ~8,000 km/s to ~10,000 km/s.
The Crewed Cargo Transport has its own dedicated habitat module weighing ~10 t, plus a 4-sided, concave star truss that has attached to it four 1.25 t payload pallets. The LO 2 tank is smaller and customized for this particular application resulting in a lower Initial Mass In Low Earth Orbit (IMLEO or wet mass in 407 km altitude orbit) and LLO 2 refueling requirement (~35 t). The Commuter Shuttle carries a forward Passenger Transport Module (PTM) that contains its own life support, power, instrumentation and control, and reaction control system.
It provides the “brains” for the LANTR-powered shuttle which is home to the 18 passengers and 2 crew members while on route to the Moon. Arriving in Low Lunar Orbit (LLO, 300 km altitude), the PTM detaches and docks with a waiting “” Lunar Landing Vehicle (LLV) that delivers it to the lunar surface. From here the PTM is lowered to a “flat-bed” surface vehicle for transport over to the lunar base and passenger unloading. • click for larger image. Item Cargo Transport Commuter Shuttle Mission LEO⇒LLO⇒LEO Duration 36-hr “1-way” transit times Habitat Module ~11.2 t n/a Passenger Transport Module n/a 15.2 t Crew 4 2 Passengers n/a 18 Star Truss w/ 5 t payload ~8.6 t n/a In-line LO 2 tank ~86.6 t ~74.5 t LH 2 NTPS ~70.9 t IMLEO (wet mass) ~177.4 t 160.6 t Refueled LLO 2 ~71.6 t ~67.9 t Total Burn Time ~25.3 min All the missions start and end in LEO, with the mid-point being either Lunar equitoral orbit or Lunar polar orbit.
The polar orbit requires more delta V. “1-way” transit times range from 72–24 hours are considered. Faster transit times are avoided, because they preclude and thus are more unsafe.
Meaning if the engine malfunctions the ship goes sailing off into the wild black yonder and the crew dies a lonely death. MASS SCHEDULE ASCENT CAPSULE (2,386 kg) Structure 445 kg 227 kg Communication 95 kg Guidance & Control 102 kg 608 kg 240 kg Return Payload (Geological samples) 136 kg Crew (90 percentile) 318 kg Contingency 215 kg STAGE II (4,277 kg) Tanks & System 313 kg Engine 222 kg Propellant 3,742 kg STAGE I 10,210 kg Tanks & System 730 kg Propellant (9,480 kg) TOTAL ASCENT STAGE 16,874 kg The Mars Excursion Module is from a 1966 study by North American Rockwell. This was the first Mars lander designed after the bombshell from that astronomers had drastically over-estimated how dense the Martian atmosphere was.
They had figured it was a useful 85 hectopascals (hPa), in reality it was an almost worthless 6 hPa (just slightly better than a vacuum). By way of comparison Terra's atmospheric pressure at sea level is 1013 hPa. The poor prior design that was rendered obsolete by the low atmospheric pressure was the The low atmospheric blow Mariner 4 dealt to the scientist was just the cherry on top of the sundae. Much more serious was the photographs. The scientists knew there could be no chance of images of, but they were hopefull there would be some lakes and maybe even a or two.
The scientists got a sinking feeling in their stomachs, as they could almost see the Mars exploration program go swirling down the toilet right before their very eyes. Once the taxpayers saw these photos the NASA tax dollars would dry up. Mars looks like the freaking moon, for cryin' out loud! And NASA has already been to the moon. Been there, done that, got the T-shirt. No need to go to Moon part deux.
But NASA put a brave face on things, and proceeded to plan for a Mars mission anyway. Sadly, they were right. As I write this it is fifty years later and the movie is still science fiction, not a documentary.
That furry 'whumph' noise you hear is RocketCat doing a facepalm. Given the pathetic whisp of Martian atmosphere, NAR went with a classic gum-drop shape much like the Apollo command module for aerobraking purposes. For one thing all the expertise obtained from Apollo could be leveraged. Plus there was Terra's atmosphere conveniently located for heat shield test purposes.
Though I did read a suggesting that even with the gum-drop design the Martian atmosphere is not up to the task of aerobraking the MEM before it splats into the ground at hypersonic velocities. The report suggested that entirely new technologies are needed. In a genius move, NAR made the design modular. If you needed a lean and mean mission, you could remove some internal compartments, ascent propellant, and surface supplies to get the total lander mass down to 30 metric tons.
Or you could max it out. Or anything in between. The price of a low mass lander is that it could only support two crew for four days, and the mothership had to be in a low circular Mars orbit for both departure and return to the mother. The high mass lander needed lots more delta V from the mothership, but it could support four crew for thirty days, and the mothership could be in a high elliptical Martian orbit. You can also make a.
This can be used to land supplemental equipment, such as an extended-stay shelter, nuclear power module, or a huge Mars with fuel supply. From Definition of Experimental Tests for a Manned Mars Excursion Module NAS9-6464 (1967) • MEM has a mass of 49,437 kg when it separates from the mothership. The deorbit motors fire for about 200 m/s. Deorbit motor has a thrust-to-weight-earth of 0.4. The MEM starts falling out of orbit, and the deorbit motors are jettisoned. The MEM now has a mass of 46,078 kg.
• The MEM enters the Martian atmosphere at an angle of attack of 147°. It starts aerobraking, subjecting the crew to about 7 g's. When it slows to a mere 3.5, it pops a hypersonic drogue chute to stabilize then inflates a 18 meter diameter ballute.
This will slow the MEM down to Mach 1.5. • Once the MEM lowers to 3 kilometers of the surface, it jettisons the ballute. The plug in the heat shield over the descent engine is jettisoned. The descent engine is canted about 13° off center, because the MEM center of gravity is off center, because due to design consideration the MEM is not radially symmetric. Mostly because of that pesky crew quarters and laboratory.
• The conical section of the heat shield is jettisoned. The descent engine ignites and burns for 1,070 m/s to 1,450 m/s Δ V, depending upon whether the mothership was in a circular or elliptical orbit when the MEM detached. At this point the engine will have a thrust-to-weight-earth of 1.5 to 0.15. • The design managed to squeeze in enough extra propellant for about two minutes of hovering (about 457 m/s of Δ V).
Which could be a life-saver or something. Instead of hoving, the extra propellant can move the MEM laterally about 6.7 kilometers to an alternate landing site.
The design had six landing legs. In concert with the incredibly stable gum-drop shape, they could manage a ground slope of up to 15°. Actually the shape is similar to a no-spill coffee mug, and for the same reason. • The crew then frantically does as much Martian scientific research as they can cram into 30 days. The pressurized volume is 21.6 m 3 (14.4 is laboratory/living quarters, 7.2 is ascent capsule). 20% is taken up by equipment, leaving barely 4.3 m 3 per crewperson ().
• When it is time for departure, the descent stage becomes the launch pad (which stays behind on Mars), and the center becomes the ascent stage. It brings the crew and 136 kilograms of Martian geological samples back to the orbiting mothership.
It launches as Ascent Stage I. • When the Stage I tanks run dry, they are jettisoned. The ascent stage continues as Ascent Stage II.
The two stages have a combined Δ V of 6,200 meters per second. The ascent has five components. • Initial burn to 19 kilometer altitude (mothership circular: 4,206 m/s Δ V, mothership elliptical: 4,286 m/s Δ V) • Coast to 185 kilometer altitude • Burn to circularize orbit (23 m/s Δ V) • At appropriate time, burn to ascend for rendezvous (mothership circular: 168 m/s Δ V, mothership elliptical: 1,327 m/s Δ V) • Rendezvous with mothership at apoapsis • Total Δ V: mothership circular 4397 m/s, mothership elliptical 5,635 m/s • The ascent stage docks with the mothership using its (RCS). It has 100 meters per second of Δ V left for the docking at this point. The rest was burnt during the descent and ascent phases. The deorbit motors are the knot on the bottom. The descent engine is temporarily hidden behind the plug in the heat shield..
It is fed from fuel tanks in the descent stage. The ascent stage I is the external tanks. Their fuel is burned through the ascent stage II engine. When the stage I tanks run dry, 'staging' is by jettisoning the tanks. The ascent stage II is the internal tanks and the engine at the bottom.
From Final Report: Propellant Selection for Spacecraft Propulsion Systems, Volume II Missions and Vehicles (1968) The deorbit stage uses a beryllium solid rocket fuel with a specfic impulse of 300 to 325 seconds, a thrust of 133,500 to 204,600 Newtons, and a burn time of 48 seconds. The reaction control system was supposed to use (ClF 5) oxidizer with (MHF-5).
The latter is a devil's brew of,, diethyline triamine, acetonitrile, and hydrazine nitrate. Which is just as vile as it sounds.
It has a specific impulse of 336 seconds. The space shuttle used a more modern mix of monomethylhydrazine fuel with oxidizer. But nowhere near as bad. It also has a specific impulse of 336 seconds. The one joker in the deck was the specified fuel for the descent and ascent stages. It seems they couldn't quite get the Δ V they needed out of conventional liquid oxygen (LOX) and liquid hydrogen (LH2). With the the design had ( i.e., the tiny fuel tanks), LOX/LH2 could not even manage the 4,880 m/s Δ V required to reach the mothership in a low circular orbit, much less the 6,200 m/s Δ V required if it was in a high elliptical orbit.
The problem was that LH2 takes up a lot of room, but the MEM's fuel tanks are cramped. There wasn't room for enough LH2 even if the entire area was converted into one gigantic tank.
So they used FLOX and liquid methane (CH 4) instead. That can do 6,200 m/s Δ V easy because liquid methane is more than six times as dense as liquid hydrogen. So you can cram six times as much liquid methane mass into the same sized tanks.
Using FLOX instead of LOX makes up for the lower energy in methane. FLOX/CH 4 has a specific impulse of 383 seconds, compared to LOX/LH2's specific impulse of 449 seconds. LOX/CH 4 is lucky to get a pathetic 299 seconds.
What is I hear you ask? Why, just a simple mixture of liquid oxygen, and. Fluorine is beyond insanely dangerous.
It is incredibly, and will (some explosively). They don't call it ' for nothing.
The pious hope of the MEM designers was to contain the FLOX in tanks lined with nickel or something similar that would form a. The FLOX mix is 82.5% fluorine and 17.5% oxygen. Mixing liquid fluorine and liquid oxygen is actually relatively safe. For some odd reason those two will not chemically combine without some coaxing. If they do combine, however, you get the dreaded compound Dioxygen Difluoride. This is the compound with the chemical formula FOOF, which coincidentally is the sound your laboratory will make as it blows up. This is the most famous compound in Derek Lowe's hysterical list of (take a minute to read it, the article is a scream).
Another concern is that in a tank the fluorine and oxygen might separate. Then the engine would periodically be sucking pure fluorine, which certainly will not be doing the engine any good. Carrying entire tankfuls of ultra-corrosive flaming explosive death to Mars seems to be a questionable decision, to say the least. If the MEM lands a trifle hard and the tanks rupture, you won't have the basis for a re-make of. More like a large melted crater with a few odd pieces of corroded metal and polished skeleton bits at the bottom. At least the MEM designers saved mass on the ignition system. You don't need any.
FLOX/CH 4 is (because fluorine is hypergolic with almost anything). This is also a help when the ascent stage does staging, you can easily re-start the engines in mid-flight. I'm doing more research, but apparently the MEM design is so popular, that it was later redesigned just a bit to remove the need for liquid fluorine oxidizer.
This would involve removing equipment and increasing the size of the fuel tanks. From Definition of Experimental Tests for a Manned Mars Excursion Module NAS9-6464 (1967) The descent engine (blue) is canted about 13° off center, because the MEM center of gravity is off center, because due to design consideration the MEM is not radially symmetric. You can see the asymmetry above.
The blue circle with the astronaut in it is the laboratory/crew quarters, it is lighter than the green tank on the opposite side. • From Final Report: Propellant Selection for Spacecraft Propulsion Systems, Volume II Missions and Vehicles (1968) Click for larger image. • From Final Report: Propellant Selection for Spacecraft Propulsion Systems, Volume II Missions and Vehicles (1968) Click for larger image.
• From Final Report: Propellant Selection for Spacecraft Propulsion Systems, Volume II Missions and Vehicles (1968) Click for larger image. • Artwork by click for larger image • Artwork by click for larger image • Artwork by click for larger image • Artwork by click for larger image • Detail Artwork by click for larger image • Detail Artwork by click for larger image • Detail Artwork by click for larger image • Detail Artwork by click for larger image •. These are from Technological Requirements Common to Manned Planetary Missions: Appendix D by the space division of North American Rockwell (1965). They detail a s family of Planetary Excursion Modules (PEM). Here I will focus on the retrobraking PEMs, that is, the ones that use retrorockets to land because the target planets have no atmosphere to allow aerobraking.
These particular PEMs were intended for landing on Ceres, Vesta, Ganymede and Mercury. They are based on the with an on top of a. They are designed for a 30 day stay on the planetary surface, before returning to orbit.
They do, however, have Rockwell's fixation on using the insanely dangerous as an oxidizer, and the only somewhat dangerous (MMH) as fuel. The reason is that liquid hydrogen requires preposterously huge tanks, but if you use anything else the specific impulse goes way down. Unless you take the mad-scientist step of using FLOX oxidizer to make up for it. In the diagrams below, the Ascent Stage is pink, the Descent Stage is green, and the mission crew quarters is gold.
• click for larger image North American Rockwell 3-Crew Ceres-Vesta PEM Total Wet Mass 14,036 kg Descent Stage Descent Dry Mass 9,000 kg Descent Wet Mass 11,350 kg Descent Propellant Mass 2,350 kg Propulsion Chemical FLOX/MMH Propulsion I sp 333 s? Descent Engine Thrust 8000 N (835 kg-force) Descent Engine Mass 1.85 kg Ceres Gravitational Acceleration 0.28 m/s 2 Descent Start Acceleration 2.0 Ceres gravities Ascent Stage Ascent Dry Mass 2,280 kg Ascent Wet Mass 2,686 kg Ascent Propellant Mass 406 kg Ascent Engine Thrust 3,780 N (384 kg-force) Ascent Engine Mass 0.85 kg Ascent Cabin Volume 6.3 m 3 Ascent Cabin Diameter 2.44 m Ascent Cabin Long 1.83 m Crew Quarters Volume 14.0 m 3 Crew Quarters Diameter 2.44 m Crew Quarters Wide 3.96 m Airlock Volume 1.1 m 3 Airlock Diameter 0.915 m 3 Crew Quarters Volume (inclu. Airlock) 15.1 m 3 Total Crew Volume 21.2 m 3 Consumables (30 day, 3 crew) MMH 54.4 lbs/ft 3 FLOX 90.0 lbs/ft 3 Nitrogen 12.30 ft 3 295 kg Oxygen 10.00 ft 3 325 kg Water 8.86 ft 3 244 kg Food 5.63 ft 3 175 kg The mission crew quarters is merged with the ascent stage. Note the Descent Stage Dry Mass does not include the mass of the ascent stage. North American Rockwell 10-Crew Ceres-Vesta PEM Descent Stage Descent Dry Mass 18,100 kg Descent Wet Mass kg Descent Propellant Mass 4,700 kg Propulsion Chemical FLOX/MMH Propulsion I sp 333 s? Descent Engine Thrust N (1,675 kg-force) Descent Engine Mass 3.7 kg Ceres Gravitational Acceleration 0.28 m/s 2 Descent Start Acceleration Ceres gravities Crew Quarters Volume m 3 Crew Quarters Diameter m Crew Quarters Height 2.14 m Airlock Volume 1.41 m 3 Airlock Diameter 0.915 m 3 Crew Quarters Volume (inclu. Airlock) 66.0 m 3 North American Rockwell 10-Crew Ceres-Vesta PEM Total Wet Mass 27,800 kg Ascent Stage Ascent Dry Mass 4,530 kg Ascent Wet Mass kg Ascent Propellant Mass 815 kg Ascent Engine Thrust N (760 kg-force) Ascent Engine Mass 1.68 kg Ascent Cabin Volume 11.2 m 3 Ascent Cabin Diameter 3.06 m Ascent Cabin Long 1.94 m Total Crew Volume 3 North American Rockwell 10-Crew Ceres-Vesta PEM Consumables (30 day, 10 crew) MMH 54.4 lbs/ft 3 FLOX 90.0 lbs/ft 3 Nitrogen 980 kg Oxygen 1,080 kg Water 815 kg Food 590 kg A page appears to be missing from my copy of the document.
North American Rockwell 3-Crew Ganymede PEM Wet Mass 17,300 kg Descent Stage Descent Dry Mass 9,500 kg Descent Wet Mass kg Descent Propellant Mass 3,740 kg Propulsion Chemical FLOX/MMH Propulsion I sp 333 s? North American Rockwell 10-Crew Ganymede PEM Descent Stage Descent Dry Mass 28,100 kg Descent Wet Mass kg Descent Propellant Mass 7,500 kg Propulsion Chemical FLOX/MMH Propulsion I sp 333 s? Descent Engine Thrust 55,000 N (5,550 kg-force) Descent Engine Mass 12.3 kg Ganymede Gravitational Acceleration 1.428 m/s 2 Descent Start Acceleration Ganymede gravities Crew Quarters Volume 66 m 3 Crew Quarters Diameter 6.1 m Crew Quarters Height 2.14 m Airlock Volume m 3 Airlock Diameter 0.915 m 3 Crew Quarters Volume (inclu. Nuclear DC-X Propulsion pebble-bed NTR Propulsion LANTR NTR Specific Impulse 1000 s LANTR Specific Impulse 600 s NTR Exhaust Velocity 9,810 m/s LANTR Exhaust Velocity 5,900 m/s Wet Mass 460,000 kg? Kg Mass Ratio?
M/s Mass Flow? Kg/s NTR Thrust per engine 1,112,000 n LANTR Thrust per engine 3,336,000 n NTR Thrust total 5,560,000 n LANTR Thrust total 16,680,000 n NTR Acceleration 12 g? LANTR Acceleration 38 g? Payload 100,000 kg Length 103 m Diameter 10 m This is from a report called (2004). It is a single stage to orbit vehicle using a for propulsion. They figure it can put about 100 metric tons into orbit at a cost of $150 per kilogram.
You can read the details in the report. The single ferry tank is sized to contain 349,828 pounds of liquid hydrogen and has attached to its after-end, a thrust structure and four fast spectrum metallic-core nuclear reactor engines. Each of the four engines will produce 47,900 pounds of thrust so that with one engine inoperative, the initial thrust-to-weight ratio is 0.24. The dry weight of the nuclear stage is 71,658 pounds, which results in a stage mass fraction of 0.830.
The lunar shuttle, shown in docked position, employs the techique of receiving its propellant by the assembly of prepackaged modules in lunar orbit with the empty module being jettisoned on the lunar surface. The lunar shuttle propulsion system uses LOX-LH 2 propellants and is designed around a cluster of three 20,000-pound thrust engines. The lunar shuttle personnel module is of the segmented sphere configuration sized to accommodate a total of 30 men and having all expendables and time-dependent subsystems sufficient for a two-day mission duration.
One spaceship that could make the trip is now under study by Ling-Temco-Vought, Inc. For NASA and is show here as it debarks its 28 passengers into a landing craft for the descent to the moon's surface.
The tapered passenger-carrying nose of this ship (below, left) had departed from Earth three days earlier atop a booster. Once in orbit around the Earth, it had then hooked onto a 125-foot-long nuclear-powered ferry (the section carrying the American flag) that carried into the region of the moon. Having now attained a lunar orbit, the passenger section has swung down 17 feet on long tubular links, alowing a small spherical craft to hook on and load up the passengers for the 100-mile trip down to the moon. In the background at right a similar nuclear ferry also has lowered its passenger section and is about to receive a moon shuttle. Scientists say the passenger section could be used over and over again—for as many as 50 round trips.
Because of this reusability, space scientists estimate the eventual cost of maintaining a moon station at only $1 million per man per year. FLO surface habitat vehicle • Solid line is NERVA derived nuclear engine Dotted line is nuclear engine (CIS) click for larger image • Scaling data for the liquid hydrogen tanks show tank surface area, structural mass, and propellant capacity as function of total tnak length click for larger image • Shows the Initial spacecraft Mass in LEO (IMLEO) required to deliver the 96 MT payload into TLI, as a function of engine thrust level, for single and multi-engine designs. Each curve is a family of vehicles. The takeaway is that for a given total thrust level, multiple engine designs have a higher IMLEO, which is bad.
Also, each curve has a lowest IMLEO point, which is where you find the optimum engine thrust level click for larger image • This compares a nuclear stages with a chemical stage, to show how worthless chemical engines are. The basic chemical engine is that dot at the upper-right corner click for larger image. Is a 2002 study by the Embry-Riddle Aeronautical University for a reusable Earth-Mars cargo spacecraft utilizing a VASIMR propulsion system powered by an on-board nuclear reactor.
The report has lots of juicy details, especially about the reactor. Thanks go out to William Seney for bringing this study to my attention. RMBLR (Rotating Multi-Megawatt Boiling Liquid-Metal Reactor) 'Rambler' System. Fuel: Blocks with coolant channels UN+Moly alloy with Rhenium & hafnium, Primary coolant: Potassium, Reactor outlet temperature:1440K, power conversion: Direct Rankine, Specific Mass: 1-2kg/kWe @ 20 MWe assuming a bubble membrane radiator. • Attitude Thrusters on the Cargo Bay (two not shown) • The Two Stages of PARTS • The Cargo Bay unfolding • A Typical Truss Member (hinges not shown) • Solid Model VASIMR • Rotating Mult-Megawatt Boiling Liquid-Metal Reactor (RMBLR I) • Docking Mechanism Components • Docking Mechanism Components. • Pilgrim Observer Propulsion NERVA 2b Propulsion Uprated J2 chemical NERVA Specific Impulse 850 s J2 Specific Impulse ~450 s NERVA Exhaust Velocity 8,300 m/s J2 Exhaust Velocity 4,400 m/s Wet Mass? Kg Mass Ratio?
M/s NERVA Mass Flow 13 kg/s J2 Mass Flow 25 kg/s NERVA Thrust 110,000 newtons J2 Thrust 110,000 newtons Initial Acceleration? Kg Length 30 m + boom Diameter 46 m The Pilgrim Observer was a plastic model kit issued by MPC back in 1970 (MPC model #9001) designed. Many of us oldster have fond memories of the kit. It was startlingly scientifically accurate, especially compared its contemporaries (ST:TOS Starship Enterprise, ST:TOS Klingon Battlecruiser, ). The model kit included a just full of all sorts of fascinating details. NERVA engine design, mission plan, all sorts of goodies with the conspicuous absence of the mass ratio and the total delta-V.The kit has been, and those interested in realistic spacecraft design could learn a lot by building one.
