9.2 TIPS FOR INEXPERIENCED ROCKET CADETS 9.0 BACKGROUND “What do I do first?” You need to research a card (thruster or 9.1 DESIGNER’S NOTES robonaut) with a low fuel consumption. A “1” is great, a “4” The original concept for this game was a “Lords of the Sierra Madre” in is marginal. The PRC player*** can consider an dash to space. With mines, ranches, smelters, and rail lines all purchased and claim Hellas Basin on Mars, using just his crew card. He controlled by different players, who have to negotiate between them- needs 19 fuel steps (6 WT) along the red route to do this. selves to expand. But space does not work this way. “What does my rocket need?” Your rocket needs 4 things: Suppose you have a smelter on one main-belt asteroid, powered by a • A card with a thruster triangle (2.4D) to act as a thruster. • A card with an ISRU rating, if its mission is to prospect. beam-station on another asteroid, and you discover platinum on a third • A refinery, if its mission is to build a factory. nearby asteroid. Unfortunately for long-term operations, next year these • Enough fuel to get to the destination. asteroids will be separated by 2 to 6 AUs.* Furthermore, main belt Decide between a small rocket able to make multiple claims, Hohmann transfers are about 2 years long, with optimal transfer opportu- or a big rocket including a refinery and robonaut able to nities about 7 years apart. Jerry Pournelle in his book “A Step Farther industrialize the first successful claim. The big rocket will be Out” argues that a “belter civilization” is impossible for these reasons. more expensive to boost and to fuel. From a given asteroid, it’s easier to get to and from Earth than from another asteroid (unless the asteroids are in the same Hirayama family). “I need funds!” Researching a card and selling on the Free So, the game design had to make travel between asteroids take a long Market is almost always superior to the Income Operation. time, but not cost so much fuel (low delta-v). “OK, I have a rocket boosted, where do I go to prospect?” Space travel is extraordinarily inefficient compared to surface travel. Both Look at unclaimed sites for their hydration (your ISRU must fuel and propellant are conspicuously missing in all that emptiness. Every be at least equal to land) and size (your prospecting roll bit of mass is valuable in space. Water and dirt, both dirt-cheap on Earth, must be equal to or less for success). These are the most become expensive propellants out there. In order to husband the important rules in the game. valuable supply of propellant, it has to be expelled as fast as possible. “OK, how do I get there, and how much fuel?” The tapestry of Kinetic energy scales as the velocity squared, so all the energy squan- space is extraordinarily complex. The daunting labyrinthine dered making the propellant move fast leaves little to move your rocket. map is designed around the “interplanetary transport This is why rockets are power hogs, each needing 10X or a 100X more network” (Hohmann spirals distorted by Lagrange gravita- energy than a factory. An electric rocket in this game consumes 60 MWe tional points). Beginners should follow signpost routes, to develop barely enough thrust to lift me off the ground on Earth. And and stop at each Hohmann intersection where a turn is thus, this game centers on rocket design more than factory location. necessary. Bring steps of fuel equal to your fuel consump- Because LEO is drier than the driest desert, there is money to be made by tion times the number of burns to your destination. Unless importing water from nearby worlds. The closest hydrated body to LEO, making an aerobrake or direct landing, don’t forget to bring speaking in delta-v terms, is the moonlet Deimos (closer than the Earth, lander fuel equal to the site’s size. Or better yet, bring a 9•6 closer than Luna.) Google “The Deimos Water Company” by David Kuck thruster (like missile crews). Switching to this during the of Oracle, Arizona for details. turn of touchdown saves lander fuel. Imagine MET tugs working an asteroid mine 10 km/sec from LEO. Every “OK, what is a lander?” Interplanetary spaceships, with their gram of ore returned will need 2.718 grams of water propellant to move it unwieldy radiators and low thrust engines, seldom land on to LEO.** Therefore, every nugget of material moved must be refined as a world. It is assumed they carry a chemical lander for that. pure as possible before freighting it, and there must be a source of water Thus, lander fuel is independent of your engine, unless you at the site. And the rocket transport itself must be as light as possible. have a modified thrust greater than the site size. If so, you Rockets with gossamer radiators and spidery trusses will glide with a can land or lift off directly for no fuel. However, the larger majesty that recalls the featherweight bulk of Zeppelins. worlds are surrounded by burns that cost fuel to escape: 1 burn for Luna, 2 for Mars and Mercury, and 4 for Venus. The High Frontier is a frontier of mysteries. Why are there no worlds of size 7 or 8? Why do the largest Trojans have the most tilted orbits? Why does “OK, I prospected. What refinery do I need to build a factory?” Hyperion rotate chaotically? Nobody knows. Phil Eklund, 2010. Any refinery can be used to build any factory. However, if you are using a factory to build new refineries, the refinery *1 AU is the average Sol-Earth distance. ***NASA and ESA players can do this as well, but risk **Calculated using the rocket equation, see the footer being claim jumped by the PRC if he is in the game. built must have a product letter matching the site spectra. on page 1. 2.718 is Euler’s number. This is the most commonly confused rule of the game.

Beam-Energy – An electric rocket has a high fuel Manufactories vs. Nanofactories – The ancient Aerostat Gondola Factories – A factory floating economy but suffers from a low acceleration if it manufacturing style of engineering handles atoms and in an atmosphere can liquefy valuable gases for carries its massive powerplant and generator around. molecules in bulk. This has produced everything from propellants and fusion fuels. For instance, a If it receives its energy from a laser beam instead, it is flint chips to computer chips. The new zero-gee hydrogen-balloon factory floating just beneath the much faster. Such a beamed-power system would nanofacturing engineering handles individual atoms clouds on Venus extracts hydrogen, carbon, need: (a) the high efficiency production of megawatt and molecules. It constructs objects using sequences oxygen, nitrogen, sulfur, and possibly phospho- laser beams, (b) adaptive optics with handshake of chemical reactions directed by nonbiological rous from the “air de Venus”. Contrasted with the feedback over light-minutes of range, (c) a receiving molecular machinery. The fullerene C60 nanotubes, hellish surface, temperatures and pressures at Fresnel lens (actually a series of thin lenses, as a nicknamed “Buckytubes”, will be the most important such altitudes (50 km) are about Earth normal. normal lens would be far too heavy), and finally (d) a nanofacturing product. The space production of Humans working outside the gondola won’t need blackbody cavity or photovoltaics to convert the beam carbon nanotubes doesn’t introduce catalyst impurities space suits, only an oxygen tank and protection energy into useful electricity or thrust. High Frontier and isn’t restricted on length, as it is on Earth. from the acid rain. On Saturn, a hot air balloon assumes a 60 MW beam; currently only gas lasers Depending on their structure, diameter, and chirality, some 212 meters across would extract the rare provide such powers. The output wavelength for a nanotubes with diameters in the nanometer range have isotope Helium 3 for use in clean fusion reactors CO2 laser is 10.6 µm (infrared), which is not great either metallic or semiconducting properties. Kevlar- back on Earth. Liquefaction of 2200 ton/yr of because the longer the wavelength, the wider the coated nanotube composites and nanotube-reinforced 3He-D fusion fuel, plus 4800 ton/yr of H2 beam spread due to diffraction and the less energy plastics exhibit ultrahigh tensile strength and stiffness. propellant, requires 10 MWe, plus another 400 carried per photon. What is needed is a solid state or Nanotubes can form the backbone structures of MWe for separation processes. These sites are disk laser with blue or green light output, however so molecular machinery, or can be used as fine flexible windy (350 kph on Venus, 1440 kph on