If you do, please look into the, and alternate. Round 2 Models (the company who re-issued the kit) have some detailed kit building instructions. The Pilgrim makes a cameo appearance in Jerry Pournelle's short story ', in the role of the Boostship Agamemnon, and in Allen Steele's short story ' as the Medici Explorer. The design is interesting, and has a lot of innovative elements.
For one, it uses a species of to deal with the artificial gravity problem. It also uses to augment its radiation shielding, in order to save on mass and increase payload. This is done by mounting the NERVA solid core nuclear rocket on a telescoping boom. One major flaw with the Pilgrim's design is the fact that one of the three spinning arms is the power reactor. This means that all the ship's power supply has to be conducted through a titanic slip-ring, since there can be no solid connection between the spin part and the stationary part.
Another flaw is if you are going to all the trouble to put the NERVA reactor on a boom to get the radiation far away from the crew, why would you put the radioactive power reactors on an arm right next to the crew? Anyway, the Pilgrim is an orbit-to-orbit spacecraft that is incapable of landing on a planet. It has a ten man crew (four crew and six scientists), and has enough life support endurance to keep them alive for five years. It could also be used as a space station, in LEO, GEO, or lunar orbit. In launch configuration the NERVA boom is retracted and the spinning arms are locked down. In this configuration it is 100 feet long and 33 feet wide, which fits on top of the.
A disposable shroud is placed over the top of the spacecraft to make it more aerodynamic during launch. Level Gravity Level 6 0.05g Level 5 0.06g Level 4 0.07g Level 3 0.08g Level 2 0.09g Level 1 0.10g After launch, the shroud is jettisoned, the spinning arms deploy, and the NERVA engine's boom telescopes out. The spinning arm array has a diameter of 150 feet.
The arms will rotate at a rate of two revolutions per minute (safely below the ). This will produce about one-tenth Earth gravity at the tips of the arms (Level 1), which fades to zero gravity at the rotation axis. Not much but better than nothing. The spherical center section does not spin, a special transfer cabin is used to move between the spin and non-spin sections. One arm is the crew quarters, one is a hydroponic garden for the, and the third is a stack of advanced Space Nuclear Auxiliary Power (SNAP) reactors using Brayton cycle nuclear power units.
Astrotug The center section is divided into the Main Control Center at the top and the Service Section at the bottom. The very top of the Control Center has the large telescope, radar, and other sensors. By virtue of being mounted on the non-spin section, the astronomers and astrogators can make their observations without having to cope with all the stars spinning around.
Also mounted here is the antenna farm for communications and telemetry. The Pilgrim carries two auxiliary vehicles: a modified Apollo command and service module, and a one-man astrotug similar to the worker pods seen in the movie 2001 A Space Odyssey. They mate with Universal Docking Adaptors on the non-spin section. The chemical propulsion system consists of three up-rated J-2 rocket engines with a thrust of 250,000 lbs, fueled by liquid hydrogen and liquid oxygen.
The nuclear thermal propulsion system consists of one solid-core NERVA 2B, using liquid hydrogen as propellant. The NERVA has a specific impulse of 850 seconds, a thrust of 250,000 pounds, and an engine mass of 35,000 pounds (the fact that both the J-2 and the NERVA have identical thrust makes me wonder if that is a misprint). It uses a de Laval type convergent-divergent rocket nozzle.
The reactor core has a temperature of 4500°F. The core of the reactor is encased in a beryllium neutron reflector shell. Inside the reflector and surrounding the reactor core are twelve control rods.
Each rod is composed of beryllium with a boron neutron absorber plate along one side. By rotating the control rods, the amount of neutrons reflected or absorbed can be controlled, and thus control the fission chain reaction in the reactor core. There is a dome shaped on top of the NERVA to protect the crew from radiation. In addition, the NERVA is on a long boom, adding the inverse square law to reduce the amount of radiation.
And finally, the cosmic ray shielding around the crew quarters provides even more protection. Various attitude control and ullage rockets are located at strategic spots, they are fueled by hypergolic propellants. The mission will start in June of 1979.
Mission is an Earth-Mars-Venus-Earth swing-by. It will have a mission duration of 710 days, as compared to the 971 days required for a simple Mars orbiting round trip. This is done with clever gravitational sling-shots, and use of the NERVA 2B.
Mission starts with an orbital plane change to a 200 nautical mile circular Earth orbit inclined 23°27' (i.e., co-planar with the ecliptic). Transarean insertion burn is made with the three J-2 chemical engines (D+0). At this point the Pilgrim 1 becomes the Pilgrim-Observer space vehicle.
It will coast for 227 days. Then it will perform a retrograde burn with the NERVA to achieve a circumarean orbit (Mars orbit) with a periapsis of 500 nautical miles and a high point of 5,800 nautical miles (D+227). The Pilgrim-Observer will spend 48 days in Martian orbit (including several close approaches to Phobos). Then the NERVA will thrust into a transvenerian trajectory (D+275). It will coast for 246 days, including a close approach and fly-by of the asteroid Eros occurring 145 days after transvenerian burn (D+320).
The NERVA will burn into a circumvenarian orbit of of 500 nautical miles (D+521). It will spend 55 days studying Venus.
The NERVA will thrust into a transearth injection (D+576). It will coast for 140 days. Upon Earth approach, it will burn into a 200 nautical mile Earth orbit (D+710). The crew will be out shipped by a shuttle craft following extensive debriefing.
I did some back of the envelope calculations, and the numbers look fishy to me. An Earth-Mars Hohmann and Mars capture orbit will take a delta V of about 5,200 m/s. This is done with the J-2 chemical engine, and will require a mass ratio of 3.3. That is not a problem. The problem comes with the NERVA burns.
The Mars-Venus burn and the Venus-Earth burns have a total of about 14,800 k/s. With a NERVA exhaust velocity of 8,300 m/s, this implies a mass ratio of 5.9. I'm sorry but without staging you are going to be lucky to get a mass ratio above 4.0. The plastic model kit is allegedly 1:100 scale according to the kit instructions. However, that various parts are clumsily in different scales.
The 'arms folded mode' diameter is supposed to be 33 feet, to fit on top of a Saturn V, that is 1:127 scale. The rotating arms and the Apollo M are more like 1:144 to 1:200 scale. At 1:100 the arms have a deck spacing of a cramped 5 feet, the passage connecting the arm to the ship proper is only 2.5 feet in diameter, and the command module on the Apollo M is 20% smaller than the real Apollo CM. So the scale of the plastic model kit is a mess.
IBS Agamemnon Total ΔV 280,000 m/s Specific Power 39 kW/kg (39,000 W/kg) Thrust Power 1.1 terawatts Exhaust velocity 220,000 m/s Thrust 10,000,000 n Wet Mass 100,000 mt Dry Mass 28,000 mt Mass Ratio 3.57 Ship Mass 8,000 mt Cargo Mass 20,000 mt Length 400 m Length spin arm 100 m T/W >1.0 no IBS Agamemnon (Interplanetary Boost Ship) masses 100,000 tons as she leaves Earth orbit. She carries up to 2000 passengers with their life support requirements. Not many of these will be going first-class, though; many will be colonists, or even convicts, headed out steerage under primitive conditions. Her destination is Pallas, which at the moment is 4 AU from Earth, and she carries 20,000 tons of cargo, mostly finished goods, tools, and other high-value items they don't make out in the Belt yet. Her cargo and passengers were sent up to Earth orbit by laser-launchers; Agamemnon will never set down on anything larger than an asteroid. She boosts out at 10 cm/sec 2, 1/100 gravity, for about 15 days, at which time she's reached about 140 km/second. Now she'll coast for 40 days, then decelerate for another 15.
When she arrives at Pallas she'll mass 28,000 tons. The rest has been burned off as fuel and reaction mass. It's a respectable payload, even so. (ed note: in reality, the is about 10,000 newtons, not 10,000,000 like the Agamemnon is cranking out.) The reaction mass must be metallic, and it ought to have a reasonably low boiling point.
Cadmium, for example, would do nicely. Present-day ion systems want cesium, but that's a rare metal—liquid, like mercury—and unlikely to be found among the asteroids, or cheap enough to use as fuel from Earth. In a pinch I suppose she could use iron for reaction mass. There's certainly plenty of that in the Belt. But iron boils at high temperatures, and running iron vapor through them would probably make an unholy mess out of the ionizing screens. The screens would have to be made of something that won't melt at iron vapor temperatures. Better, then, to use cadmium if you can get it.
The fuel would be hydrogen, or, more likely, deuterium, which they'll call 'dee.' Dee is 'heavy hydrogen,' in that it has an extra neutron, and seems to work better for fusion. We can assume that it's available in tens-of-ton quantities in the asteroids. After all, there should be water ice out there, and we've got plenty of power to melt it and take out hydrogen, then separate out the dee. (ed note: 1,100 gigawatts burning about 0.014 kilograms of deuterium per second. For 30 days total burn time this will require about 36 metric tons of deuterium.) If it turns out there's no dee in the asteroids it's not a disaster.
Shipping dee will become one of the businesses for interplanetary supertankers. MAYDAY MAYDAY MAYDAY. THIS IS PEGASUS LINES BOOSTSHIP AGAMEMNON OUTBOUND EARTH TO PALLAS.
OUR MAIN ENGINES ARE DISABLED. I SAY AGAIN, MAIN ENGINES DISABLED.
OUR VELOCITY RELATIVE TO SOL IS ONE FOUR ZERO KILOMETERS PER SECOND, I SAY AGAIN, ONE HUNDRED FORTY KILOMETERS PER SECOND. AUXILIARY POWER IS FAILING. MAIN ENGINES CANNOT BE REPAIRED. PRESENT SHIP MASS IS 54,000 TONS. SEVENTEEN HUNDRED PASSENGERS ABOARD. MAYDAY MAYDAY MAYDAY.
The other screen lit, giving us what the Register knew about Agamemnon. It didn't look good.
She was an enormous old cargo-passenger ship, over thirty years old—and out here that's old indeed. She'd been built for a useful life of half that, and sold off to Pegasus Lines when P&L decided she wasn't safe. Her auxiliary power was furnished by a plutonium pile.
If something went wrong with it, there was no way to repair it in space. Without auxiliary power, the life-support systems couldn't function. I switched the comm system to Record. ' Agamemnon, this is cargo tug Slingshot. I have your Mayday. Intercept is possible, but I cannot carry sufficient fuel and mass to decelerate your ship. I must vampire your dee and mass, I say again, we must transfer your fuel and reaction mass to my ship.
'We have no facilities for taking your passengers aboard. We will attempt to take your ship in tow and decelerate using your deuterium and reaction mass.
Our engines are modified General Electric Model five-niner ion-fusion. Preparations for coming to your assistance are under way. Suggest your crew begin preparations for fuel transfer.
The Register didn't give anywhere near enough data about Agamemnon. I could see from the recognition pix that she carried her reaction mass in strap-ons alongside the main hull, rather than in detachable pods right forward the way Slinger does. That meant we might have to transfer the whole lot before we could start deceleration. She had been built as a general-purpose ship, so her hull structure forward was beefy enough to take the thrust of a cargo pod—but how much thrust? If we were going to get her down, we'd have to push like hell on her bows, and there was no way to tell if they were strong enough to take it.
The refinery crew had built up fuel pods for Slinger before, so they knew what I needed, but they'd never made one that had to stand up to a full fifth of a gee. A couple of centimeters is hefty acceleration when you boost big cargo, but we'd have to go out at a hundred times that. They launched the big fuel pod with strap-on solids, just enough thrust to get it away from the rock so I could catch it and lock on. We had hours to spare, and I took my time matching velocities. Then Hal and I went outside to make sure everything was connected right. Slingshot is basically a strongly built hollow tube with engines at one end and clamps at the other. The cabins are rings around the outside of the tube.
We also carry some deuterium and reaction mass strapped on to the main hull, but for big jobs there's not nearly enough room there. Instead, we build a special fuel pod that straps onto the bow. The reaction mass can be lowered through the central tube when we're boosting.
Boost cargo goes on forward of the fuel pod. This time we didn't have any going out, but when we caught up to Agamemnon she'd ride there, no different from any other cargo capsule. That was the plan, anyway. Taking another ship in tow isn't precisely common out here. Everything matched up.
Deuterium lines, and the elevator system for handling the mass and getting it into the boiling pots aft; it all fit. Ship's engines are complicated things. First you take deuterium pellets and zap them with a big laser. The dee fuses to helium. Now you've got far too much hot gas at far too high a temperature, so it goes into an MHD system that cools it and turns the energy into electricity.
Some of that powers the lasers to zap more dee. The rest powers the ion drive system. Take a metal, preferably something with a low boiling point like cesium, but since that's rare out here cadmium generally has to do.
Boil it to a vapor. Put the vapor through ionizing screens that you keep charged with power from the fusion system. Squirt the charged vapor through more charged plates to accelerate it, and you've got a drive.
You've also got a charge on your ship, so you need an electron gun to get rid of that. There are only about nine hundred things to go wrong with the system.
Superconductors for the magnetic fields and charge plates: those take cryogenic systems, and those have auxiliary systems to keep them going. Nothing's simple, and nothing's small, so out of Slingshot's sixteen hundred metric tons, well over a thousand tons is engine. Now you know why there aren't any space yachts flitting around out here. Slinger's one of the smallest ships in commission, and she's bloody big. If Jan and I hadn't happened to hit lucky by being the only possible buyers for a couple of wrecks, and hadn't had friends at Barclay's who thought we might make a go of it, we'd never have owned our own ship.
When I tell people about the engines, they don't ask what we do aboard Slinger when we're on long passages, but they're only partly right. You can't do anything to an engine while it's on.
It either works or it doesn't, and all you have to do with it is see it gets fed. It's when the damned things are shut down that the work starts, and that takes so much time that you make sure you've done everything else in the ship when you can't work on the engines.
There's a lot of maintenance, as you might guess when you think that we've got to make everything we need, from air to zweiback. Living in a ship makes you appreciate planets.
Space operations go smooth, or generally they don't go at all. When we were fifty kilometers behind, I cut the engines to minimum power. I didn't dare shut them down entirely.
The fusion power system has no difficulty with restarts, but the ion screens are fouled if they're cooled. Unless they're cleaned or replaced we can lose as much as half our thrust—and we were going to need every dyne. His face didn't change. 'Experienced cadets, eh? Well, we'd best be down to it.
Haply will show you what we've been able to accomplish.' They'd done quite a lot. There was a lot of expensive alloy bar-stock in the cargo, and somehow they'd got a good bit of it forward and used it to brace up the bows of the ship so she could take the thrust.
'Haven't been able to weld it properly, though,' Haply said. He was a young third engineer, not too long from being a cadet himself. 'We don't have enough power to do welding and run the life support too.' Agamemnon's image was a blur on the screen across from my desk.
It looked like a gigantic hydra, or a bullwhip with three short lashes standing out from the handle. The three arms rotated slowly. I pointed to it.
'Still got spin on her.' Ewert-James was grim. 'We've been running the ship with that power. Spin her up with attitude jets and take power off the flywheel motor as she slows down.' I was impressed. Spin is usually given by running a big flywheel with an electric motor.
Since any motor is a generator, Ewert-James's people had found a novel way to get some auxiliary power for life-support systems. Agamemnon didn't look much like Slingshot. We'd closed to a quarter of a klick, and steadily drew ahead of her; when we were past her, we'd turn over and decelerate, dropping behind so that we could do the whole cycle over again. Some features were the same, of course. The engines were not much larger than Slingshot's and looked much the same, a big cylinder covered over with tankage and coils, acceleration outports at the aft end. A smaller tube ran from the engines forward, but you couldn't see all of it because big rounded reaction mass canisters covered part of it. Up forward the arms grew out of another cylinder.
They jutted out at equal angles around the hull, three big arms to contain passenger decks and auxiliary systems. The arms could be folded in between the reaction mass canisters, and would be when we started boosting. All told she was over four hundred meters long, and with the hundred-meter arms thrust out she looked like a monstrous hydra slowly spinning in space.
The fuel transfer was tough. We couldn't just come alongside and winch the stuff over. At first we caught it on the fly: Agamemnon's crew would fling out hundred-ton canisters, then use the attitude jets to boost away from them, not far, but just enough to stand clear. Then I caught them with the bow pod. It wasn't easy. You don't need much closing velocity with a hundred tons before you've got a hell of a lot of energy to worry about. Weightless doesn't mean massless.
We could only transfer about four hundred tons an hour that way. After the first ten-hour stretch I decided it wouldn't work. There were just too many ways for things to go wrong. 'Get rigged for tow,' I told Captain Ewert-James. 'Once we're hooked up I can feed you power, so you don't have to do that crazy stunt with the spin. I'll start boost at about a tenth of a centimeter.
It'll keep the screens hot, and we can winch the fuel pods down.' He was ready to agree. I think watching me try to catch those fuel canisters, knowing that if I made a mistake his ship was headed for Saturn and beyond, was giving him ulcers. First he spun her hard to build up power, then slowed the spin to nothing. The long arms folded alongside, so that Agamemnon took on a trim shape.
Meanwhile I worked around in front of her, turned over and boosted in the direction we were traveling, and turned again. The dopplers worked fine for a change. We hardly felt the jolt as Agamemnon settled nose to nose with us. Her crewmen came out to work the clamps and string lines across to carry power. We were linked, and the rest of the trip was nothing but hard work. We could still transfer no more than four hundred tons an hour, meaning bloody hard work to get the whole twenty-five thousand tons into Slinger's fuel pod, but at least it was all downhill.
Each canister was lowered by winch, then swung into our own fuel-handling system, where Singer's winches took over. Cadmium's heavy: a cube about two meters on a side holds a hundred tons of the stuff.
It wasn't big, and it didn't weigh much in a tenth of a centimeter, but you don't drop the stuff either. Finally it was finished, and we could start maximum boost: a whole ten centimeters, about a hundredth of a gee. That may not sound like much, but think of the mass involved. Slinger's sixteen hundred tons were nothing, but there was Agamemnon too. I worried about the bracing Ewert-James had put in the bows, but nothing happened. Three hundred hours later we were down at Pallasport.
Their first impression was of a bundle of huge cigars. Those were the big fuel tanks almost a hundred meters long. They were so large that they dwarfed the rest of the ship, and ran the entire length of midsection. Behind the 'cigars' was a solid ring that held three rocket motors. Then at the end of a spine as long as the main body of the ship was the nuclear reactor and another rocket motor. This was the real drive. The three chemical rockets were only for steering and close maneuvering.
Wayfarer's power came from her atomic pile. The cigar-shaped tanks held hydrogen, which was pumped back to the reactor where it was heated up and spewed out through the rear nozzle. A ring of heavy shielding just forward of the reactor kept the pile's radiation from getting to the crew compartment.. Despite the large size of the ship, the crew and cargo sections seemed quite small. There were some structures reaching back from the forward ring where the control room was. Two of those were passenger quarters. The other was another nuclear power unit to make electricity to run the environmental control equipment, furnish light for the plants, power to reprocess air, and all the other things the ship and passengers and crew would need.
There was a big telescope and a number of radar antennae on the forward section. The scooter pilot was careful not to get near the reactor in the ship's 'stinger.' The ship had been designed for sixty passengers. She carried twice that number plus eight crew. The internal space was constructed in a series of circular decks.
Each deck had an eight-foot hole in its center, so that from the forward end, just aft of the separately enclosed control cabin, Kevin could look all the way aft to the stern bulkhead. Although there was a long and rather flimsy-appearing steel ladder stretching from aft to forward bulkhead, no one used it. 'F deck,' the crewman said 'A deck is the bridge. B is the wardroom.
C, D, and E are the three aft of that. E happens to be the recreation and environmental control. Yours is the one beyond that.
They're marked.' Finally he reached F deck, which he found to be sectioned into slice-of-pie compartments arranged in a ring around the central well, fifteen of them in all.
He found the one marked '12' and went in. His 'stateroom' was partitioned off with a flexible, bright blue material that Kevin thought was probably nylon. The door was of the same stuff and tied off with strings.
It didn't provide much privacy. Inside the cramped quarters were facilities for two people. There were no bunks, but two blanket rolls strapped against the bulkhead indicated the sleeping arrangements.
It made sense, Kevin thought. You didn't need soft mattresses in space.
'Sleeping on a cloud' was literally true here. You needed straps to keep you from drifting away, but that was all. One viewscreen with control console, a small worktable, and two lockers about the size of large briefcases completed the furnishings. The incident reminded Kevin that he was in free fall, and his stomach didn't like it much. He gulped hard.
'I'll be glad when we're under way,' he said. 'It won't last long, but it will be nice to have some weight again. Even for a day or so.'
Norsedal frowned and rolled his eyes upward for a moment. 'Not that long, I'm afraid,' he said. 'Let's see, total velocity change of about five kilometers a second, at a tenth of gravity acceleration—five thousand seconds.'
He took a pocket computer off his belt and punched numbers. 'An hour and a half. Then we're back in zero-gravity.' Weight felt strange. The ship boosted at about ten percent of Earth's gravity, but Kevin found that quite enough.
All over the ship loose objects fell to the decks. Ninety minutes later the acceleration ended. Wayfarer was now in a long elliptical orbit that would cross the orbit of Ceres. Left to itself, the ship would go on past, more than halfway to Jupiter, before the Sun's gravity would finally turn it back to complete the ellipse and return it to its starting point. In order to land on Ceres, the ship would have to boost again when it got out to the orbit of the asteroid. There would also be minor course-correction maneuvers during the trip, but except for those the ship's nuclear-pile engine wouldn't be started up until they arrived at Ceres's orbit.
Then the ship would accelerate to catch up with the asteroid. That wouldn't happen for nine months. The heart of the system was a series of large transparent tanks filled with green water and tropical fish. Once Wayfarer was under way the crew erected large mirrors outside the hull.
The mirrors collected sunlight and focused it through Plexiglas viewports onto the algae tanks. A ventilation system brought the ship's air into the tanks as a stream of bubbles. Other pumping systems collected sewage and forced it into chemical processors; the output was treated sewage that went to the algae tanks as fertilizer. Wayfarer had two airlocks.
One was right in the bows, a large docking port that allowed smaller space capsules to link up with the ship, and could also be used to link with an airtight corridor connecting the ship with the Ceres spaceport, or even with another ship. The other was a smaller personnel lock on the side of the hull just aft of the bows. Kevin and Ellen went out that way. There was a small ladder leading forward.
It wasn't needed as a ladder, but it provided handholds. The telescope was large, over a foot in diameter, with flexible seals that let it pass through the ship's hull and into the control bridge. The ship's engines started. There was no sound and no flame.
Hydrogen was pumped from the tanks and into the nuclear pile on its sting at the end of the ship. The nuclear reactor heated the hydrogen and forced it back through nozzles. The ship drove forward at a tenth of a gravity.
(ed note: the Medici Explorer is basically the Pilgrim Observer with the NERVA solid core NTR swapped out for a gas-core NTR) The Medici Explorer was fifty-six meters in length, from the gunmetal-grey nozzle of its primary engine to the grove of antennae and telescopes mounted on its barrel-shaped hub module; at the tips of its three arms—which were not yet rotating—the spacecraft was about forty-six meters in diameter. Pale blue moonlight reflected dully from the tube-shaped hydrogen, oxygen, and water tanks clustered in tandem rows between the hub and the broad, round radiation shield at the stern. Extended on a slender boom aft of the shield, behind the three gimbal-mounted maneuvering engines, was the gas-core nuclear engine, held at safe distance from the crew compartments at the forward end of the vessel. Although the reactor stack in Arm Three was much closer to the hub, it was heavily shielded and could not harm the crew when it was in operation. The Medici Explorer was already awake and thriving. Two days earlier, it had departed from Highgate, the lunar-orbit spacedock where it had been docked since the completion of its last voyage six months ago. During the interim, while its crew rested at Descartes City and the precious cargo of Jovian helium-3 was unloaded from the freighters and transported to Earth, the Medici Explorer had undergone the routine repairs necessary before it could make its next trip to Jupiter.
Now, at long last, the giant spacecraft had been towed by tugs to a higher orbit where it was reunited with its convoy. The shuttle made its final approach toward the vessel’s primary docking collar on the hub module. On the opposite side of the docking collar, anchored to a truss which ran through a narrow bay between the outboard tanks, was the Marius, a smaller spacecraft used for landings. The fact that the ship’s boat was docked with the larger vessel was evidence that the Medici Explorer’s crew had returned from shore leave; more proof could be seen from the lights which glowed from the square windows of Arm One and Arm Two. Red and blue navigational beacons arrayed along the superstructure illuminated more details: an open service panel on the hub where a robot was making last-minute repairs; a hardsuited space worker checking for micrometeorite damage to the hull; the round emblem of Consolidated Space Industries, the consortium which owned the vessel, painted on the side of the hub.
Then the shuttle slowly yawed starboard, exposing its airlock hatch to the docking collar, and the Medici Explorer drifted away from its windows. So on and so forth, barely pausing for breath, as we dropped down the hub’s access shaft to the carousel which connects the hub to the ship’s three arms.
Since the arms were not presently rotating, we didn’t need to make the tricky maneuver of reorienting ourselves until the appropriate hatchway swung past us. The carousel’s hatches were aligned with their appropriate arms, so all we had to do was squirm through the upward-bending corridor—passing the sealed tiger-striped hatch which led to the reactor stack in Arm Three—until we reached the open hatch marked Arm 1. The arm’s central shaft resembled a deep well, fifteen meters straight down to the bottom. Although I consciously knew that I couldn’t fall in zero-gee, I instinctively rebelled at the thought of throwing myself into a neck-breaking plummet. While I paused at the edge of the hatch, still visually disoriented by the distance, Young Bill dove headfirst through the hatch, scarcely grabbing the rungs of the ladder which led down the blue-carpeted wall of the shaft.
I shut my eyes for a moment, fighting a surge of nausea, then I eased myself feet-first into the shaft, carefully taking each rung a step at a time. There were six levels in Arm One, each accessed by the long ladder. Still babbling happily about rain forests and South American Indian tribes, Young Bill led me past Level 1-A (the infirmary and life sciences lab) Level 1-B (the Smith-Tate residence), Level 1-C (Smith-Makepeace) and Level 1-D (Smith-Tanaka). The hatches to each deck were shut, but as we glided past Level 1-D, its hatch opened and a preadolescent boy recklessly rushed out into the shaft and almost collided with Young Bill. Young Bill shut the hatch, then led me down one more level to Deck 1-E, the passenger quarters.
He opened the hatch to Deck 1-E and pulled himself inside, hauling my duffel bag behind him. The deck was divided into four passenger staterooms, along with a common bathroom; not surprisingly, it was marked Head, retaining the old nautical term. The small compartment Bill led me to had its own foldaway bed, desk, data terminal and screen, along with a wide square window through which I could see the Moon. Don’t bother making yourself at home,” he said as he stowed my duffel bag in a closet. “After we launch, you won’t see this place again for nine months.” I nodded. “The other passengers they’re already in hibernation?” Yep.
I helped Uncle Yoshi dope ’em up a few hours ago. They’re zombified already. You’ll be joining them after we—” •. The Medici Explorer’s command center was shaped like the inside of a Chinese wok. Located on the top deck of the hub, Deck H-1 was the largest single compartment in the vessel: about fifteen meters in diameter, the bridge had a sloping, dome-shaped ceiling above a shallow, tiered pit. Two observation blisters, each containing an optical telescope, were mounted in the ceiling at opposite ends of the pit; between them were myriad computer flat-screens and holographic displays, positioned above the duty stations arranged around the circumference of the pit. In the center of the bridge, at the bottom of the pit between and slightly below the duty stations, was the captain’s station, a wingback chair surrounded by wraparound consoles.
On one side of the bridge was the hatch leading to the hub’s access tunnel; on the opposite side was a small alcove, a rest area furnished with three chairs and a small galley. It may sound claustrophobic and technocratic, but the bridge was actually quite spacious and comfortable.
The floors were carpeted, allowing one to comfortably walk on them provided that one was wearing stikshoes, and the holoscreens provided a variety of scenes from outboard cameras as well as the main telescope, giving the illusion of cathedral windows looking out upon the grand cosmos. The major technological breakthrough which made Jupiter reachable was made in 2028 by a joint R&D project by Russian and American physicists at the Kurchatov Institute of Atomic Energy and the Lawrence Livermore National Laboratory: the development of a gas-core nuclear engine, resulting in an impulse-per-second engine thrust ratio twice as high as even the thermal-fission engines used by Mars cycleships. He went out in the ship’s service bug, a tiny gumdrop-shaped vehicle with double-jointed RWS arms, used for in-flight repair operations.
Bill had been thoroughly trained and checked out for the bug; indeed, this was the third time he had piloted it during a flight. While Betsy, his dad, and Saul monitored from the bridge, he took the bug out from its socket on the hub, jetted around the ship’s rotating arms, and gently maneuvered the little one-person craft until he reached the maneuvering engines behind the radiation shield.
When creating the Pilgrim Observer, started with a 1960's study on creating a self deploying space station. Stine added the propellant tanks and the NERVA NTR to make it into a spacecraft. You will note the box cover says 'Space Station', not 'Spacecraft'. Identified the space station study in question. Actually studies plural, the Pilgrim was based on an amalgam of several. • (1962) •, Special Section (1963) pages 52-63.
Article by Owen E. Maynard and Rene A. • US Patent #3300162 (1964).
Inventors Owen E. Maynard, Willard M. Taub, David Brown, Edward H. Olling, and Robert M. • MMSS (1965). Study by Lockheed commissioned by NASA Manned Spacecraft Center.
• (1970) • (must be purchased). Article Self-Deploying Space Stations (NAS1-1630) by Dennis R. Pressurized cabin module. Module height is 100 inches (8 feet 4 inches), internal floor to ceiling height is 84 inches (7 feet), floor diameter is 183 inches (15.25 feet), floor interconnect outer diameter 36 inches (3 feet). These are stacked to make the pressurized cabin. In the interim station, crew goes from cabin to cabin via the floor interconnect assembly, and the universal hatches open to space.
In the 3 armed space station intercompartmental access tubes are attached to the universal hatches. Access tubes have a diameter of 60 inches (5 feet). NASA 3-armed station (1962). Green is pressurized cabin.
Yellow is access tube. Blue is floors. Gold is connecting tubes. Light green is annular passageway.
Orange is airlocks. Magenta is rotating pressure seal. Each compartment has its floor curved according to the radius of rotation.
Access tubes flanking cylindrical cabin create oval outline. Note that the access tubes end in airlocks extending outside of the arms.
In each arm, one access tube will have a continuous ladder, the other a conveyer system to transport bulk equipment. Note that supporting the pressurized cabin from two access tubes provides more structural rigidity than the single tube used by the Pilgrim Observer.
US Patent #3300162. Peach color is zero-G lab, it is reverse rotated by a motor to counteract centrifugal gravity. Pale green is equivalent to the 'annular passageway', it is not annular because this design does not have a passageway down the middle for spacecraft to exit. Instead spacecraft exit the same way they entered: through the hatch at the top. Set of #74s are airtight hatches between the yellow access tubes and the pale green central room.
Hatches are surrounded by the rotating seals, station arms pivot around this point. Note quad jet at bottom of green pressurized cabin, very similar to jet on bottom of reactor stack in Pilgrim plastic model. Mass Schedule Item Mass (kg) Prop/Power engines (3) 22,380.0 Heat radiator (rear) 1,200.0 Computers (4) 80.0 Navigation equipment 75.0 Power Bus 30.0 RCS rear 13,251.9 Common tanks (2 in rear) 167,154.7 Fuel tank cluster (7) 585,041.3 Power Bus B 200.0 Phobos scientific equip. 150.0 Navigation 75.0 Truss 7,000.0 Landing legs 495.0 Travel Pod 5,500.0 Portable antenna equip. 650.0 Heat radiator (front) 880.0 Comm. Boom 1,000.0 2 Antennas 200.0 2 Tranceivers 400.0 4 Star Trackers 20.0 Telescopes & Pointing Sys.
600.0 Solar flare detection 100.0 Power Bus C 300.0 Planar truss 6,000.0 RCS (front) 13,251.8 Ext. Thermal transport 700.0 LOX/H2 tanks 723.6 LOX/N2 tanks 2638.0 Hab modules 69,034.0 TOTAL 899,130.0 Yes, I know elsewhere in the report it states the ship mass is 893,000 kg.
The report has, shall we say, some inconsistencies. The spacecraft is a truss composed of cubic modules that are collapsible and self deploying. Each module is 8.3 x 8.3 meters, with each edge strut only 0.16 meters in diameter. They are composed of graphite-epoxy composite. The main truss is a stack of 11 modules while each communication truss arm is a stack of 3 modules. They are rated for up to 0.56 g in compression, with a 1.4 factor of safety. The truss modules are collapsible because heavy lift vehicles have limited payload volume.
The truss modules are self deploying because orbital assembly is enough of a nightmare without requiring the poor astronauts to assemble edge struts like a zero-gee from hell. The twin habitat modules are modified International Space Station modules. Each module is encased in a layer of multi-layer thermal insulation, followed by an outer layer of anti-meteor aluminum.
Stringers running the length of each module control bending, and bulkheads encircling the cross section control radial expansion. It is designed to withstand an internal pressure of 11 psi. Each module is 4.7 meters tall by 16.9 m long by 4.2 meters wide.
Each of the two modules has one airlock, located on the opposite end from its twin. The life support system is partially-closed. It has a 90% efficiency recycling breathing mix and a 95% efficiency recycling water. 1,000 kg of oxygen and 5,550 kg of water are carried as consumbables for the mission (includs a 15% contingency). In addition 4,720 kg of dried food is carried. Was chosen for fire extinguishers because 'it leaves no corrosive or abrasive residues within the cabin and few ill effects for humans.' Wikipedia states that.
But it does say it is better for use inside a spacecraft because it produces less toxic by-products than does. The spacecraft uses spin gravity. Spin axis is the spacecraft 'z-axis', parallel to the long axis of the twin habitat modules. The target value for the spin gravity is 0.5 g. Maximum allowable spin rate is. The spin rate will vary between 2.67 to 3.06 rpm, depending upon the location of the center of gravity at specific points in the mission. The CG will shift location as propellant is consumed.
So the radius of rotation (distance from CG to crew modules) will vary from 63.75 meters (full propellant tanks) to 47.75 meters (). The spin gravity will have to be despun for course corrections and for emergency procedures. There is enough RCS fuel to support eight spin/despin pairs (9,360 kg fuel). Four for course corrections en route to Phobos, two for course corrections en route to Terra, and two for emergencies. Emergencies include EVA to repair ship systems and mission abort scenarios.
Spinning up or despinning down takes about five minutes and 585.1 kg of RCS fuel. Radiation exposure is assumed to come from four sources: • Solar flares (solar proton storms) • Galactic cosmic radation (GCR) • Solar wind • Spacecraft nuclear engines Maximum total for each crew member was set at 0.65 Sievert per year, and 0.33 Sievert per month. Total for the entire mission was estimated to be 0.95 Sievert. Radiation protection from the nuclear engines is provided by standard composed of tungsten and lithium hydride, and by a minimum of 40 meters.
The shadow is set such that both the propellant tanks and the communication platfors are within the shadow. Protection from solar flares is provided by a around the sleeping quarters. The cellar has ceiling and walls containing lithium hydride, the floor has a water tank. No protection is provided from solar wind and GCR, the crew knew the job was dangerous when they took it.
The spacecraft has two 9-meter antenna mounted on the communication truss. These transmit on the Ka-band to geosynchronous relay satellites around Terra. These provide 50 megabit per second full duplex connections to Mission Control on Terra. This allows continuous transmission of voice and video communication, experimental data and obsevations, and telementry.
The communication truss is parallel to the tumbling pigeon spin axis. This allows the antennae to be easily de-spun by simply rotating in the opposite direction, so they stay on target. Guidance, Navigation, and Control (GN&C) of the spacecraft is achieved by the computer-managed interaction of the navigation, telemetry, and propulsion systems. The computer system consists of nine radiation-hardened, spaceready General Purpose Computers (GPC), each providing 16 MIPS of computing power.
All computers will be linked in a FDDI-2 network. The navigation system consists of four star trackers to determine the spacecraft's attitude and position, an Optical Alignment System to recalibrate the star trackers, nine Inertial Measurement Units to sense linear rates of acceleration, and nine Ring Laser Gyroscopes to measure angular rates of acceleration.
This system will also monitor the spinning motion of the spacecraft. The telemetry system consists of a long range, high gain radar and a short range landing radar. These radars will guide the spacecraft into the proper Phobos rendezvous position. The nuclear engines are Rocketdyne NERVA derivatives using carbide reactors.
Nuclear engines were chosen to reduce overall trip time, thus increasing reliability and efficiency. And also reducing crew radiation dose. Each reactor can operate up to 12 hours at full propulsion, and has a lifetime of three years. Three engines are used to escape LEO, only two engines are needed for the rest of the mission. A reactor core can be brought to full power within 60 seconds. After each main burn, propellant is wasted for up to six hours afterwards to cool the blasted reactor core down.
The three engines are stacked vertically (along the Y axis). This increases stability during spin. The middle engine will be jettisoned when it is no longer needed and the mission completed with the remaining two. There are three unrefrigerated propellant tanks dropped after escape from LEO. Four tanks are dropped in Mars orbit. There are two permanent tanks used for the trip home to Terra. Nine tanks total.
Which confuses me since the blueprint appear to show only 8 tanks. For normal operations the spacecraft requires 175 kW e of electrical power (life support, communication, experiments, cryogenic cooling of propellant tanks). It will need to supply this power for the entire two-year mission.
Solar panels were rejected in favor of rigging the engines to be (they call it Dual-Mode). The spacecraft only needs one engine rigged as bimodal to provice 175 kW, but the design rigs all three so there are two backups. All three share a common heat radiator, because radiators are heavy suckers that really cut into your payload budget. The designers wanted to use low-mass or radiators with the bimodal generators, but they proved to be incompatible with tumbling pigeon spin gravity. So they went with standard weighty. The life support uses heat-pipes with an internal two-phase water loop to transport the heat and an external two-phase ammonia loop to reject the heat. The engine in bimodal power mode uses heat-pipes with a helium-xenon mixture.
The engine in thrust mode uses open cycle cooling (the exhaust is the heat radiator) so it don't need no stinkin' heat pipe. The problem with bimodal is that while an engine is providing thrust, you cannot also use it to generate electricity. It would burn up the power generating heat radiator (a given radiator design can only handle heat in a narrow range). So the design needed an auxiliary power supply for use for the duration of the burn. They figured the maximum burn duration was six hours. So they equipped the spacecraft with a. Those usually are paired with solar cells, but in this case it is paired with the bimodal reactor.
The fuel cell has enough fuel to provide a bare 20 kW e for 24 hours (enough for basic life support, communication, and computers). Then when the burn is over bimodal power can be used to regenerate the fuel-cell fuel. The total mission time is 656 days, using an opposition class mission. 318 to travel from Terra LEO to Phobos (including a Venus flyby to conserve fuel). 60 days are spent at Phobos setting up the processing plant and performing experiments. Finally 278 days are spent traveling back to Terra. The intial perigee kick to place the spacecraft on trans-Mars insertion will regrettably send it through the Van Allen radiation belts, but the dose should be only 0.06 Sieverts.
The total dose for the first 30 days is estimated to be 0.28 SV, which is below the 0.33 SV monthly limit. The spacecraft will enter a 9,400 km Mars orbit, about 22 kilometer higher than Phobos. This is only barely within Mars' gravity well, which greatly lowers the required delta-V. Future missions with Mars landings can also get by with a greatly lowered required delta-V, since they can refuel at Phobos instead of having to lug the landing propellant all the way from Terra. After careful calculation the spacecraft will perform a phasing burn to put it 6 kilometers over Stickney Crater on Phobos.
No closer because of the danger of the RCS control jets blowing foreign objects off the surface into the ship's hull. Due to the low gravity of Phobos (1/1000th g or 1 cm/sec 2) the ship will not land so much as it will 'dock.'
When it comes within twenty meters of Phobos it will shoot harpoons and reel itself down to the surface. These are needed since the landing site does not have the same velocity as the center of mass of Phobos. The spacecraft will remain tethered until departure because Phobos' anemic gravity is too weak to prevent the ship from drifting away.
After 60 days of science the ship will cast off the harpoon cables and push away from Phobos using the reaction control system. The main engines will then put the ship into Terra trajectory.
Upon arrival it will burn to enter a high elliptical orbit. The crew will be removed by an orbital transfer vehicle. The crew-less ship will then do a slow transfer to LEO under autopilot. The ship can the be refurbished for a new mission. Mission Δ V Burn Δ V Description Δ V 1 4,500 m/s Terra orbit to transfer ellipse 1 Δ V 2 4,170 m/s Transfer ellipse 2 to Mars orbit Δ V 3 2,950 m/s Mars orbit to transfer ellipse 3 Δ V 4 2,820 m/s Transfer ellipse 3 to Terra orbit Δ V m 668 m/s Course correction, Phobos land/launch Gravity loss 125 m/s Δ V Total 15,233 m/s PROCESSING FACILITY The processing facility extracts water from Phobos regolith and turns it into cryogenic liquid oxygen and liquid hydrogen. This will transform Phobos into a transportation node for the inner solar system. This will allow such things as economically reaching the asteroid belt with a chemically fueled rocket.
Phobos is estimated to have 330 cubic kilometers of water ice (assuming it is a Type 1 carbonaceous chondrite body). Depending on one's assumptions, 4 cubic kilometers of ice could support fuel requirements for the next fifty years of space exploration. Phobos also has resources such as aluminum, magnesium, silicon, iron, and nickel. This can be used as raw materials for factories producing material fibers, glass, silicon chips, ceramics, magnets and space truss elements. The processing facility is assumed to have been delivered into Phobos orbit by a prior unmanned mision, and will be set up by the crew of the Wolverine. It is also assumed that Phobos' Stickney Crater is solid rock covered by up to 200 meters of regolith.
It is composed of five main parts: • Power • Excavation of Regolith • Transportation of Regolith to Facility • Processing of Regolith • Storage of Resources The plant will be set up near one of the walls that make up Stickney crater. This will allow for maximum radiation shielding for the plant given by the natural surroundings.
Power requirements were estimated to be about 1 megawatt: 400 kW for oven to bring regolith up to 700°C, 200 kW for electrolysis, and 400 kW for blowers, magnetic separator, crusher, etc. This will be supplied by a pair of with an output of 550 kW each. The two reactors will be installed using a LEVPU. The LEVPU is a modified version of a Lunar core sampler used in the Apollo 15 and 17 missions.
The LEVPU digs a cylindrical hole and places a casing around it to prevent the hole from caving in. The nuclear reactor is then robotically placed in the casing. The Regolith acts as radiation shielding for the reactors. This allows human operations to occur within 300 m of the reactors. For the inside details about the Orion propulsion system go. Please note that Orion drive is pretty close to being a, and is not subject to the rule.
It is probably the only torchship we have the technology to actually build today. If you want the real inside details of the original Orion design, run, do not walk, and get a copies the following issues of of Aerospace Projects Review:,, and. They have blueprints, tables, and lots of never before seen details.
If you want your data raw, piled high and dry, of report GA-5009 vol III 'Nuclear Pulse Space Vehicle Study - Conceptual Vehicle Design' by General Atomics (1964). Lots of charts, lots of graphs, some very useful diagrams, almost worth skimming through it just to admire the diagrams. The following table is from a 1959 report on Orion, and is probably a bit optimistic. But it makes for interesting reading. Note that 4,000 tons is pretty huge. The 10-meter Orion (the one in all the 'Orion' illustrations) is only about 500 tons. In other words, if you can believe their figures, the advanced Orion could carry a payload of 1,300 tons ( NOT kilograms) to Enceladus and back!
Interplanetary Ship Advanced Interplanetary Ship Gross Mass 4,000 tons 10,000 tons Propulsion System Mass 1,700 tons 3,250 tons Specific Impulse 4000 sec 12,000 sec Exhaust Velocity 39,000 m/s 120,000 m/s Diameter 41 m 56 m Height 61 m 85 m Average acceleration up to 2g up to 4g Thrust 8×10 7 N 4×10 8 N Propellant Mass Flow 2000 kg/s 3000 kg/s Atm. Image from and colorized by me.
Note ghost images of the pusher plate position and shape when fully compress and when fully extended. • Artwork by Master Artist. Click for larger image Most of the information and images in this section are from.
I am only giving you a 'Cliff Notes' executive summary of the information, and only a few of the images and those in low resolution. If you want the real deal, get a copy of APR v1n5. Orion drive spacecraft scale up quite easily.
However, unlike other propulsion systems, they do not scale down gracefully. Surprisingly it is much more of an engineering challenge to make a small Orion. It is difficult to make a nuclear explosive below a certain yield in kilotons, and small nuclear explosives waste most of their uranium or plutonium. But it is relatively easy to make them as huge as you want, just pile on the megatons.So in the 1960's when General Atomic made their first pass at a design, it was for a. Alas for General Atomic, neither the United States Air Force (USAF) nor NASA wanted it. USAF had no need for a ship sized for being a space going battleship (they but President Kennedy smacked them down).
NASA wanted nothing to do with a spacecraft that would make the Saturn V and its infrastructure obsolete and pitifully inadequate overnight. So General Atomic heaved a big sigh, and started designing a tiny Orion drive craft with only a 10 meter diameter pusher plate.
However, reveal that the USAF's decision to cancel plans for the 4000 ton Orion was a near thing. If some of the high-ranking USAF officers had slightly different personalties, today there would be a US Space Force with Orion spacecraft sending expeditions to Enceladus. Since General Atomic was trying to sell the design to a couple of organizations with vastly different missions in mind, GA made the design modular. There was a basic propulsion system that one could attach any number of different payloads, and customizing the amount of propellant was as easy as stacking poker chips. In this section we will be focusing on the USAF design.
After the USAF lost interest, General Atomic started working with NASA to customize the Orion to their needs. This made the NASA design quite different from the USAF design.
NASA was losing intererest even before the of 1963 killed the Orion dead. USAF 10M ORION ΔV 31,800 m/s Exhaust Velocity 32,900 m/s Propulsion Module 107,900 kg Propellant (Full Magazine Stack) 294,260 kg Payload Stack (Operational Mass) 73,075 kg Wet Mass 475,235 kg Dry Mass 180,975 Mass Ratio 2.63 The USAF 10M Orion had three main components: the Orion Drive propulsion module, the stacks of magazines containing the nuclear pulse units (the Propellant), and the Payload Stack. The Propulsion Module containes the cannon firing the nuclear pulse charges.
It also has the massive array of shock absorbers allowing the spacecraft to absorb the nuclear explosion without being crushed like a bug. It also contains 138 'starter' nuclear pulse units. These are half strength units used to initiate a period of acceleration. The Magazine Stack holds the (full-strength) nuclear pulse units.
Each magazine holds 60 units. There are six magazines in a layer, holding 360 units. This design can hold up to ten layers depending upon how much delta V it needs, but if it has an odd number of magazines they must be balanced around the thrust axis. A full load of ten layers contains 3,600 pulse units. The Payload stack has three components: Powered Flight Station, Personnel Accommodations, and the Basic 12-Meter Spine. The Spine rests on the propulsion module and has the magazine stack frame attached.
The spine contains the spare parts, the repair shack, and mission specific payload. Some of the mission payload is attached outside the spine, such as the Mars Lander.
On top of the spine is the Personnel Accomodations. This holds the life support, the crew quarters, laboratories, and workshops. On top of the Accomodations is the Powered Flight Station. This contains the anti-radiation storm cellar, which contains the flight controls used when the ship is accelerating (since exploding nuclear bombs make radiation). In an emergency, the entire section can turn into a large escape life-boat rocket and fly away from the rest of the spacecraft.
The life-boat has about 600 m/s of delta V and enough life support to keep the 8 person crew alive for 90 days. Note that in the table the mission specific payload is not included. The more of that which is added, the lower becomes the delta V. Nuclear Pulse Unit Container and electronic mass 6.9 kg Nuclear device mass 72.1 kg Total mass 79 kg Diameter 0.36 m Height 0.6 m Yield 1 kt Propellant per pulse 34.3 kg Thrust per pulse 2.0×10 6 N Specific Impulse 3,350 seconds Exhaust velocity 32,900 m/s Detonation interval 0.8 to 1.5 sec 0.86 sec is std The USAF are atom bombs. They were about 0.6 meters tall, had a mass of 79 kilograms, produced a 1 kiloton nuclear explosion, and produced 2.0×10 6 Newtons of force per pulse unit. They were basically nuclear shaped charges.
80% of the blast was focused on the pusher plate instead of being wastefully sprayed everywhere. The latter NASA pulse units had more mass, more Newtons of force, but a lower specific impulse. The propulsion system also carries 138 'starter' nuclear pulse units. These are half-strength (1.0×10 6), used to start a period of acceleration. A starter pulse is used on a stationary pusher plate, a full strength pulse is used on a pusher plate in motion.
The first shot will be a starter pulse, and the remaining pulses will be full-strength for the rest of the acceleration period. You see, a half-strength push is enough to push the plate from the neutral position up to the fully compressed position. A full-strength push is enough to stop a plate moving downward and start it moving upward. Using a full-strength push on a stationary plate will give it twice as much as it need, driving the pusher hard into the body of the spacecraft and gutting it like a trout.
And using a half-strength push on a plate in motion will just halt the plate but provide no useful acceleration. Naturally if one of the full-strength units misfires, the pilot will wait for the pusher plate to settle down then start anew with a fresh half-strength unit. The layer of tungsten propellant should be as thin as possible. However, there are limits to how wide it can be (or a pulse unit will have an inconveniently large diametr) and it should be thick enough to stop most of the neutron and gamma radiation (to reduce the radiation exposure on the ship in general and the on the propulsion module in particular). The mass ratio of the tungsten propellant to the beryllium oxide channel filler should be about 4:1. Each unit had two copper bands, that are bitten into by the rifling of the cannon that shoots these little darlings. The rifling spins the pulse units like rifle bullets, for gyro-stabilization.
Magazine Stack Empty magazine 181 kg Single pulse unit 79 kg Pulse units in magazine 60 Total pulse unit 4740 kg Loaded magazine 4,921 kg 1 stack layer (6 magazines) 29,526 kg Pulse units in 1 stack layer 360 Full stack (10 stack layers) 294,260 kg Pulse units in full stack 3,600 Pulse units were packaged in disk shaped magazines, 60 nukes per magazines. The magazines were stacked like poker chips on top of the propulsion module, held in a hexagonal truss. There are six stacks, with a maximum height of 10 magazines. The bottom six magazines attach directly to the propulsion module's feed system. The open end of a magazine fits onto one of the propulsion module's six 'pulse system conveyors'.
On the magazine, a slot in the side called a 'sprocket opening' allowed one of the propulsion system's sprockets to be inserted into the magazine. As it spins, the star-shaped sprocket grabs the next pulse unit and feeds it into the pulse system conveyor. From there the pulse system travels deep inside the propulsion module to the launch position. Pulse units are drawn simultaneously from the bottom six magazines.
'Bottom' because that is the layer which attaches to the propulsion system's pulse system conveyor. 'Simultaneously' because you do not want the spacecraft's center of gravity straying from the thrust axis. Those pulse units are heavy, and they do not automatically redistribute the mass like fluid propellant in a tank. When the bottom six magazines are empty (360 pulse units expended), propulsion is momentarily halted, and the six 'ejection actuators' (pistons) push on the ejection pad of their respective empty magazine and catapult the empty into space. Sort of like flicking a bottle-cap off the bar room table with your finger. The 'stack drive pinions' then engage the racks on the magazine stack and lower the entire stack down until it engages the propulsion system's pulse system conveyor.
Propulsion is restarted. Propulsion Module Pusher plate mass 47,800 kg Shock absorber and launcher mass 42,900 kg Engine mass pusher+shocks+ launcher 90,700 kg Structural mass 17,200 kg Total module mass 107,900 kg Module diameter 10 m Module height Mode IB 26 m Propellant per pulse 34.3 kg Thrust per pulse 2.0×10 6 N Specific Impulse 3,350 seconds Exhaust velocity 32,900 m/s Detonation interval 0.8 to 1.5 sec 0.86 sec is std The propulsion module is build around a compressed gas cannon that fires nuclear pulse units downward through a hole in the pusher plate. Once the pulse unit reaches a point 25 meters below the pusher plate, the it detonates. The shaped charge channels the explosion into a 22.5° cone perfectly covering the pusher plate. Since premature detonation of a pulse unit would probably utterly destroy the entire spacecraft, there are incredibly stringent controls on them.
The units are locked into safe mode and as such are as impossible to detonate as the designers can possibly make them. Otherwise no astronaut is going to set foot inside a spacecraft carrying enough nuclear warheads to totally vaporize the entire thing. 3.6 megatons is nothing to sniff. If everything is nominal, the arming signal is transmitted to a launched unit when it approaches the 25 meter detonation point. If the engine control computer determines that the synchronization between the pusher, the shock-absorber system, and the pulse unit are within tolerances; the detonation signal is sent when the unit arrives at the detonation point. If anything is wrong, the computer instead transmits the 'safety' signal and the unit enter safe mode again. When the pulse unit is a safe distance away, the computer sends a destruct signal.
You don't want unattended nuclear explosives just flying through space. If the computer sends the standard detonation signal but the pulse unit fails to do so, it is automatically disarmed (we hope). Again the destruct signal is sent once the unit is safely away, hopefully the unit will oblige.
But since the unit has already failed to detonation on command once already, something is obviously wrong with it. Whether it will actually disarm then destruct is anybody's guess. It goes without saying that the various pulse unit radio signals will be heavily encryped to prevent sabotage.
Especially if the spacecraft in question is a military vessel. Otherwise an enemy ship could send the detionation code to every single pulse unit on board, and cackle as your ship did its impression of a supernova. Because the pusher plate has a hole in the center, part of the blast will sneak through and torch the business end of the cannon. The cannon has a plasma deflector cone (with 1.27 centimeters of armor) on the end to protect it. When a pulse unit emerges from the cannon, the deflector cone opens for a split second to let it out. The deflector cone has its own tiny shock absorbers, of course.
The rest of the conical base of the propulsion module is also armored, since the deflector cone will be deflecting plasma all over the base. When the blast hits the pusher plate it gives thrust to the spacecraft, like a nuclear powered boot kicking you in the butt at 32 kilometers per second. Alfa Network Wireless Usb Adapter Model Awus036h Driver Download there.
To prevent this thrust from flattening the ship like a used beer can, two stages of shock absorbers do their best to smooth out the slam. The first stage is a stack of inflated flexible tubes on top of the pusher plate.
It takes the 50,000 g of acceleration and reduces the peak acceleration to a level that can be handled by a rigid structure. Such as the rigid second stage shock absorbers. The second stage is a forest of linear shock absorbers. They reduce the peak acceleration further to only a few gs. The structural frame is welded out of T-1 steel I-beams to take the jolt and transfer the thrust from the shock absorbers to the payload. A set of six torus tanks pressurizes the linear shock absorbers and lubricates their interiors with large amounts of grease.
You need that grease, those linear shock absorbers are working real hard. If one seizes up the results will be. In between blasts the inflatable first stage shock absorbers oscillates through 4.5 cycles (no doubt making a silent sad cartoon accordion noise), while the second stage absorbers go through one half cycle.
The first stage oscillates between being 0.6 normal height to 1.4 height. As each pulse unit is fired, a fine spray of ablative silicone oil coats the pusher plate to help it survive the blast. With the oil coating, each nuclear charge raises the temperature of the plate by only 0.07° Celsius.
Typically acceleration periods use only 1,000 pulse units at a time, which would raise the pusher plate temperature by only 70° C. The effective thrust is the thrust-per-pulse divided by the detonation interval.
So 2.0×10 6 / 0.8 = 2.5×10 6 N effective thrust. This means a series of nuclear bombs going off every 4/5ths of a second. Boom Boom Boom Boom Boom! The compressed gas cannon uses ammonia (NH 3), stored in the 'gas collector and mixing tank'. This is the top-most of the torus (donut) shaped tanks around the core. The tank holds about 8 metric tons of ammonia, and 2 kilograms are used for each shot.
Which means the tank is good for about 4,000 shots. A full set of magazine stacks + the start and restart pulse system has 3,600 + 138 = 3,738 total pulse units so this should be ample. If more ammonia is needed, there is room to spare inside the propulsion system.
Alternatively extra ammonia tanks could be stored inside the Basic Spine. The cannon barrel is 12 meters long, aimed straight down. The cannon accelerates the pulse unit at 45 g giving them a velocity of 90 meters per second. The barrel is rifled to spin the pulse unit at 5 rps. When the nuclear charge reaches the 8 meter point inside the barrel, exhaust manifolds frantically try to suck out all the ammonia gas and spit it out the ejector gas exhaust tubes. The idea was to have no ammonia between the pusher plate and the detonating nuclear charge.
The shaped charge blast could accelerate the ammonia and damage the pusher plate. The main source of nuclear pulse units is from the magazines stacked on top of the propulsion module. However, the module carries 138 pulse units internally in its 'start and restart pulse system.'
They are stored at the top of the module in six curving channels holding 23 pulse units apiece. These are special half-strength pulse units (0.5 kt, 1×10 6N). They are used as the first shot for engine start or in the event of a regular pulse unit misfire. A half-strength unit is used on a stationary pusher plate, a full strength unit is used on a pusher plate in motion. When I was playing around with my, I did discover something unexpected.
The blasted thing needs lots of RCS attitude jets, it turns with all the speed of a pregnant hippo. As near as I can figure part of the problem is [A] the propulsion system is very lightweight since it is mostly hollow shells and inflated tubes (see below) and [B] the magazine canisters are very dense since they are jammed full of pulse units composed of uranium and beryllium oxide. Cannon is gas collector & mixing tank + gas measuring tank & admission valve + ejector tube + ejector gas exhaust + plasma deflector cone (red).
Regular pulse system conveyor at top right attaches to a magazine (blue) The start & restart system storage conveyor is at the top left, internal (blue) The first-stage shock absorbers are at the bottom on top of the pusher plate (green) The second-stage shock absorbers are the columns rising from the pusher plate (green). They are pressurized and lubricated by the six coolant & anti-ablation oil tanks •. Focus is on the gas cannon and the two pulse system storage and conveyors. Start & restart pulse storage is at upper left, contains half-charges for beginning an acceleration period. Magazine and pulse system conveyor is at upper right, with magazine resting on top of propulsion module. Ammonia gas from gas collector & mixing tank travels up tube to gas measuring tank at breech of gas cannon. The gas admission valve fires the cannon, allowing the ammonia to propel the pulse unit down the ejector tube.
At 8 meters down, the ammonia is removed by the ejector gas exhaust so it does not vent out of the end of the cannon. The plasma deflection cone opens for 0.2 seconds to allow the pulse unit to exit the muzzle of the cannon. Mode I operation (chemical booster lofts Orion to 90 km, Orion then uses high acceleration to climb into LEO).
Shown are acceleration 1.0g, 0.8g, and 0.6g Mode II operation (chemical booster lofts empty Orion with minimum pulse units to 90 km, Orion then uses high acceleration to climb into LEO, chemical boosters loft supplies and full load of pulse units to orbiting Orion). Unlikely to be used since has disadvantages of both Mode I and Mode III and none of the advantages.
Mode III operation (gargantuan chemical booster lofts fully loaded Orion into LEO). Before a propulsion manuever, pusher plate starts in 'Neutral' position  A half-strength 'starter' pulse unit is fired to the 25 meter detonation point. Its pulse has just enough impulse to kick the pusher plate up to the 'Compressed' position  The shock absorbers recoil the plate down to the 'Extended' position. While this is happening, a full-strength pulse unit is fired to the 25 meter detonation point  When the pusher plate is all the way down at the 'Extended' position the full-strength pulse unit detonates. It has enough impulse to kick the pusher plate up to the 'Neutral' postion and more impulse to kick it up to the 'Compressed' position The sequence repeats starting at  until the maneuver is finished Note how first-stage shock absorbers dramatically expand and contract. Mission Payload Stack Structural Mass Powered flight station (8 crew) 1,730 kg Personnel Accommodations (8 crew) 7,600 kg Basic 12-m spine 2,270 kg Total structural mass 11,600 kg Operational Payload Mass (including structural) Powered flight station (8 crew) 29,955kg Personnel Accommodations (8 crew) 36,950 kg Basic 12-m spine 6,170 kg Total Operational Payload Mass 73,075 kg Mission Specific Payload Mass Terra ⇒ Mars 750 kg to 150,000 kg Since General Atomic was trying to market the 10 meter Orion to both the USAF and NASA, they made it modular instead of integrated.
That way they could have a common propulsion system for both, with customized payload stacks for each. The example payload stack shown here is for a Mars mission. A chemical rocket using a Hohmann trajectory would take at least nine months to travel to Mars. But the Orion drive rocket could go to Mars and back in four months flat! However the mission that General Atomic finally settled on was a more pedestrian fifteen month mission requiring only 22.2 km/s of delta V. This would only need a mass ratio of 1.93.
If my slide rule is not lying to me, this means it needs about 2149 pulse units (36 magazines or 6 layer magazine stack). All the payload stacks started with a Basic 12-Meter Spine at the bottom, resting on the top of the propulsion module with the magazine supports tied to it. In the Mars mission, this contained the space parts and the repair shack. On top of the Basic Spine was the Personnel Accommodations. This contains the life support system, crew living quarters, and laboratories. At the very top is the Powered Flight Station.
This contains the anti-radiation storm cellar. The crew shelters inside in case of space radiation storms. The crew also shelters inside while the Orion drive is operating, since a series of nuclear detonations is also very radioactive. This is why the flight deck is located inside. Finally the entire level can detach and turn into an emergency life boat if something catastrophic happens to the main ship.
Usually you have a 10-meter propulsion module topped with a Basic 12-m Spine, topped with an 8-crew Personnel Accomodation, topped with an 8-crew Powered Flight Station. However it is possible to replace the last two items with a 20-crew Personnel Accomodation topped with a 20-crew Powered Flight Station. The 20-crew Accomodation needs its base modified to attach to the Basic Spine, it was originally designed to attach to the larger diameter spine of a 20-meter propulsion module. 20-person Payload Stack (note presence of 'Mission Management Centre').
Artwork by Since the spacecraft is long and skinny, it uses the ' method of artificial gravity. This is where the spacecraft rotates end over end, at four revolutions per minute. For a 50 meter long spacecraft this would give about 0.45 g at the tip of the nose, gradually diminishing to zero at the point where the basic spine joins the propulsion module. The amount of gravity will change as pulse units are expended, thus shifting the center of gravity, rotation point, and rotation radius. This does pose a problem in the internal arrangement. While under acceleration the direction of 'down' is towards the pusher plate. But while tumbling, the direction of 'down' is where the nose of the ship is pointing.
So if you are standing on the 'floor' during acceleration, when it switches over to tumbling you will find yourself falling 'upwards' and end up standing on the ceiling. As it turns out, if the ship is accelerating it also means that everybody is huddling inside the storm cellar (or dying of radiation poisoning). Therefore the storm cellar is built with 'pusher-plate is down' orientation, and the rest of the ship is build with 'nose is down' orientation. This also means that the entire mission payload stack has to have a structure that can handle tension as well as compression. Basic 12-Meter Spine Operational Payload Mass Structural Mass 7,600 kg Spares 1,130 kg Repair Equipment 2,270 kg Checkout instrumentation 500 kg Total Operational Payload Mass 6,170 kg Dimensions Diameter 3.2 m Height 12 m The spine has an internal volume of about 97 cubic meters. It contains spare parts, a repair bay, and miscellaneous payload. There is also an airlock on the bottom allowing repair crews to enter the propulsion module.
It is constructed out of materials with a low potential. In addition, each pulse unit is only about 1kt (not a lot of neutrons), they are detonated 25 meters away from the propulsion unit (), and the pulse unit channel filler plus tungsten propellant will provide shielding. It will be radiologically safe for crews to enter the propulsion module a couple of hours after the the most recent nuclear detonation. Orion Mars Mission Propulsion Module Specific Impulse (Exhaust Vel) 2,500 s (24,500 m/s) Thrust 3,500,000 N Dry Mass 91,000 kg Pusher Plate Diameter 10 m Height 21 m This is from by Paul R. Basically it shows how an Orion-powered Mars mission is so superior to a chemically powered mission that it just isn't funny. The family of Mars missions uses the basic, since that can be lofted by a Saturn V.
If you limit mission designs to non- missions, it still has outrageous amounts of delta-V. The study found it could handle mission with delta-V ranging from 12,000 to 34,800 m/s and payloads from 45,000 to 200,000 kilograms. The Orion can do the same miniscule mission as a chemically powered rocket if the Orion has a total Initial Mass In Low Earth Orbit (IMLEO) of only 290,000 kg.
But that's where the chemical rocket maxes out while the Orion is just getting started. You can load it with metric tons of extra propellant and do the mission in 200 days flat instead of three years. Or you can increase the mission to 400 days, but add lots more scientist to the crew along with tons of scientific instruments. You can even add more fuel and return to an elliptical orbit around Terra using a brute-force rocket thrust braking instead of barbecuing the ship with.
Orion has power to spare and then some. The standard Mars missions designed use multiple Saturn V launches to loft the components into orbit. But if you want to cut costs and have the political will, you can boost the Orion spacecraft into orbit with one Saturn V launch — if you don't mind it switching to Orion nuclear pulse drive while still in the atmosphere, starting at an altitude of 50 nautical miles (93 km). But just try explaining that to your hysterical constituents.
• click for larger image Nucler Pulse Propulsion Module Internal details of the engine can be found. It has a specific impulse of 2,500 s (exhaust velocity of 24,500 m/s), a dry mass of 91,000 kg, and an effective thrust of 3,500,000 N. 'Effective' because the thrust is not continuous, the nukes go off at about 1 second intervals.
The interesting thing is all the various Mars missions can be performed by the basic Orion propulsion module as is. All you have to do is change the number of it carres. The raw might of nuclear fission makes this engine very flexible. The propulsion module does have limited internal space for internal magazines, but the bulk of the nuclear pulse units are a carried in, which are ejected when empty. Propulsion module (hot pink in diagram) does not include payload spine (green) nor the (empty) external propellant magazines with magazine support structure (gold). In other words the 91,000 kg dry mass is just the hot pink part.
Especially since the number (and mass) of magazines varies with the mission. The study authors wanted to avoid a lot of tedious calculation so they used a simplification. To do calculations for all the missions, the correct way is to total up the the mass of the needed empty magazines, the RCS propellant, and whatnot to be added to the 'dry mass' for.
This takes forever. The study authors found out that you get much the same answer if you simply downgrade the propulsion module's specific impulse by a fixed percentage. For this module (with some internal magazine storage capacity), a 4% downgrade of specific impulse would account for magazine weight, magazine support structure, and the (RCS) fuel. But with lots less math. For the above reason, instead of as if the propulsion module had a specific impulse of 2,500 seconds, they instead used 2,500 / 1.04 = 2,405 seconds (and an exhaust velocity of 23,593 m/s).
The mass of the empty magazines, magazine support structure, and RCS fuel is more or less considered to be part of the payload (via the 4% downgrade trick). Naturally the mass of the nuclear pulse units proper is considered to be propellant mass (part of the 'wet mass'). Mars Mission Velocity Requirements Because NASA reports contain eternal optimism the report writers analyzed a Mars mission departing Terra in 1982, a mere 17 years from when the report was written.
This was to be a simplistic, inelegant, brute-force mission. All the maneuvers were done by rocket thrust, no fancy was used to reduce delta-V requirements.
They only figured the delta-V for two maneuvers in a given mission: Terra-to-Mars (ΔV out) and Mars-to-Terra (ΔV back). You can get away with this simplification if your spacecraft does not use multistaging.
The only reason the study authors used two delta-V measures instead of one is because the spacecraft mass changes so drastically. Lots of payload is consumed or left at Mars, particularly the two Aeronutronic landers. The mission assumes the spacecraft returns to a Terran elliptical orbit (Terran approach velocity of 11,000 m/s), have a reserve of 300 m/s RCS outbound and 460 m/s inbound, plus a 3% performance reserve. The crew is transferred from the spacecraft to Terra by a separate pickup vehicle based in orbit or on Terra (not carried by the Orion). For each mission, a Mars orbit capture period is included in the durations. So the scientists landed on Mars can do as much science as they possibly can in one and one-third months. Mission Delta-Vs Mission Duration ΔV out ΔV back ΔV total 450-day 9,100 m/s 12,500 m/s 21,600 m/s 350-day 14,000 m/s 14,600 m/s 28,600 m/s 240-day 18,000 m/s 16,800 m/s 34,800 m/s Remember these mission are brute-force.
NASA trajectory analysis can reduce the trip times by about 50 days or so by using swing-by maneuvers and other fancy mission optimizations. Others reduce the delta-V. For instance, NASA has a Venus swing-by maneuver which can do a 450 to 500 day Mars mission for a low-low total delta-V of 12,000 m/s. Figure 2 10 3 LB = 450 kg 10 6 LB = 450,000 kg In figure 2, the is the Orbit Departure Weight (IMLEO) and the is Total Payload. Abscissa is in units of one-thousand pounds (10 3 LB or 450 kg). Ordinate is in units of one-million pounds (10 6 LB or 450,000 kg) on the left, and in units of uprated Saturn V payloads on the right (127,000 kg). The total payload is assumed to be split 50-50 into the so-called 'round-trip' payload and the 'destination' payload.
The former is payload carried both to and from Mars, the latter is assumed to be all consumed or abandoned on Mars. 50-50 sounds arbitrary, but as it turns out lots of carefully planned mission studies have something very close to that split. The dotted line at the bottom contains the anemic chemically-powered miniscule mission previously referred to, helpfully labeled with 'Minimal Manned Landing Mission'. Rubbing salt in the wound, the report authors point out that this chemical rocket can only carry a small number of crew (requiring each person to have multiple functions, and increasing each person's work-load) and the rocket will need a high degree of expensive subsystem development and optimization because. Neither of which apply to a rocket driven by exploding nuclear bombs. Just in case you might have forgotten what you read in the last ten seconds, the report authors reiterate that one single standard Orion propulsion unit can perform any of the mission on the chart, no expensive development and optimization required. The report authors also wrote that at the top of figure 2, just because.
The two points marked 'Reference Designs' are based on specific payload breakdowns of about 145,000 kg. The 450-day reference design has an IMLEO of 522,000 kg (about x4 Saturn V payloads), the 250-day reference design has an IMLEO of 839,000 kg (about x7 Saturn V payloads). Remember the missions assume that the spacecraft does not carry any pickup vehicle. Once it returns to Terran elliptical orbit the crew is rescued by a separate vehicle stationed in orbit or on Terra.
If you examine the chart you will be interested to find that reducing the mission duration does NOT create an outrageous increase in IMLEO. You want a half-year Mars mission? Table 2 units are in pounds, 1 pound = 0.45 kg Table 2 contains the weight statements for the two reference designs. The 'radiation shelter' is the over-sized, found in all.
All long-duration spacecraft need storm cellar to protect the crew from solar proton storms. All Orion need extra-strength storm cellars because being propelled by the equivalent of a small nuclear war is not healthy for children and other living things.
The storm cellar mass is enough to reduce the radiation exposure from the Orion drive to only 0.5 Sievert per mission. This cellar will keep the dose from solar proton storms at 1 Sievert per mission.
The two reference missions have the same storm cellar mass. The 250 day mission has a shorter solar exposure than the 450 day mission, but a higher nuclear pulse exposure because more bombs are needed to shorten the trip. So it equals out. The propulsion periods when the crew has to retire to the storm cellar are usually short, from a few to about 20 minutes. The nuclear pulse units radiaton flux do not cause significant so the crew can access any part of the spacecraft a short time after propulsion shutdown.
The majority of the destination payload is the two (tail-sitter version). These were designed for a different spacecraft but as it turns out they fit on the 10-meter nuclear pulse rocket with only minor modification (payload spine has to be flattened). The Exploration Vehicle Configuration • Figure 3 click for larger image The consists of the supporting the at the top, next lower is the, then the Mars payload including the two. The bottom of the payload spine provides crew access to the propulsion module.
The lower part of the spine passes through the center of the, and encloses a repair-bay/spares-storage room (3 meters diameter by 7.6 meters tall). The payload spine is flattened in two places to accomodate the landers. If the required pulse unit magazine stack is too tall to fit under the Mars payload, the payload spine might have to be lengthened a bit. This is the only modification the Orion spacecraft is likely to need.
The personnel accomodations is 'upside down' because the entire spacecraft is a. The center of gravity (CG) of tumbling pigeon rotation moves aft as nuclear pulse units and landers are expended.
Options in Personnel Complement •. Figure 4 In figure 4, the is the Terran Orbit Departure Weight (IMLEO) just like figure 2, but the the is the number of crew members. The dotted line shows how rapidly the IMLEO rises with the number of crew for an 850 second multi-stage NERVA-style nuclear thermal rocket. The solid lines show how modest the IMLEO increase is for extra crew with an Orion boom-boom rocket.
Again the report writers harp on the fact that Orion is not subject to Every Gram Counts. With other anemic propulsion systems designers have to have the maximum payload determined at the start of the design process. The max payload is carved in stone. Once you have produced the spacecraft, adding more payload makes it impossible for the spacecraft to do the mission. With the mighty Orion on the other hand, adding more payload just means you just have to add a few more bomb magazines. Figure 4 illustrates a useful concept called ' loading factor'.
With the 400-day mission, adding an additional person increases the round-trip payload by about 4,500 kg, once you add in the extra food, water, and air. This additional mass needs additional propellant (pulse units) to propel it. The extra payload plus extra propellant increases the IMLEO by about 11,300 kg. So the loading factor is 2.5 to 1. Which means for every unit of extra payload mass you add, the IMLEO mass increases by 2.5 units.
In other words, for each additional 100 kg of inert weight added (telescopes, cornflakes, meteoroid protection, heavier structure) you need only add 150 kg of propellant to carry it through the journey! (100+150 = 250, which is a loading factor 2.5 to 1) No vehicle change is required, just add more propellant. For the 200-day mission the loading factor is more like 4.3 to 1. Options in Terra Return Conditions The reference design missions assume the spacecraft returns to Terra and uses a modest amount of thrust to enter an economical but wildly ellptical Terran orbit (approach velocity about 11,000 m/s). The missions do not waste payload mass by lugging along a little Terra reentry vehicle, they assume the crew will be rescued by a local vehicle stationed in Terra orbit or on a surface base. The Orion spacecraft will remain in elliptical orbit, available for restocking and reuse.
The report authors looked into two other options. • Orion spacecraft can be braked into a nice circular LEO orbit, if you are willing to carry additional propellant • If the priority is to save propellant and reduce IMLEO: you reduce propellant stock, carry a reentry vehicle, and the crew bails out in said vehicle as the Orion goes streaking past Terra on a one-way trip into the dark of the Solar system. The Orion passes by Terra at about 15,000 m/s relative.
Another study estimated that the mass for a reentry vehicle for 8 crew and 15,000 m/s is about 6,990 kg. Figure 5 In figure 5, the is the Terran Orbit Departure Weight (IMLEO) just like figure 2. The pair of bars at 50,000 ft/sec (15,000 m/s) is the propellant-saving 'abandon ship' option. The pair of bars at 35,000 ft/sec (11,000 m/s) is the standard reference missions. The pair of bars at Circular Orbit is the propellant-wasting circular LEO option.
As you can see the 'abandon ship' option has a lower IMLEO, though the mass of the reentry vehicle reduces the savings somewhat. And you cannot reuse the Orion. The circular orbit option does have a higher IMLEO, but not by an overwhelming amount. Single Launch Mission Capacity The reference missions assume multiple Saturn V launches to loft the components into orbit, where they are assembled. There is a way to use just one Saturn V launch. Unfortunately it involves using the Orion drive. In Terra's atmosphere.
The Orion is used as the top stage, starting at an altitude of 93 kilometers. The savings are substantial, the. But the thought of detonating *Two* *Hundred* *Nuclear* *Bombs* per launch will cause any nukeophobic person to scream in your face at the top of their lungs.
Especially if you are a politician and they are one of your constituents. The reference mission has one Saturn V launch to loft the Orion propulsion module, one launch for operational payload (personnel accomodations unit, remaining vehicle structure, some supplies), one launch for the Mars excursion modules, and a couple of launches carrying nuclear pulse units and miscellaneous small payloads. And as is typical for any space system, the direct operating costs are dominated by the cost of boosting the stuff into orbit. ', remember?
Reducing the number of Saturn V launches will cut the costs dramatically. Not to mention avoiding the nightmare of orbital assembly. Figure 6 Figure 6 shows a fully assembled Orion with a gross weight of 635,000 kg (1.4×10 6 LB) being boosted by a Saturn V with an uprated S-1C stage (since the standard S-1C cannot structurally handle that much payload, plus it needs more thrust and delta-V). The Orion ignites at an altitude of about 98 kilometers (53 nautical miles) and starts nuking away. This is high enough to protect the eyesight of idiots who cannot be bothered with warnings of not being too close to the launch site and staring directly at freaking nuclear explosions.
The Orion arrives at LEO with its mass reduced to 476,000 kg due to burning 159,000 kg of nuclear pulse units. The Orion then performs some shakedown maneuvers to get all the bugs out. After that the IMLEO mass is about 454,000 kg (1×10 6 LB).
Looking it up in we can see that is enough for quite a few mission options. It can do a total payload 250×10 3 LB (113,000 kg) in a 400 to 450-day mission returning to elliptical Terra orbit. Or even 430×10 3 LB (195,000 kg) if you are willing to settle for a 450 to 500-day minimum ΔV mission.
You will, however, need one additional launch to boost the crew into orbit. Trying to man-rate a nuclear Orion boost into orbit would be a nightmare. Just man-rating the Orion for deep-space operations is hard enough.
Since the initial Orion gross weight is 635,000 kg and the effective thrust is 3,500,000 N you can see the initial thrust-to-weight ratio during orbital boost is 0.55. This is a pretty low ratio compared to chemical rockets.
However the report assures us that detailed trajectory computations (that they do not elaborate on) reveal that for a 2,500 sec I sp rocket this thrust-to-weight ratio actually maximizes the amount of weight delivered to LEO. SYSTEM ADVANTAGES AND SYSTEM PROBLEMS There are other advantages to the Orion, besides the flexibility of a single design that the report authors keep mentioning every five minutes.
And of course there are disadvantages as well. Single Vehicle Operational Advantages Pretty much all the the other Mars mission spacecraft rely upon mult-staging, whether chemical or nuclear-thermal. But not Orion. One major advantage is a single-stage vehicles can do several test flights and shakedown cruises. You can't do that with multi-stage craft, not if they have to jettison parts of themselves as part of the test. Which means the the brave crew of a mult-stage craft have to set forth on a mission to distant Mars IN AN UNTESTED VEHICLE. Nothing works perfectly the first time.
Shakedown cruises allow debugging the systems, and allow the crew to become familiar with the peculiarities. It also allows any incipient or 'break-in' failures to be fixed before departure. Instead of becoming a life-or-death emergency 54.6 million kilometers from the closest help. Shakedown cruises also allow actual operating performance to be verified, the spacecraft's center of gravity can be trimmed, and unexpectedly high-loss or high-consumption expendables can be supplemented. Plus any unexpectedly discovered overwhelming problems will result in merely cancelling the mission, instead of a spacecraft lost with all hands in the black depths of space.
Test flights and shakedown cruises are standard procedure in the aircraft, marine, automotive, and other transportation fields. Setting forth on a long voyage without such test is unthinkable, except in the ad-hoc one-shot mult-stage rocket biz. Orion will allow a return to rational testing. Economic Advantages The flexibility of a single design raises its head again, reminding us that it is a vast cost saving to just make one design and reuse it. Instead of making and debugging a freaking new design for every single new mission.
This also costs savings in shakedown cruises, since the design bugs will have mostly been already discovered only the specific ship idiosyncrasies will have to be found. Another advantage is that nuclear pulse units are nicely dense, highly storable, and mostly trouble-free. Other propulsion systems use liquid hydrogen which is pretty much the exact opposite. Liquid hydrogen is annoyingly non-dense, requiring monstrously huge tanks and thus lots of booster vehicles and launch facilities.
Liquid hydrogen is not storable at all, suffering from and thus requiring power-hungry cryogenic cooling equipment. Boil-off also forces closely-spaced successive launches because the longer the hydrogen tanks loiter in orbit waiting for the rest the more hydrogen will be lost. Finally a spacecraft loaded with nice dense nuclear pulse units will have a which will protect it from atmospheric drag deorbiting it. The poor spacecraft loaded with liquid hydrogen will have to depart quickly or suffer a fiery crash.
But the most significant economic advantage is designing mission subsystems while being free of the tyranny of Every Gram Counts. Instead of spending tons of money and time trying to make featherweight (yet reliable) versions of all systems, you can just slap them together out of boilerplate like old Soviet spacecraft. When an additional 100 kg can be carried by simply loading an extra 148 kg of propellant, many subsystem problems become easier to solve. The main economic disadvantage of Orion is that the pulse units are shockingly expensive. Which is not surprising considering that they are loaded with highly-enriched weapons-grade uranium-235.
The official price of is classified, on the black market weapons-grade uranium has a. The back of my envelope says the propellant mass will be roughly 1.4% HEU. Liquid hydrogen on the other hand is about $0.70 US per kilogram.
Enroute Maintenance Capacity •. The Orion is far more maintainable enroute than other spacecraft.
Especially other nuclear ones. Orion has very low residual radioactivity, even after a large delta-V maneuver. The nuclear pulse units use beryllium oxide as a channel filler plus tungsten as propellant in order to sop up the neutrons heading for the spacecraft. The idea is it is better to use the neutron energy to accelerate the propellant instead of wasting them and allowing them to. It is safe for the crew to exit the storm cellar surrounding the flight station immediately upon propulsion shutdown. And only a short delay is needed for the neutron activation levels to die down to a safe level, allown crew access to the entire spacecraft.
Even the pusher plate. Nuclear thermal rockets, on the other hand, are neutron activation machines. Once the engine has been used it will be dangerously radioactive for decades to come.
The propellant is packaged in convenient discrete, dense containers instead of being large volumes of liquid hydrogen boiling away in cryogenically cooled propellant tanks. Trying to do maintenance inside a tank of -253°C LH 2 is a good way to die. Or trying to do maintenance nearby an LH 2 tank.
Orions have no cryogentic components (except for maybe the RCS) so all the ship components are easily accessable at temperatures normal for the space environment. This also means the structural members can be composed of ordinary steels, aluminum alloys and titanium instead of exotic hard-to-fix stuff. To take advantage of this easy access the Orion is designed with a large well-equipped repair bay and spare parts storage area. The ship can be worked on during coasting periods. Developmental Problems If this spacecraft is so great, why ain't NASA using them? Well, there are a few problems.
The report mentions that there are some uncertainties about the development of the nuclear pulse units, which unfortunately they cannot talk about because it is classified. They are after all basically nuclear weapons. All such programs have three classes of developmental problems: technical, programmatic (research and development), and poltical. Ordinary rocket projects usually have big problems with the first two classes, but the political problems are minor or nonexistent.
With Orion, the bulk of the problems are political. Orion has the technical problems well in hand, with lots of research and experimentation on ablation, explosive debris — pusher-plate interactions, and impulsive loading on structures. Orion's programmatic problems are mostly due to the fact that there is no immediate 'requirement' for a spacecraft with such a huge thrust and delta-V capacity. So the budgets are limited.
The report is of the opinion that if Orion spacecraft are made available, rocket scientists will be falling over each other to take advantage of the oodles of delta-V and thrust they provide. But Orion's political problems are where the poop hits the fan. The report says the problem 'rather obviously, stems from the fact that nuclear pulse propulsion uses in small scale the same energy source used for nuclear weapons'. Translation: the voters are going to scream 'OMG!!! YOU ARE TRYING TO MAKE A ROCKETSHIP THAT USES FREAKING ATOM BOMBS!!!
ARE YOU CRAZY??!?' A related political problem is that the forbids civilian nuclear detonations. Which is a problem for a spaceship. The report optimistically mentions that the treaty provides procedures for its own amendment.
Good luck with that. Figure 10 Launch scene displaying all the Terran launch requirements for the mission. Left: Saturn V lofting the payload including the Mars excursion modules.
Aeronutronic Mars Excursion Module This is from. The mission carries two of these, the preferred 'tail-sitter' version. The 'canted' version has problems, and doesn't fit as well on the Orion. Sadly the design assumed a Mars surface atmospheric pressure of 85 millibars.
The discovery by the Mariner 4 probe that the actual value was one tenth of this invalidated the design. This is, where he talks about the to the Aeronutronics MEM. The Aeronutronic MEM was sized for a 40 day stay on the Martian surface with three explorers. The fuel was a devil's brew of the appallingly corrosive, toxic, and carcinogenic (MMH) mixed with the ever-popular but beyond-insanely-dangerous.
At least it is a re-startable rocket. MMH is with any oxidizer, and FLOX is hypergolic with anything.
The reason for this fuel is they needed a specific impulse of at least 375 seconds, but liquid hydrogen fuel just takes up too much blasted room. The designers of the to the Aeronutronics MEM had the same problem, so they were forced to use FLOX as well. This is from • General Atomic division of General Dynamics GA-5009, Vol I • General Atomic division of General Dynamics GA-5009, Vol III • These is from a study of using Orion drive spacecraft to transport cargo to a Lunar base. Since this is Orion, the cargo capacity is huge. Each nuclear-pulse unit has a mass of about 141 kilograms. The Orion propulsion module carries 900 pulse units internally (126,900 kg), and additional units in magazines stacked on top of the module (92 units per magazine, 90 plus 2 spares. Empty magazine 181 kg, 92 units 12,972 kg, single magazine total 13,153 kg).
Pulse units are detonated at 0.86 second intervals to provide the nominal thrust of 3.5×10 6 Newtons. They have an effective specific impulse of 1,860 seconds (exhaust velocity of 18,250 m/s) The propulsion module has a mass of 90,946 kg, less the mass of the 900 internal pulse units (126,900 kg). This does not include the mass of magazine rack or any payload support structure. If I am adding correctly a 'wet' propulsion module with a full load of pulse units is 217,846 kg. Magazines will be added if 900 pulse units does not provide adequate delta V for the given mission (added in pairs to keep the center of gravity centered).
There were three designs. Orion Lunar Cargo Vehicles Orbital Ferry Surface Ferry Logistics Resuable? Yes yes NO Manned? Yes yes NO Cargo? Yes yes yes Passengers?
Yes yes NO Orbit Delivery? Yes yes yes Surface Delivery? NO yes yes Orion Orbital Ferry starts in Low Earth Orbit (LEO) with crew, cargo, and passengers. It travels to Low Lunar Orbit (LLO) under Orion power. In LLO chemical rocket cargo and passenger shuttles transfer cargo and passengers to and from the Orbital Ferry (carried along with the cargo, or sited at the Lunar base). The Orbital Ferry then travels back to LEO under Orion power, where it can be reused. Orion Orbital Ferry starts in LEO with crew, cargo, and passengers.
It travels to LLO under Orion power. It continues down to the Lunar surface. At an altitude of 6 kilometers it switches to chemical rocket power (because landing under Orion power will force the spacecraft to fly through the center of nuclear detonations, voiding the warrenty. And the ship). On the surface the cargo is unloaded by cranes and tractors. The spacecraft lifts off under chemical rocket power until it has delta Ved 640 m/s, then it switches to Orion power. It then travels back to LEO under Orion power, where it can be reused.
Orion Logistics Vehicle starts in LEO with cargo (no crew or passengers). It travels to LLO under Orion power (strictly under remote control/autopilot). There are two flight plans from this point. In the first, the vehicle parks in LEO. The second stage detaches and lands under chemical power. The spent Orion stages is abandoned in orbit. In the second the entire vehicle starts landing under Orion power.
Near the surface the second stage detaches and lands under chemical power while the spent Orion first stage crashes into the Lunar surface at about one kilometer per second. The Orion stage obviously cannot be reused but the base might be able to salvage the wreckage. The second plan utilizes the awesome might of Orion more fully at the cost of a more risky and complicated flight plan. The second flight plan drastically lowers the wet mass of the vehicle, allowing a much smaller Saturn or solid rocket booster to loft it into orbit.
The report assumes the Cargo Modules will have a payload density of 272 kg/m 3. The modules have a loaded mass of 100,000 kg, a diameter of 10 meters (5 m radius), and a height of 4.7 meters. These are sized so they can be boosted into orbit by a Saturn V. That is, a Saturn V can carry one (1) cargo module into orbit. The cargo module stack is tied together with wire cables to keep it in compression. The reference designs have a maximum of four cargo modules in a stack, but presumably it could be higher. The report estimates that for a manned mission: if the lunar base stay time is six months, support is 1,800 kg pwer man-year, and a ferry thrust-to-weight ratio of 0.15, the ferry could transport 400 passengers with the required support.
But the report skips over the problem of passenger accomodations during the trip (particularly shielding them from the Orion drive radiation). Orbit-to-Orbit Lunar Ferry Remember, this starts in Low Earth Orbit (LEO) with crew, cargo, and passengers. It travels to Low Lunar Orbit (LLO) under Orion power. In LLO chemical rocket cargo and passenger shuttles transfer cargo and passengers to and from the Orbital Ferry (carried along with the cargo, or sited at the Lunar base). It then travels back to LEO under Orion power, where it can be reused.
The ferry carries one. It has four cargo modules. The conical structure below the Command Module is the command module adapter section.
It supports the Command Module and contains the auxiliary propulsion system. That is used for thrust vector correction and vernier velocity. It uses nitrogen tetroxide, and 50% hydrazine + 50% unsymmetrical dimethylhydrazine (UDMH). Each motor has 5,000 newtons of thrust. Maximum payload mass fraction is when the thrust-to-weight ratio was 0.15, which is seven cargo modules.
The maximum possible was eight cargo modules. My off-the-cuff estimate of the ship mass. OtO Ferry Mass Schedule Component Mass kg Propulsion Module 90,946 Internal Pulse Units (x900) 126,900 x6 Magazines 78,918 x1 Command Module (with 3 crew) 27,510 x20 passengers 2,000 x2 Passenger Modules 5,780 x2 Passenger Mod Life Support 1,000 x4 Cargo Modules 400,000 Command Module Adapter??? X1 Passenger Shuttle (no crew, no passengers, no Life Support) 6,340 Pass Shuttle Life Support 1,400 x1 Cargo Shuttle 3,520 Cargo Shuttle Life Support 400 TOTAL 744,114 The following is me playing number games, no guarantee of accuracy given. I figure with 92 pulse units per magazine and six magazines plus the 900 internal pulse units the OtO Ferry is carrying 1,452 pulse units. 1,452 @ 141 kg each means 204,732 kg of propellant, for a starting mass ratio of 1.38.
The first leg of the trip from Earth Departure to Lunar Orbit Capture takes a total of 4,296 m/s of delta V. Which means the required mass ratio for the first leg is 1.265.
So the required propellant fraction is 0.2097. Wet mass is 744,114 kg so the total propellant (nuclear pulse units) expended for the first leg is 744,114 * 0.2097 = 156,073 kg. Round up to a whole number of 141 kg pulse units to 156,087 kg (1,107 pulse units). In Lunar orbit, the cargo and the passengers are ferried to the surface and are now no longer part of the OtO Ferry mass.
Neither is the mass for the passenger life support consumables in the Passenger Modules and Passenger Shuttle. Ditto the crew life support in the Passenger and Cargo shuttles. The empty ferries are retained, because Orion has delta V to spare. The new wet mass is 182,141 kg, and dry mass 133,496 kg. The second leg of the trip from Plane Change to Earth Orbit Capture takes a total of 4,735 m/s of delta V. R = e (Δ v/V e) which means the required mass ratio for the second leg is 1.265. P f = 1 - (1/R) so the required propellant fraction is 0.229.
Wet mass is 182,141 kg so the total propellant expended for the second leg is 182,141 * 0.229 = 41,624 kg. Round up to a whole number of pulse units to 41,736 kg (295 pulse units). The OtO Ferry is now in Terra orbit with 49 pulse units to spare.
• Orion LEO to Lunar Orbit Ferry Note access tube connecting command module and passenger modules click for larger image •. Orbit-to-Surface Lunar Ferry Remember this starts in LEO with crew, cargo, and passengers.
It travels to LLO under Orion power. It continues down to the Lunar surface. At an altitude of 6 kilometers it switches to chemical rocket power. On the surface the cargo is unloaded by cranes and tractors. The spacecraft lifts off under chemical rocket power until it has delta Ved 640 m/s, then it switches to Orion power. It then travels back to LEO under Orion power, where it can be reused.
The ferry carries one but no Passenger Modules. It has three cargo modules. The landing module uses LOX/LH 2 chemical rockets (specific impulse of 430 seconds). Both the chemical thrust chambers and landing gear are retractable, otherwise the shock from the nuclear pulse charges would snap them off (technical term is 'impingement loads'). When deployed the thrust chambers are canted with an angle of 30°. Scott Lowther is of the opinion that the landing gear does not appear to be capable of extending far enough to clear the pusher plate. The central firing tube protruding from the bottom of the pusher plate is in a most inconvenient location.
Since the entire clanking mess lands, the spacecraft does not have to carry along any cargo or passenger shuttles. • Orion LEO to Lunar Surface - No Staging click for larger image •. Manned Spacecraft Modules These are used in the Orbit-to-Orbit Lunar Ferry and Orbit-to-Surface Lunar Ferry. The Logistics Vehicle is unmanned so it needs them not. The Command Module is shielded to be a, and also a shelter from Orion radiation during maneuvering sequences.
It is sized for a crew of three. The upper section is the flight deck, the lower is the crew's accomodations. During Orion Drive thrust events and solar proton storms the lower section is also used as the storm cellar for the passengers housed in the Passenger Modules. The upper compartment is sized at 5 m 2 (50 ft 2) for a crew of three, while the lower is sized at 5 m 3 (180 ft 3) per man, assuming that no more than two of the crew is off duty at one time. Of the 27,510 kg mass of the Command Module, fully 22,380 kg is the radiation shielding. The anti-neutron layer is polyethylene, the anti-gamma-ray layer is depleted uranium.
The side and top shielding is meant to protect from solar storms, the bottom shielding is the shadow shield protecting from the Orion drive. The side and top shielding is 25 cm of polyethylene (25 g/cm 2). The bottom shielding is 100 cm of polyethylene (110 g/cm 2) and 29 cm of depleted uranium (55 g/cm 2). The requirement is to limit an integrated dose to 0.5 Sievert during the nuclear-pulse detonations. Since the Passenger Modules are unshielded, the maximum number of passengers is limited to how many can cram into the lower part of the Command Module.
So the design assumes 20 passengers and two Passenger Modules with a capacity of 10 passengers each. Even though the Orion can carry more than two Passenger Modules, there isn't enough room in the storm cellar for more. The Command Module can be stretched higher to expand the passenger storm cellar if you simply must add another Passenger Module or two (higher instead of wider in order to minimize diameter of shadow shield). Each additional passenger will add 114 kg to the mass of the Command Module (mostly for radiation shielding, the rest is mostly abort propulsion fuel). Actually to keep the spacecraft balanced it will probably have to have an even number of Passenger Modules.
Passenger Modules have enough life support to keep their 10 passengers alive for five days. Each passenge has 5 cubic meter of volume. The upper deck is the sleeping quarters, the lower is for work, eating, and recreation. The total mass is 4,390 kg. The air pressure is 7 psi. The Command Module's abort propulsion system can provide 3 g's for three seconds using a solid propellant with a specific impulse of 270 seconds. The Command Module's crew support mass includes space suits, tools, and crew's personal gear.
Lunar Logistics Vehicle Remember this starts in LEO with cargo (no crew or passengers). It travels to LLO under Orion power (strictly under remote control/autopilot).
There are two flight plans from this point. In the first, the vehicle parks in LEO. The second stage detaches and lands under chemical power. The spent Orion stages is abandoned in orbit.
In the second the entire vehicle starts landing under Orion power. Near the surface the second stage detaches and lands under chemical power while the spent Orion first stage crashes into the Lunar surface at about one kilometer per second.
The Orion stage obviously cannot be reused but the base might be able to salvage the wreckage. The second plan utilizes the awesome might of Orion more fully at the cost of a more risky and complicated flight plan. The second flight plan drastically lowers the wet mass of the vehicle, allowing a much smaller Saturn or solid rocket booster to loft it into orbit. It has zero Command Modules, zero Passenger Modules, and four Cargo Modules. There is a rudimentary Forward Module with a few attitude jets and the autopilot, and a chemical rocket landing stage. The landing stage contains the landing gear, which is lower mass than the Orbit-to-Surface Lunar Ferry since it does not have to support the additional mass of the Orion drive.
The single chemical engine is centered in the stage instead of being canted at 30° since the Orion drive is jettisoned. • Orion LEO to Lunar Surface - Staging (Unmanned) click for larger image •. AUXILIARY VEHICLES Passenger Shuttle It was assumed that each passenger shuttle would be able to make two trips for each Orion ferry mission. No, I'm not sure what they mean by 'trip'. Could be from Orion to surface to Orion, or just Orion to surface. The passenger shuttle consists of three components: passenger compartment, crew/command cockpit, and propulsion module. The passenger shuttle can transport twenty passenger.
The passenger compartment is sized assuming 2.5 m 3 per passenger, and a single passenger deck. This gives a diameter of six meters.
The life-support system is open loop since usage time and frequency of use does not justify the expense of a closed-system. System mass requirements are 5.2 kg per man-day, including fixed container weights. Passenger support allowance based on an estimate of 50 kg/man for space suits and personal gear. The command cockpit is for a crew of two, and can operate completely independent of the passenger compartment (if some idiot passenger vents the compartment to space the passengers will all die but the crew will be just fine.). The propulsion module uses LOX and LH 2 with a specific impulse of 430 seconds. The tanks are sized for just landing, it assumes the tanks can be refilled on the Lunar surface at the Lunar base or propellant depot. Expansion of 'Command Cockpit' entry in table above Cargo Shuttle A 2 crew command cockpit is attached to the propulsion module.
It has the same mass as the cockpit on the passenger shuttle, but with a contingency mass of 5 percent. Mass of the cargo shuttle is estimated to be 3,520 kilograms, not counting payload.
The cargo landing system was specified to handle up to ten Cargo Modules (one million kilgrams total cargo), presumably with two or more shuttles. With one shuttle, the cargo stack would be 47 meters tall (about 150 feet) which would be a formidable challenge to unload on the Lunar surface. USAF 4000 Ton Orion Pusher Plate Diameter 26 m Height 78 m Wet Mass 3,629,000 kg (4,000 short tons) Payload Shell Volume 11,000 m 3 Pulse unit mass bare unit 1,150 kg Pulse unit mass w/support rollers, etc. 1,190 kg Pulse unit dim. 80 cm dia × 87 cm high Pulse unit detonation dist. 52.4 m ± 2 m Pulse unit specific impulse 4,300 sec effec: 3,600 sec Detonation delay 1.1 sec Pulse Unit Storage Number storage levels 4 Number conveyors per level 2 Number pulse units per conveyor 140 Total pulse unit capacity 1,120 15 km/s ΔV 30 km/s ΔV Average initial accel 1.25 g 1.25 g Total engine weight (dry) 1,233,000 kg 1,252,000 kg Number pulse units 926 1,500 Pulse system mass (incl.
Coolant) 1,280,000 kg 2,068,000 kg Payload mass 1,115,000 kg 308,000 kg Most of the information and images in this section are from. I am only giving you a 'Cliff Notes' executive summary of the information, and only a few of the images and those in low resolution. If you want the real deal, get a copy of APR v2n2. Orion drive spacecraft scale up quite easily. However, unlike other propulsion systems, they do not scale down gracefully.
Surprisingly it is much more of an engineering challenge to make a small Orion. It is difficult to make a nuclear explosive below a certain yield in kilotons, and small nuclear explosives waste most of their uranium or plutonium. But it is relatively easy to make them as huge as you want, just pile on the megatons. So in the 1960's when General Atomic made their first pass at a design, it was for a titanic 4,000 ton monster. By this time they realized that they would never get permission to launch an Orion from the ground under nuclear-bomb power, so the baseline was Mode III: a gargantuan chemical booster boosts the fully loaded Orion into LEO. So it does not carry the pulse units required to achieve orbit. For that the engine section would have to be taller.
This became the basis for the. They took the 11,000 cubic meters of the payload shell and stuffed it full of weapons. Pulse unit loader mechanism There is one of these on each of the four floors. Each has two 'breech chambers', either of which can be this floor's section of the compressed-gas cannon barrel. While one chamber is closed and busy being a barrel section, the other chamber is open and being loaded with a pulse unit. At any point in time, on each floor there are closed chambers ensuring that the cannon barrel is complete. But only one floor at a time has a pulse unit loaded in the chamber, the other floors have empty chambers.
The chambers are loaded alternating between the two conveyor tracks they share the floor with. Breech chamber lock holds the chamber shut when the barrel is pressurized •.
N o1: Chamber assembly rotated so that the left chamber is over the cannon barrel. N o2: Restraining cylinder gets out of the way, positioning cylinder touches next pulse unit N o3: Conveyor reel pulls trolley, moving clutch of pulse units in general and next pulse unit in particular into position. Positioning cyclinder contracts in tandem with trolley. N o4: Restraining cylinder advances to lock all the pulse units in place except for the next pulse unit. Chamber assembly rotates to put right chamber over cannon barrel, and left chamber opens up N o5: Positioning cylinder moves out of the way, and loading cylinder pushes next pulse unit into left chamber N o6: Pulse unit is firmly seated inside left chamber N o7: Left chamber doors close over the pulse unit N o8: Chamber assembly rotates to put loaded left chamber over the cannon barrel. 10 meter plate is standard Orion 20 meter plate is the Saturn mission red: engine (pusher-plate and shock absorbers) gold: magazines of nuclear charges LEO Mass (metric tons) ΔV (km/s) B = 0.01 B = 0.10 60 5,916 7,585 80 11,819 17,117 90 16,719 26,001 100 23,667 39,842 120 47,524 96,510 This is from The second half of the report looked into a manned mission to Saturn, using an Orion drive spacecraft with a 20 meter diameter pusher plate. The specific impulse was estimated to be 3,000 to 3,150 seconds (they appear to be using 30,000 to 31,500 m/s for exhaust velocity, instead of 29,430 to 309,015 m/s).
The table to the left is from the report. The propulsion system, as with all Orion drives, is more or less a pusher-plate, lots of shock absorbers, and a variable amount of magazines loaded with nuclear charges. The mass of the pusher plate and shock absorbers is always the same. The amount of nuclear charges depends upon how much delta-V you need for the mission.
The more charges, the higher the mass ratio, and the higher the delta-V. The dry mass of the propulsion system is: Mdry = A + (B * Mp) where Mdry: propulsion system dry mass (kg) A: fixed propulsion system mass (kg) B: propulsion system mass dependant on propellant mass Factor (kg / kg*Mp) Mp: propellant mass (kg) (B * Mp): variable propulsion system mass (kg) 'Fixed propulsion system mass' is the part of the mass of the engine that is the same regardless of how much propellant is loaded. Basically the mass of the pusher plate and shock absorbers. They estimate A to be 358,000 kilograms.
'Propulsion system mass dependant on propellant mass' is the mass that varies with the total propellant mass. Each nuclear charge has part of its mass devoted to the tungsten propellant, the rest is devoted to the fission explosive device, the channel filler, the enclosing metal cannister, etc. Plus the magazines that hold a couple of hundred nuclear charges each, the racks holding the magazine, etc. Obviously the more tungsten propellant you carry; the more fission explosive, magazines, magazine racks and other whatnot will also be carried. The report estimates that B factor will be from 0.01 to 0.10, probably nearer to 0.01.
This means for every kilogram of tungsten propellant loaded, the ship will also be loaded with about 0.01 kilograms of nuclear explosives, channel filler, cannisters, magazines, magazine racks, etc. The mass of the propellant ( Mp) is not added in, since the equation is to calculate the dry mass. The payload mass is estimated to be about 391 metric tons. This includes the habitat module, landing vehicles, 20 crew, and life-support expendables for 20 crew for the mission duration. I did some work on a spreadsheet and I suspect the 391 MT figure is for the 100 km/s delta-V mission. For the lower ΔV missions the payload mass has to be higher to make the math work. Which makes sense, lower ΔV means longer mission time, which means the mass of the life-support consumables has to go up.
The following is from my calculations, not from the report. Be told that I have been known to make silly math mistakes, so take this under advisement.
It assumes that the exhaust velocity is 31,500 m/s, and the fixed engine mass is 358,000 kg. Payload mass is adjusted from the 391 MT figure to make the math work, I assume it is due to change in mass of consumables with change in mission time.
Keep in mind that a mass ratio higher than 20.0 is really hard to do. Saturn Mission Mass Budget (B = 0.01) ΔV Mass Ratio Propellant Fraction LEO mass (Wet Mass) (kg) Propellant Mass (kg) Dry Mass (kg) Variable Propellant Mass (kg) Payload Mass (kg) 60,000 6.72 0.85 5,916,000 5,035,356 880,644 50,354 472,291 80,000 12.68 0.92 11,819,000 10,886,582 932,418 108,866 465,552 90,000 17.41 0.94 16,719,000 15,758,784 960,216 157,588 444,628 100,000 23.92 0.96 23,667,000 22,677,466 989,534 226,775 404,759 120,000 45.13 0.98 47,524,000 46,470,929 1,053,071 464,709 230,362 The exploration of the moons of Saturn will require in-situ resource utilization. This will make the focus of exploration the moons Mimas, Enceladus, Titan, and Iapetus. These have the highest probability of readily available water ice, aka '. A water-cracking plant will be delivered to one of the moons to produce fuel (Mimas or Titan, probably Mimas). This will fuel the landers. The landers will have LOX/LH 2 chemical rockets for landing and lift-off.
They will be delivered from the Orion spaceship into the orbit of their target moon by nuclear electric propulsion Orbital Transfer Vehicles (OTV). The ion drives will be nuclear powered because at Saturn's distance from Sol, the available solar power is (meaning a solar power array that gets x amount of power at Terra will have to be one hundred times larger to get the same amount of power at Saturn). The ion drives will use hydrogen instead of xenon for propellant since xenon is real hard to find, anywhere. • • • Orion Battleship Pusher Plate Diameter 26 m Height 78 m Wet Mass 3,629 tonnes (4,000 short tons) Payload Shell Volume 11,000 m 3 Pulse unit specific impulse 4,300 sec effec: 3,600 sec Detonation delay 1.1 sec Crew 120 Hypersonic re-entry vehicles (20 crew) 6 2-Crew Space Taxi 12 15 km/s ΔV 30 km/s ΔV Average initial accel 1.25 g 1.25 g Total engine weight (dry) 1,233 tonnes 1,252 tonnes Number pulse units 926 1,500 Pulse system mass (incl. Coolant) 1,280 tonnes 2,068 tonnes Payload mass 1,115 tonnes 308 tonnes Weapons Mk-42 5-inch naval turret x3 Missiles w/20 megaton warheads x500 Missiles Silos 3 banks of 30 each 90 total Casaba Howitzer bolts Several hundred Casaba Howitzer Launchers x6 20mm CIWS turret x6 When the Orion nuclear pulse propulsion concept was being developed, the researchers at General Atomic were interested in an interplanetary research vessel.
But the US Air Force was not. They thought the would be rightsized for an interplanetary warship, armed to the teeth.
And when they said armed, they meant ARMED. It had enough nuclear bombs to devastate an entire continent (500 twenty-megaton city-killer warheads), 5-inch Naval cannon turrets, six hypersonic landing boats, and several hundred of the dreaded — which are basically ray guns that shoot nuclear flame (the technical term is 'nuclear shaped charge'). This basically a 4,000 ton Orion with the entire payload shell jam-packed with as many weapons as they could possibly stuff inside.
Keep in mind that this is a realistic design. It could actually be built.
The developers made a scale model of this version, which in hindsight was a big mistake. It had so many weapons on it that it horrified President Kennedy, and helped lead to the cancellation of the entire Orion project. The model (which was the size of a Chevrolet Corvette) was apparently destroyed, and no drawings, specifications or photos have come to light. Has painstakingly done the research to recreate this monster. If you want all the details, run, do not walk, and purchase a copy of.
He also made a for Fantastic Plastic, you can order one. • Drawing by 2010.
Click for larger image • Drawing by 2013. Note redesigned hypersonic landing boat. Click for larger image • Drawing by 2013.
Click for larger image • By 1963, an Orion nuclear lift-off was not allowed. Here is the concept of using a chemical-powered booster to loft the Orion Battleship into orbit. Drawing by 2013. Click for larger image • Both the and the Orion Battleship are huge. Drawing by 2013. Click for larger image •.
Artwork by 2013 • Artwork by 2013 • Mk-42 5-inch naval turret flanked by two Casaba Howitzers. Note the hatch doorway, this gives a sense of scale. Artwork by 2013 • Artwork by 2013 • The blocky structures next to each Casaba Howizer is the reloading ports. Artwork by 2013 • Four space taxis and two hypersonic re-entry vehicles.
Artwork by 2013 • • • • • • • Artwork by Winchell Chung (me). Click for larger image • Artwork by Winchell Chung (me). Click for larger image • Artwork by Winchell Chung (me). Click for larger image • Artwork by Winchell Chung (me). Click for larger image • Artwork by Winchell Chung (me).
Click for larger image • Artwork by Winchell Chung (me). Click for larger image • Artwork by Winchell Chung (me).
Click for larger image •. But we could have been so much farther along.
After the publication of George Dyson’s book Project Orion, and a few specials, a lot of people know that in the early 1960s DARPA investigated the possibility of a nuclear-pulse-detonation (that is, powered by the explosion of nuclear bombs) spacecraft. Preceding but also concurrently developed with Apollo, this extremely ambitious project had unbelievable payload capability.
Where Apollo at 3,500 tons could only put two tons on the Moon, the smaller Orion (about the same total mass, 4,000 tons) could soft-land 1,200 tons (600 times as much) on the Moon, and the larger (only three times as heavy as Apollo, or 10,000 tons) could soft-land 5,700 tons (nearly 3,000 times as much) on the Moon, or take 1,300 tons of astronauts and consumables on a three-year round-trip to Saturn and back! 1 The fission powered Orion could even achieve three to five percent the speed of light, though a more advanced design using fusion might achieve eight to ten percent the speed of light.
Most assume the program was cancelled for technical problems, but that is not the case. Few know how seriously the idea was taken by the top leadership of the US Air Force. Because internal budget discussions and internal memoranda are not generally released and some only recently declassified, almost nobody knows how close Strategic Air Command (SAC) was to building the beginning of an interstellar-capable fleet. Had the personalities of the Air Force’s civilian leadership been different in 1962, humanity might have settled a good part of the inner solar system and might be launching probes to other stars today. We might also have had the tools to deflect large asteroids and comets. Recently declassified internal budget documents show that, in 1962, the US Air Force had plans to build entire fleets of giant Orion spacecraft, and was prepared to commit almost 20 percent of its requested space budget from 1963 to 1967 to its realization. It is one thing to hear Freeman Dyson, the eminent physicist and Project Orion veteran, say that the “end result [of Project Orion] was a rather firm technical basis for believing that vehicles of this type could be developed, tested, and flown.
The technical findings of the project have not been seriously challenged by anybody. Its major troubles have been, from the beginning, political.” 2 It is another to have that confirmed by Air Force internal memoranda. America’s near-brush with Starfleet began with Donald Mixson and Fred Gorschboth, two young captains assigned to the Air Force Special Weapons Center at Kirtland Air Force Base. Their job was to investigate the military implications of Orion nuclear pulse propulsion technology, and wargame out a military concept for use. They developed a plan for a three-tiered space force of dozens of Orion spacecraft deployed in either low, geosynchronous, or lunar orbit squadrons.
This fleet would hold both nuclear surface attack missiles to provide a survivable deterrent without risk of being destroyed by a first strike, as well as space-based ICBM interceptors and mines (an early vision of the Strategic Defense Initiative) that could defend the United States from a Soviet attack in the event deterrence failed. 3 In late 1959, Captain Mixon laid out the evidence for General Thomas Power, the commander in chief of SAC, and obviously convinced him. On January 21, 1961, General Power signed a SAC requirement for a “Strategic Earth Orbital Base” (SEOB) based on the Orion propulsion system and roughly following the space force deployment concept.
The SEOB would be “capable of accurate weapon delivery” to “include the capability to attack other aerospace vehicles or bodies of the solar system occupied by an enemy.” The SEOB would also be able to orbit “extremely heavy useful payloads” on the order of 5,000 tons. 4 General Power was not out there alone. He had the full support of the Chief of Staff of the Air Force, General Curtis E.
Writing in a 1962 letter to Power, he said, “I share your views regarding the potential of ORION.” 5 Nor was it just talk: both the SAC commander and the US Air Force Chief of Staff were willing to put their money where their mouth was. In 1962, funding for the SEOB and Orion propulsion development together accounted for $1.36 billion (over $10 billion in 2014 dollars), or 18 percent of the total Air Force space development budget for fiscal years 1963–1967, as requested by LeMay in his Air Force Space Program. 6 Just what was the capability SAC wanted? A ten-meter Orion ship could get a crew of eight men from Earth to Mars orbit and back in 150 days (chemical missions would require 300–450 days round trip at best) in a vehicle weighing just under 1,000 tons with a 100-ton payload. The SEOB, with a payload capability of 5,000 tons, was akin to the “Advanced Interplanetary Orion” design developed later during Project Orion, which had a gross mass of 10,000 tons and could take 5,300 tons to the same Mars orbit. 7 So who killed Starfleet?
Here is how it went down: Secretary of the Air Force Eugene Zuckert approved LeMay’s space program but, contrary to his own support of it, refused to request funding for it from DOD, knowing that Secretary of Defense Robert McNamara would not be supportive. 8 Upon hearing that Orion would not be funded, General Power wrote to the Defense Director of Research and Engineering, Dr. Harold Brown, and argued that “the capability to launch and maneuver truly large payloads [in space] could provide the operational flexibility [that] could be a decisive factor in achieving scientific and commercial, as well as military supremacy.” 9 Dr.
Brown, the man responsible to McNamara for keeping Air Force research and development constrained to Kennedy Administration wishes, responded, “This development program would be a high risk one If we accept the possibility that military operations will require large maneuverable payloads in space, it is still far from clear that substantial investment in ORION is warranted now.” 10 And so, here we are in 2015. Fifty-three years later we still have nothing close to Orion. Rather than get to Mars and back in 150 days, with 5,000 tons, we can’t even contemplate a three-person capsule to Mars for another couple decades. Brown was recommending what he thought was responsible at the time, and recommending spending-averse budgets to minimize risk over the advice of the capability-driven military minds. Perhaps he, like many modern voices, felt the need to fear or temper the perceived rapaciousness and expansionism of such men as LeMay and Power.
With their vision would have come challenges to stability and perhaps increased risk of a nuclear conflict on Earth. We may have bought ourselves a little near-term stability, but it was not without cost. Secretary McNamara’s and Dr. Brown’s conservatism and lack of vision has left humanity in a local minima, trapped in a gravity well, unable to access the vast wealth of the inner solar system, and left the life on our entire planet bare and defenseless against what has emerged as a credible threat: asteroids and comets. We have traded the grand visions of 1962 for a much more tawdry reality, one where instead of going to space in ships with large crews that could roam the inner solar system in voyages measured in months, and would have laid the foundation for humans to reach other stars, our species has accepted small tin cans that may just be able to send a handful of specialists to Mars before the Apollo lunar landing centennial.
Had the US Air Force not been gelded in 1962, humanity would today be reaching for the stars. Note: This essay is based in part on a presentation by Major Ziarnick given to the Tennessee Valley Interstellar Workshop at Oak Ridge, TN in November 2014. A video of the presentation can be found at: The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Air Force, the Department of Defense, or the US Government Endnotes • George Dyson, Project Orion (New York: Penguin Books, 2003), 55. • Freeman Dyson, “Death of a Project,” Science, Vol 149, No 3680, 9 July 1965, 141.
• Captain Frederick F. Gorschboth, Counterforce from Space (Kirtland AFB, NM: Air Force Special Weapons Center, 1 August 1961) Original classification SECRET. Now declassified. Captain Gorschboth’s work is representative of the space force concept. Captain Mixson’s work is not yet declassified. • General Thomas S.
Power, Strategic Earth Orbital Base, Strategic Air Command Qualitative Operational Requirement, 21 January 1961. Original classification SECRET. Document is now declassified. • General Curtis E. LeMay, Vice Chief of Staff, to General Thomas S. Power, commander, Strategic Air Command, 16 July 1962. Original classification SECRET.
Document is now declassified. Carter, An Interpretive Study of the Formulation of the Air Force Space Program, 4 Feb 1963. Original classification SECRET.
Document is now declassified. • George Dyson, Project Orion, 55.
Cantwell, The Air Force in Space Fiscal Year 1963 (Washington, DC: USAF Historical Division Liaison Office, December 1966). Classified TOP SECRET. Excerpt is declassified, 6. • General Thomas S. Power, commander, Strategic Air Command, to Dr. Harold Brown, Director of Defense Research and Engineering, 3 November 1962.
Original classification SECRET. Document is now declassified. Harold Brown, Director of Defense Research and Engineering, to General Thomas S. Power, commander, Strategic Air Command, 15 November 1962.
Original classification SECRET. Document is now declassified.
Emphasis original. • Pre-production version of Discovery spacecraft for movie 2001 A Space Odyssey. The Orion propulsion system was later dropped.
It has heat radiators for no obvious reason, Orion drives don't need 'em. Click for larger image. Like everything else in 2001, the good ship Discovery passed through many transformations before it reached its final shape. Obviously, it could not be a conventional chemically propelled vehicle, and there was little doubt that it would have to be nuclear-powered for the mission we envisaged. But how should the power be applied?
There were several alternatives — electric thrusters using charged particles (the ion drive); jets of extremely hot gas (plasma) controlled by magnetic fields, or streams of hydrogen expanding through nozzles after they had been heated in a nuclear reactor. All these ideas have been tested on the ground, or in actual spaceflight; all are known to work. The final decision was made on the basis of aesthetics rather than technology; we wanted Discovery to look strange yet plausible, futuristic but not fantastic. Eventually we settled on the plasma drive, though I must confess that there was a little cheating.
Any nuclear-powered vehicle must have large radiating surfaces to get rid of the excess heat generated by the reactors — but this would make Discovery look somewhat odd. Our audiences already had enough to puzzle about; we didn’t want them to spend half the picture wondering why spaceships should have wings. So the radiators came off. There was also a digression — to the great alarm, as already mentioned, of the Art Department — into a totally different form of propulsion. During the late 1950’s, American scientists had been studying an extraordinary concept (“Project Orion”) which was theoretically capable of lifting payloads of thousands of tons directly into space at high efficiency. It is still the only known method of doing this, but for rather obvious reasons it has not made much progress.
Project Orion is a nuclear-pulse system — a kind of atomic analog of the wartime V-2 or buzz-bomb. Small (kiloton) fission bombs would be exploded, at the rate of one every few seconds, fairly close to a massive pusher plate which would absorb the impulse from the explosion; even in the vacuum of space, the debris from such a mini-bomb can produce quite a kick.
The plate would be attached to the spacecraft by a shock-absorbing system that would smooth out the pulses, so that the intrepid passengers would have a steady, one gravity ride — unless the engine started to knock. Although Project Orion sounds slightly unbelievable, extensive theoretical studies, and some tests using conventional explosives, showed that it would certainly work — and it would be many times cheaper than any other method of space propulsion. It might even be cheaper, per passenger seat, than conventional air transport — if one was thinking in terms of million-ton vehicles. But the whole project was grounded by the Nuclear Test Ban Treaty, and in any case it will be quite a long time before NASA, or anybody else, is thinking on such a grandiose scale. Still, it is nice to know that the possibility exists, in case the need ever arises for a lunar equivalent of the Berlin Airlift. When we started work on 2001, some of the Orion documents had just been declassified, and were passed on to us by scientists indignant about the demise of the project.
It seemed an exciting idea to show a nuclear-pulse system in action, and a number of design studies were made of it; but after a week or so Stanley decided that putt-putting away from Earth at the rate of twenty atom bombs per minute was just a little too comic. Moreover — recalling the finale of Dr. Strangelove — it might seem to a good many people that he had started to live up to his own title and had really learned to Love the Bomb. So he dropped Orion, and the only trace of it that survives in both movie and novel is the name. From Lost Worlds of 2001 by Sir Arthur C. Clarke (1972) •. • Reusable Nuclear Shuttle ΔV 13,000 m/s? Specific Power 45.9 kW/kg?
(45,870 W/kg?) Thrust Power 1.4 gigawatts? Propulsion NTR-solid Specific Impulse 816 s Exhaust Velocity 8,000 m/s Wet Mass 170,000 kg? Dry Mass 30,000 kg? Mass Ratio 5.3?
Mass Flow 41.7 kg/s Thrust 344,000 n? Initial Acceleration 0.16 g Payload 8-burn 45,000 kg? Payload 4-burn 58,000 kg? Length 49 m Diameter 33 m This is a 1970's era NASA concept for a. Note that in many of the images the shuttle has a crew module perched on top. Design is very similar to the. David Portree wrote a nice history of the nuclear shuttle:.
Phase I design was for an expendable vehicle with a 200,000-pound-thrust NERVA II engine. It was to be used for several rocket stages on their planned Mars mission vehicle. The Phase II design is what is pictured below the Class 1 Reusable Nuclear Shuttle (RNS). It had a a 75,000-pound-thrust NERVA I engine and a payload capacity of 50 tons.
NASA had an optimistic RNS traffic model calling for 157 Terra-Luna flights between 1980 and 1990 by a fleet of 15 RNS vehicles. The has a mass of 9,000 kg. The NERVA engine is 18 meters long and 4.6 meters wide, intended to fit inside a Space Shuttle's cargo bay (the propellant tank can be lofted into orbit on a big dumb booster, but a nuke requires the human supervision). The propellant tank is 31 meters long and 10 meters wide. The RNS is assumed to have an operational life of 10 Terra-Luna round trips (before the nuclear fuel rods were ). After that the RNS is attached to a chemical booster and tossed into a remote solar orbit. The NERVA has a 1360 kilogram shadow shield on top.
The shadow shield casts a 10 degree half-angle shadow, shielding was intended to reduce the radiation exposure to 10 REM per passenger and 3 REM per crew member per round trip to Luna and back. But in addtion to the shield it also relied upon propellant, structure, and distance to provide radiation shielding for the crew. Obviously as the propellant was expended, the shielding diminished. North American Rockwell Class 1 RNS with a stand pipe North American Rockwell tried to solve the problem with a 'stand-pipe', in which a cylindrical “central column” running the length of the main tank stood between the crew and the NERVA I engine. The central column would remain filled with hydrogen until the surrounding main tank was emptied. • McDonnell Douglas Class 1 Hybrid RNS. Note the secondary tank included in the propulsion module length.
Click for larger image McDonnell Douglas Astronautics Company dealth with the radiation problem by developing a “hybrid” RNS shielding design that included a small hydrogen tank between the bottom of the main tank and the top of the NERVA I engine. Space Shuttle in 'I' formation with RNS and giving it a re-fill.
Being careful to stay within the 10° safe area cast by the shadow shield. Even then only after the RNS engines have had 48 hours for the radioactivity to cool off. Osias, an analyst with Bellcomm, pointed out that the radiation dosage received by the astronauts riding the RNS was unacceptable.
Osias stated that the maximum allowable radiation dose for an astronaut from sources other than cosmic rays of between 10 and 25 REM per year (0.1 and 0.25 ). But the luckless astronaut on board the RNS would get 0.1 Sieverts every time the NERVA did a burn. Any external astronauts (not in the cone of safety cast by the shadow shield) at a range of 16 kilometers from a RNS operating at full power would suffer a radiation dose from 0.25 to 0.3 Sieverts per hour. Osias suggested that external astronauts not approach a burning RNS closer than 160 kilometers.
Which could be a problem if you are an astronaut in a lunar base when the RNS is burning to leave lunar orbit since the blasted thing orbits at an altitude of only 110 kilometers. If you are standing on the ground track of the RNS you'd better get into the radiation storm cellar. Nowadays the is set at 3 Sieverts, with a career limit of 4 Sieverts. Which means an astronaut piloting a RNS through 40 total burns would be permanently grounded by reaching his career limit of radiation. There are two mission types: the 8-burn mission and the 4-burn mission. 8-burn mission disadvantage: requires 4 extra burns for change-of-plane maneuvers.
This increases the required ΔV to 8,495 m/s, and reduces the payload size to 45,000 kg. Advantage: you do not have to wait for a launch window, you can launch anytime you want. 4-burn mission disadvantage: mission launch windows occur only at 54.6 day intervals. Advantage: since you are not required to perform change-of-plane maneuvers the required ΔV is reduced to 8,256 m/s and the payload size is increased to 58,000 kg. In both of these missions, it is assumed that the full payload is carried to Luna, where the payload is dropped off EXCEPT for the 9,000 kg that is the crew module. Presumably the crew wants something to live in for the trip back to Terra. RNS NERVA Engine Nuclear Shuttle Engine General Type Specific Impulse 825 sec Propellant Mass Flow 41.7 kg/s full power 0.3 kg/s aftercooling pulse Thrust 330,000 N Chamber temp 2,088°C Operating Life 10 hours (60 cycles) Engine Mass 12,577 kg including NDICE External Shadow Shield 4,000 kg Power req 28 vdc 2.3 KW normal 3.5 KW peak Gimbal Max Deflection ±3° Max Rate 0.25°/sec Max Accel 0.5°/sec 2 This is from McDonnell Douglas Nuclear Shuttle System Definitions Study, Phase III - Final Report - Volume II Concept and Feasibility Analysis - Part B Class 3 RNS - BOOK 2 System Definitions (1971).
This is for the Class 3 Reusable Nuclear Shuttle. It may or may not be the same engine as described above. Thanks to Erin Schmidt for bringing this report to my attention. The engine has a lifespan of 10 hours of total operation and 60 warm-thrust-chill cycles (I assume 10 hours at full thrust). After that it has to be disposed of, preferably into a distant solar orbit. The back of my envelope says this means roughly 10 Lunar missions before the engine is used up. The problem is that the reactor fuel elements are so.
By this time the engine has become so radioactive that it isn't worth the effort to try to extract the fuel elements for reprocessing. Which is a pity since only 15% of the nuclear fuel has been burnt. The NERVA has an internal radiation shadow shield, but that is a weak one just meant to protect the engine gimbals and thrust frame. To protect the crew there is an optional external shadow shield.
The ship designers do their best to use liquid hydrogen propellant as radiation protection insteaad of the external shield, since the blasted shield has a mass of four metric tons. NDICE is the NERVA Digital Instrumentation and Control Electronics. This allows the pilot to control the throttle, gimbal, and other functions. The part of NDICE that is actually mounted on the engine has a mass of 230 kg. The engine requires up to 3.5 kilowatts to operate the NDICE, the gimbal electric motors, the turbines, control valves, reactor control drums, and whatnot.
The gimbal pivots the engine for thrust vectoring, used to change the course of the spacecraft. The engine can be pointed up to three degrees off-center in any direction.
The maximum rate it can change the pivot is 0.25 degrees per second, but it takes time to get up to speed. It can only accelerate to maximum rate at 0.5 degrees per second per second. Lunar Ferry ΔV 15,000 m/s Specific Power? Thrust Power? Propulsion NTR-solid Specific Impulse 1000 s Exhaust Velocity 9,810 m/s Wet Mass M kg Dry Mass M/4.6 kg Mass Ratio 4.6 Mass Flow?
N Initial Acceleration? One really exciting nuclear rocket potiential lies in Earth-Moon transport. The Moon is 208,000 n mi from the Earth. The mission concept simply is one of ferrying back and forth between Earth and Moon terminal orbits. We can think of the ferry terminals as 300 n mi Earth orbits and 100 n mi lunar orbits. The essence of the lunar ferry concept is presented in Figure 11-8 (the one with the Earth-Moon orbits). The lunar vehicle would do all the propulsive legwork in the the terminal orbits and between the terminal orbits.
Chemical systems would be employed as shuttle vehicles at the Earth terminius and at the lunar terminus. This would permit specialization in chemical systems where they are most capable: planetary launch and entry. The nuclear ferry would have one rocket reactor with capability for multiple reuses, in-orbit replenishment, multiple restarts, and full nozzle maneuverability. We would expect the reactor to have a proven I sp on the order of 1000 seconds.
It would have proven reliability, man-rating, pilot control, and long life. We would not expect the ultimate in solid-fueled reactor technology but we should be headed in that direction. Note in Figure 11-8 that the ferry trajectory is in the form of a 'figure-8.' This is because it is necessary to transfer from one gravitational force center to another. Each section of the figure-8 can be thought of as an elliptical orbit: one focus at Earth and one focus at the Moon.
The two ellipses 'join' each other at a transfer region which is about 85% of the distance from Earth (the crossover occurs at about 180,000 n mi from Earth or about 28,000 n mi from the Moon). When going from Earth to Moon, the transfer point is called translunar injection.
When going from the Moon to Earth, the transfer is called transearth injection. The injection maneuvers actually start well in advance of the trajectory crossover. Caution is required when interpreting Figure 11-8. It gives the impression that the launching/entry trajectories, the rendezvous/docking orbits, and translunar/transearth ellipses are all in the same orbit plane with each other.
This is not the case. We are dealing with noncoplanar orbit trajectories. Furthermore, they are variable noncoplanar trajectories which change from day to day and from month to month. As a consequence, the target plane — that plane connecting the Earth and Moon centers — 'corkscrews' around the major axis of the figure-8 flight path. The corkscrewing of the ferry trajectory introduces fluctuations in the ΔV requirements. Table 11-4 Nuclear Ferry ΔV Requirements Maneuver Feet per second Earth Orbit Docking 1,750 Earth-Space Plane Changes 3,500 Earth to Translunar Injection 10,000 Translunar to Lunar Orbit 3,500 Lunar-Space Plane Changes 1,500 Lunar Orbit Docking 750 Lunar to Transearth Injection 3,500 Transearth to Earth Orbit 10,000 Midcourse Corrections 500 Abort Reserve 5,000 Total ΔV 40,000 A representative summary of the round trip ΔV requirements is given in Table 11-4. This listing includes all contingencies (a lunar mission can be performed with less ΔV than table 11-4 but the risk-potential increases).
Note that total ΔV is 40,000 feet per second (fps). A single stage nuclear vehicle with an I sp of 1000 sec would have a ΔV capability of nearly 50,000 fps. Hence, there is some excess ΔV available.
The unused nuclear ΔV can be applied to reducing the trip time. The normal one-way trip time for a chemical propulsion system is about 60 hours (2 ½ days). Because chemical lunar missions border on marginal ΔV capabilities, the chemical trip time cannot be reduced much below 60 hours. In the case of nuclear systems, for an additional expenditure of 3,000 fps, the one-way trip time can be reduced to 20 hours. The effect of other ΔV expenditures on trip time is shown in Figure 11-9 (not shown), It can be seen that if an attempt is made to reduce the trip time below 20 hours, the extra ΔV requirements are disproportionate to the time gained. Therefore, a value of 20 hours will be selected as the nuclear ferry time base.
If the lunar terminal orbit is 100 n mi altitude, the orbit period is about 2 hours. If the lunar terminal activities necessitate as much as two orbit periods fur completion, the nuclear ferry turnaround could be made within 24 hours of Earth departure. If two nuclear ferry vehicles were used, we could have daily service to the moon and back! All-chemical lunar rocket systems could not possibly compete with this schedule. The advantages of reduced lunar trip time are self-evident There is reduced time of confinement of astronaut, scientific, and technical personnel to the limited quarters of spacecraft. In-transit boredom and monotony are reduced. Less life support equipment is required: less oxygen, less food, less waste disposal.
There is less exposure to weightlessness and less exposure to space radiation. The less the life protection equipment required, the more transport capacity for lunar basing supplies. In the lunar terminal orbit, all exchange activities would take place at the pilot end of the nuclear ferry.
This is because the propulsion reactor would be kept idling. The major features involved are presented in Figure 11-10 (middle image above). One feature not always self-evident is the need to off-load chemical propellants from the nuclear ferry to the lunar shuttle. To make the propellaut transfer, special cargo tanks on the nuclear ferry and special piping on the chemical shuttle would be required, It is assumed that chemical propellants for the shuttle vehicle probably could not be manufactured on the Moon and therefore would have to be transported from Earth. RM-1 Propulsion chemical ΔV (estimated) 2,800 m/s Specific Impulse (estimated) 314 s Length 23 m Max Width 7.4 m Crew 4 This design was the result of a nice bit of collaboration between Walt Disney and (architect of the Saturn V). Disney's TV show 'The Wonderful World of Color' had decades of material for the segments Fantasyland, Frontierland, and Adventureland, but zero for Tomorrowland. Disney's concept executive Ward Kimball had been following Collier magazine's awe inspiring series, detailing von Braun's plans for manned spaceflight.
This series would be perfect for a set of Tomorrowland episodes. Kimball quickly discovered that he was in over his head, but Disney allowed him to hire technical experts. Kimball proceeded to enlist the main tech experts from the Collier's series: Willey Ley, Heinz Haber, and of course Wernher von Braun. Kimball realized that when it got down to the fine details, you'd have to get help from The Man himself. When Kimball made a tentative inquiry to von Braun, the latter jumped in with both feet. Von Braun desperately needed favorable publicity for his Moon mission. The Colliers article reached barely three million viewers.
A Disney show could reach tens of millions! The three Tomorrowland episodes were,, and. The middle episode is where the RM-1 makes its appearance. The RM-1's mission was a simple loop around Luna, with no landing (the same as the ).
The only things you needed was a few days of life-support for the crew, and about 2,700 m/s of delta V. And a bit under 100 m/s to brake back into Terra's orbit. So the spacecraft can be built out of bits and pieces of the existing and rockets. The front part of the RM-1 was the top stage of the passenger ferry minus the wings but including the passenger section, life support, and engine. Six standard propellant tanks were attached to increase the delta V to 2,800 m/s. When the extra tanks were empty, they were retained as protection from meteors (unnecessarily, meteors are not that common), but jettisoned just before the braking burn into Terra orbit to reduce the ship's mass. On a nose spike was attached a nuclear reactor, for on-board power.
A conical protects the crew from reactor radiation. The reactor is ludicrously tiny, in reality it would be quite a bit bigger. And the spike would be a bit as well. A dish antenna for radar and communication is on a set of tracks around the ship's waist.
Unfortunately the propellant tanks block the view aft. It also has a belly docking port for a, the port is already standard on the passenger ferry. The deep space ship above (click on the image for full sized view) was inspired by the in the previous post, and modeled in the wonderfully simple and handy. The shuttle alongside is a rough approximation of the NASA shuttle, and thus a thorough anacronism in this image, but provided as a scale reference. Of course you want some specifications of the ship. Even if you don't, you get them anyway: Length Overall 300 meters Departure Mass 10,000 tons Propellant Load H 2 5000 tons Drive Mass 2000 tons Keel and Tankage 1000 tons Gross Payload 2000 tons Flyway Cost $5 billion (equivalent) The payload includes a hab with berthing space for 50-200 passengers and crew, depending on mission duration, and a pair of detachable pods for 500 tons of express cargo, plus service bays and the like.
What this ship can do depends on its drive engine performance. If the drive puts out 2 gigawatts of thrust power — my baseline for a Realistic [TM] nuke electric drive — the ship can reach Mars in three months, give or take. (The sim gave 92 days for a 0.8 AU trip in flat space.) With a later generation drive putting out 20 gigawatts it can reach Mars in a little over a month, or Saturn in eight months.
The general arrangement of this ship is driven by design consideration — a nuclear drive that needs to be a long way from the crew, with large radiators to shed its waste heat; tanks for bulky liquid hydrogen; and a spinning hab section. Most serious proposals for deep space craft in the last 50 years have had more or less this arrangement —, because in those days the audience would have been puzzled that a deep space ship had 'wings.' A large, long-mission military craft, such as a, might not look much different overall — replace the cargo pods with a laser installation and side-mounted main mirror, and perhaps a couple of smaller mirrors on rotating 'turret' mounts. Discussions here have persuaded me that heavy armor is of little use against the most likely threats facing such a ship. Within these broad constraints, however, spaceships offer a great deal of design freedom, more than most terrestrial vehicles. Ships, planes, and faster land vehicles are all governed by fluid dynamics, and even movable shipyard cranes must conform to a 1-g gravity field.
A spaceship, unless built for aerobraking, will never encounter fluid flow, and the forces exerted by high specific impulse drives — even torch level drives — are relatively gentle. This ship might have had two propellant tanks, or half a dozen, instead of four. And the entire industrial assemblage of tanks and girders might be concealed, partly or entirely, within a 'hull' of sheeting no thicker than foil, protecting tanks and equipment from shifting heat exposure due to sunlight and shadow. Much of the ISS keel girder has a covering of some sort — in close-ups it looks a lot like canvas — that in more distant views gives the impression of a solid structure. In fact the visual image of the ISS is dominated by its solar wings and radiators. The hab structure is fairly inconspicuous by comparison, like the hull of a sailing ship under full sail.
This would be true to an extreme of; a 1-gigawatt solar electric drive would need a few square kilometers of solar wings. Even nuclear drives, fission or fusion, require extensive radiators — probably more than I showed — with other ship systems needing their own radiators, at varied operating temperatures. Unless the ship has an onboard reactor it must also have solar collectors for use when the drive is shut down.
All of which may do more to catch the eye than heavier but smaller structures such as the hab or even propellant tankage. And then there is color: the gold foil of the main ISS solar wings, for example. Hollywood knows nothing of this (though I'm surprised they haven't picked up on the gold foil). Hollywood is no more interested in what real spaceships look like than it is in how they maneuver. This is only natural, even though we hard SF geeks complain. Hollywood doesn't care because its audience has almost no clue of what spaceships look like, or act like, getting most of their impressions from Hollywood itself.
The one actual spacecraft to have iconic visual status, the Shuttle, essentially looks like an airplane. The ISS has not yet acquired iconic status, though it may, especially after the Shuttle is retired. And perhaps it looks so unlike terrestrial vehicles that our eye does not yet know quite what to make of it. As a point of comparison, watch aviation scenes in old movies, especially from before World War II. You'll see airplanes whooshing past (sometimes in pretty unconvincing special effects shots), but you will rarely see what is now a standard shot — a plane filmed from another plane in formation, hanging 'motionless' on the screen, clouds and distant landscape rolling slowly past, until perhaps the plane banks and turns away. It is a standard shot because it is so very effective.
But older movies rarely used it, because audiences would have had no idea what they were seeing. Everyone knew that airplanes were fast, and had at least some idea that their speed is what kept them in the air. A plane apparently hanging in midair would make no sense. What changed all this, I would guess, is World War II. A flood of newsreel footage included many formation shots, and audiences gradually absorbed a feeling for what midair footage really looks like. When a postwar Jimmy Stewart enlisted for (1955), Hollywood — and its audience — were ready to see the B-36 and B-47 showcased in all their glory, including airborne formation shots.
I know what you bloodthirsty people are thinking — one good space war, and everyone will grok the visual language of space travel. Shame on you. Given enough civil space development, and time, people will get the hang of it. The beauty of spaceships is in the eye of the beholder. The familiar aesthetics of terrestrial vehicles are as irrelevant to them as to Gothic cathedrals (which in some broad philosophical sense are themselves spaceships of a sort). General principles of design will provide some guidance.
Even in making the quick thrown-together model above I found that slight changes in proportion could make the difference between a jumble of parts and a unity. But the real visual impact of spaceships is something we will only learn from experience, by the glint of a distant sun. Download Vidio Naruto Shippuden Episode 310. • Orbital Patrol Ship Artwork by Rick Robinson Orbital Patrol Ship Stats Propulsion Chemical H 2-O 2 Exhaust Velocity 4,400 m/s Specific Impulse 449 s Thrust 3.5×10 6 N Thrust Power 7.7 gigawatts Total ΔV 6,100 m/s Mass Budget Engine Mass 7 mton Heat Shield Mass 15 mton (15% re-entry mass) Terra Recovery parachute, retro, landing gear 5 mton (5% landing mass) NonTerra Recov landing legs Luna, Mars 5 mton (5% landing mass) Misc attitude jets, electrical, etc. 20 mton (20% dry mass) Aerodynamics controls, farings, etc. 5 mton (5% dry m) Tankage body 18 mton (6% of 300 mton H 2-O 2) INERT MASS 75 mton Payload, hab module cargo bays 25 mton DRY MASS 100 mton Propellant H 2-O 2 300 mton WET MASS 400 mton Mass Ratio 4.0 Plus booster rocket? Mton This is a splendid spacecraft designed by Rick Robinson, on his must-read blog.
This was designed for his Orbital Patrol service, which he covered in. The important insight he noted was that if you can somehow get your spacecraft into orbit with a full load of fuel/propellant, it turns out that most cis-Lunar and Mars missions. So you make a small chemical rocket and lob it into orbit with a (heavy lift launch stack).
This will be the standard Orbit Patrol ship. It can also be boosted into orbit by a smaller booster rocket, then using the patrol ship's engines for the second stage. So as not to cut into the ship's mission delta V, it will need access to an to refuel. At a rough guess, you'll need 9,700 m/s delta V to boost the patrol ship into orbit (7,900 m/s orbital velocity plus gravity and aerodynamic drag losses). So the booster will need 9,700 m/s with a payload of 400 metric tons.
Bonus points if the booster is reusable. Actually, it reminds me a bit of the old. At a rough guess, Rick figures that if the ship is capsule shaped it will be about 12 meters high by 14 meters in diameter. If it is wedge shaped, it will be about 40 meters high by 25 meters wide by 8 meters deep.
In both cases, total interior volume of 1,200 m 3 (of which 900 m 3 is propellant), and a surface area of 800 m 2 Present day expandable propellant tanks have a mass of about 6% of the mass of the liquid propellant. Rick is assuming that in the future the 6% figure will apply to reusable tanks as well. If my slide rule is not lying to me, the 300 metric tons of H 2-O 2 fuel/propellant represents 33.3 metric tons of liquid hydrogen and 266.7 metric tons of liquid oxygen. About 470 m 3 of liquid hydrogen volume (sphere with radius of 4.8 m) and 234 m 3 of liquid oxygen volume (sphere with radius of 3.8 m).
This is a total volume of 704 m 3 which falls short of Rick's estimate of 900 m 3 so I probably made a mistake somewhere. Landing on Terra will use retro-rockets, the heat shield for aerocapture, maybe a parachute, and aircraft style landing gear for belly landing.
Landing on Luna or Mars will be by tail-landing on rear mounted landing legs. That will also mean reserving some of the propellant for landing purposes. Note that the heat shield is rated for the ship's unfueled mass (heat shield mass = 15% of ship's re-entry mass), there is not enough to brake the ship if it has propellant left. This assumes a 'low-high'low' mission profile: start at LEO, go outward to perform mission while burning most of the propellant, then return to LEO or even land on Terra. So 15 metric tons for heat shield is for a ship with a mass of 100 metric tons at re-entry (ship's total dry mass). If the ship is going to aerobrake then return to higher orbit, it will need more heat shield mass to handle the extra mass of get-home propellant. This will savagely cut into the payload mass, which is only 25 metric tons at best.
For example, if the mission had the ship heading for translunar space from LEO after aerobraking, the extra propellant mass at aerobrake time will increase the heat shield mass from 15 metric tons to 31. This will reduce the payload from 25 metric tons to 8.
But by the same token a ship that will not perform any aerobraking can omit the heat shield entirely, using the extra 15 metric tons for more propellant or payload. Payload includes habitat module (if any) as well as cargo, since hab modules are optional for short missions. The gross payload is 25 metric tons, of which 20 is cargo and the other 5 mtons are payload bay structure and fittings. If you assume two tons of life support consumables per crew per two week mission; then the ship could carry a crew of five plus 12 mtons of removable payload, or a crew of 10 and 4 mtons of payload (the more that payload is consumables, the less mass needed for payload bay structure). Payload Crew 25 Hab Module 100 tons Consumables 25 tons Other Payload 75 tons Total Payload 200 tons Propulsion Bus Engine+Radiator 200 tons Tankages+Keel 100 tons Stats Dry Mass 475 tons Loaded Mass 500 tons Propellant Mass 500 tons Wet Mass 1000 tons The discussion thread about ' veered, among other things, into a discussion of patrol missions in space.
My first reaction was that (so long as you aren't dealing with an interstellar setting) there is no place in space for wartime patrol missions. But the matter might be more complicated, and for story purposes probably should be.
According to The Free Dictionary, patrol is The act of moving about an area especially by an authorized and trained person or group, for purposes of observation, inspection, or security. This fits my own sense of the word, and is in fact a bit broader, 'security' including SSBN patrols, which are not observing or inspecting anything, just waiting for a launch order if it comes.
In a reductionist way you could say that all military spacecraft are on patrol, since they are all on orbit, and if they are orbiting a planet they have a very regular 'patrol area.' But this is not what most of us have in mind. We picture a patrol making a sweep through an area, looking for anything unusual, ready to engage any enemy they encounter, or report it and shadow it if they cannot engage it. Back in the rocketpunk era it was plausible that, say, Earth might send a patrol past Ceres to see if the Martians had established a secret base there.
But (alas!) telescopes 'patrolling' from Earth orbit can easily observe the large scale logistics traffic involved in establishing a base; watch it depart Mars and track it to Ceres. If you want a closer look you can send a robotic spy probe. If you engage in 'reconnaissance in force' by attacking Ceres, that is a task force, not a patrol. In an all out interplanetary war there may be plenty of uncertainty on both sides, but very little of it can be resolved by sending out patrols.
But of course all-out war is not the context in which the Space Patrol became familiar. I associate it with; apparently the 1950s TV series had an independent origin (unlike, who was Heinlein's unacknowledged literary child). The rocketpunk-era Patrol, which in turn gave us Starfleet, was placed in the distinctly midcentury future setting of a Federation. This is as as monorails. But plausible patrolling is not confined to Federation settings.
It can justified in practically any situation but all out war. Orbital patrol in Earth orbital space will surely be the first space patrol, and could be imagined in this century. It might initially be a general emergency response force, because travel times in Earth orbital space are short enough for classical rescue missions. On the interplanetary scale, with travel times of weeks or more likely months, rescue is rarely possible. But eventually power players will want some kind of police presence or flag showing in deep space. As so often in these discussions, I picture a complex and ambiguous environment in which policing, diplomacy, and sometimes low level conflict blur together.
To take again our Earth-Mars-Ceres example, there are kinds of reconnaissance that cannot be carried out by robots (short of high level AIs). If Ceres closes its airlocks to liberty parties from a visiting Earth patrol ship, that conveys some important intelligence information. The ships that perform these missions will be fairly large (and expensive). They must carry a hab pod providing prolonged life support for a significant crew: at least a commander and staff, SWAT team of, and some support for both. Let us say a crew of 25—which is cutting the human presence very fine.
Now we can venture a mass estimate. Allow 100 tons for the hab compartment plus 25 tons for crew and stores plus 75 tons other payload, for a total payload of 200 tons. Let the drive bus be 200 tons for the drive, including radiators, and 100 tons for tankage, keel, and sundry equipment. Our patrol ship with a crew of 25 thus has a dry mass of 475 tons, mass fully equipped 500 tons, plus 500 tons propellant for a full load departure mass of 1000 tons. Cost by my usual rule of thumb is equivalent to $500 million, perhaps $1 billion after milspecking, expensive compared to military planes, cheaper than major naval combatants.
This is no small ship. If the propellant is liquid hydrogen the tanks have a volume of about 7000 cubic meters, equivalent to a 7000 ton submarine. The payload section is about two thirds the mass of the ISS and of roughly comparable size, though the hab is probably spun giving the prolonged missions. Armament is necessarily modest. The 75 tons of additional payload allowance probably must include a ferry craft for the espatiers and an escort gunship or two, plus their service pod, leaving perhaps 15-20 tons each for kinetics and a laser installation.
The laser might be good for 20 megawatts beam power, with plug power from the 200 megawatt drive engine. This ship is no, but the laser is respectable. Assuming a modest 5 meter main mirror and a near IR wavelength of 1000 nanometers, at a range of 1000 km it can burn through Super Nano Carbon Stuff at rather more than 1 centimeter of per second. Its armament is also rather 'balanced.' My model shows that this laser can just defeat a wave of about 1000 target seekers, each with a mass of 20 kg, closing at 10 km/s—thus a total mass of 20 tons, comparable to its kinetics payload allowance. Deploying troops, or personnel in general, is impressively expensive: About three fourths of the payload and cost of a billion dollar ship goes to support and equip a crew of 25, with perhaps a dozen espatiers.
For comparison the (LHD-8) displaces 41,000 tons full load, carries a crew of 1200 plus 1700 Marines, and costs about $1.8. So by my model it costs about as much to deploy one espatier as 80 marines. And this ship is about the minimum patrol package, so standing interplanetary patrol is a costly and somewhat granular business, something not everyone can afford. Ray McVay Rocketpunk Patrol Ship Dry Mass 76.2 metric tons Wet Mass 384.6 metric tons Mass Ratio 5 Length Z 73 meters Length Y 20.1 meters Length X 15.2 meters Engine x2 F-26-A LH/LOX Thrust 7.7×10 6 N Acceleration 0.5 g ΔV 8,200 m/s This is the same one from the other day, only dressed up with a nice logo and some stats. These are realistic capabilities made courtesy of the charts and other information available from Atomic Rocket and inspiration from Rick Robinson's Rocketpunk Manifesto. My PL differs from the one in Rick Robinson's article in a few key areas. The main difference is that it is not made for long hauls.
It only has a delta v of about 8200 m/s. This will not get one far in the solar system but it allows a forward deployed Patrol Craft a sufficient 'range' to perform many of the missions we discussed in the on. Our little A-Class has enough Delta V to shape a light-second orbit around a convoy in deep space, conduct missions anywhere in cis-lunar space, or to reach any moon of Saturn from any other moon. Obviously, this rocket is mostly propellant (mass ratio 5). If you drew lines through the side view of the rocket that bracket the docking rings, you would encompass the entire pressurized volume. I've got to say, it's nice to work on a warship for a change — I don't have to make it economical to run!
One of the interesting things about this design is actually the freedom the little carried craft gives me. It was a throw-away touch, originally — a design borrowed from But as I got to looking at the little thing, I realized that it's about the size of the Saturn V stage/Apollo/LM stack. That means it should be able to go from Earth Departure to Lunar orbit.
That means that it has the Delta V to ferry crew to and from a Patrol Craft on station away from the convoy. That means, like submarines, our Patrol Craft can have two crews and stay out for a lot longer than otherwise. This is one of those realistic touches that I hope add to the charm of the rocket's design.
Ed note: a 1500 nanometer near infrared laser with a 10 meter fixed mirror can a 4 centimeter spot size out to 220 kilometers or so. A 4 meter mirror can have a 4 centimeter spot size out to 87 kilometers or so.
Solar-electric engines, according to Isaac Kuo at sfconsim-l, may soon achieve a power output density of about 400 watts per kilogram, when operating near Earth distance from the Sun. If you do not see what this sort of technical information could possibly have to do with so lovely an image as gossamer wings, you probably reached this blog by accident, have no poetry in you, or both. What makes it potentially relevant as well as beautiful is that 400 watts/kg is in hailing distance of the 1 kW/kg that Isaac and I independently chose as a benchmark for nuclear-electric drive, and generally as needed for relatively fast interplanetary travel. A spacecraft using solar electric drive can thus reach the same interplanetary speeds as its cousin, though it will take somewhat longer to reach cruising speed, and somewhat longer to slow down. It is a fair prospect that with a few decades' further progress, by the time we're actually building interplanetary ships the performance of the two drives will be comparable. This is a big deal, because solar-electric space drive is technically and operationally elegant, while nuclear-anything drive, and especially nuclear-electric drive, is not.
A solar electric drive has almost no moving parts. A nuclear-electric drive has lots of complex internal plumbing to draw energy from the reactor and incidentally keep it from melting. This plumbing operates under very nasty conditions, radioactivity being nothing to sheer high temperatures. Plumbing is a big part of what makes spaceships so expensive, because it is complicated, full of parts that can jam, and as there is never a plumber around when you need one, it has to work perfectly for months at a time.
(Even if you have a plumber in the crew, taking a nuclear reactor apart en route is a pain.) Robinson's Second Law: For each gram of physics in futuristic space tech, expect about a ton of plumbing. Nuclear drives are also full of nasty fissionable stuff, tricky and dangerous to work with, requiring heavy shielding to get anywhere near (and radiation goes a long ways in space), requiring extreme security measures in handling and storage, and socially uncomfortable no matter how careful your procedures are. In short, anything that gets rid of nuclear reactors in space is a huge plus on every level of operation, from spacecraft construction and maintenance to obtaining funding.
Solar electric drive with comparable performance banishes nuclear reactors from the inner Solar System. You don't need them for travel, and you certainly don't need them for anything else, because one thing the inner Solar System has an ample and endless supply of is sunshine. Those skies are never cloudy all day.
Solar electric power does gasp for air, or for sunshine, as you move outward from the Sun. At Mars, thrust is about half as much as near Earth. In the asteroid belt it is about a fifth to a tenth, at Jupiter one twenty-fifth, at Saturn one percent. To give this some context, a one-milligee drive, baseline performance near Earth, nudges a ship along at about 1 km/s per day, reaching orbital transfer speeds in a week or two. At Jupiter, the drive delivers some 40 microgees, and a ship puts on about 1 km/s per month, thus the better part of a year for orbital transfer burns. The time lost due to sluggish acceleration is only half as much, some six months, and a Jupiter mission would likely be upwards of a year each way even for a nuke-electric ship.
So until we have regular bus service to Jupiter, the time cost is not dreadful. The inner Solar System, through the asteroid belt, can be efficiently traveled by solar-electric drive, which ought to hold us through this century and into the next. Of course nuclear-electric ships can be built, but Isaac also pointed out a subtle effect that could sideline them.
Over the decades to come we will build solar-electric probes, and later ships, steadily developing the technology, while nuke-electric remains a paper tech, falling further and further behind. A serious advance into the outer system will require a faster drive in any case—by that time perhaps a fusion drive, which can still be two orders of magnitude below the magical performance level of a 'torch.' Let's mentally sketch-design a solar electric ship.
Departure mass with full propellant load is 400 tons, broken down as follows: • Payload, 100 tons • Structures and fitting, 50 tons • Drive engine, 100 tons • Propellant, 150 tons The drive engine we make an advanced one, meeting the baseline standard of 1 kW/kg. Thus rated drive power is 100 megawatts. If the exhaust velocity is 50 km/s (specific impulse ~5000 seconds), 80 grams of propellant is shot out the back each second.
Thrust is 4000 Newtons, about 1000 lbs, giving our ship the intended 1 milligee acceleration at full load. Mass ratio is 1.6, so total ship delta v available on departure is 23.5 km/s, enough for a pretty fast orbit to Mars. We could 'overload' this ship with a much bigger payload, another 400 tons (thus 500 tons total payload). Max acceleration falls to half a milligee, and mission delta v to 10 km/s—still ample for the Hohmann trip to Mars, for slow freight service. Since we want to go there ourselves, we will stick with the faster version and configure it as a passenger ship. Each passenger/crewmember requires cabin space, fittings, life support equipment, provisions and supplies for the trip, plus the mass of the passenger and baggage—in all, say, about 3 tons per person, so our ship carries some 30-35 passengers and crew.
The cabin structure of this ship might be about the size of a 747 fuselage, divided into berthing compartments or roomettes, diner/lounge area, galley, storage spaces, and life support plant. If the propellant is hydrogen, the tankage will be about the same size; if other stuff is used, the tankage will be smaller. All in all, the hull portion of our ship is comparable in size and mass to a jumbo jet. As space liners go this is a modest-sized one, as its modest passenger/crew capacity shows. Now, finally, the gossamer wings part. We accounted for the mass of the drive engine, including solar collectors, but have not yet looked at the physical size of the solar panals. They are big.
If we assume that about 35 percent of the sunlight that hits them is converted into thrust power, they capture some 500 watts per square meter at 1 AU—meaning that for a 100 megawatt drive you need 200,000 square meters of solar panels, a fifth of a square kilometer. This trim little interplanetary liner is physically enormous, or at least its solar wings are. The 'wingspan' might well be one kilometer, 'wing chord' then being 200 meters.
In sheer size our ship is much bigger than any vehicle ever built (though freight trains can be up to about 2 km long). Angular, squared-off, an instrument of technology—but how can this ship be anything but a thing of beauty, an immense gleaming-black butterfly? If that is too fluttery, say a dragonfly, or to be prosaic an equally immense gleaming-black kite.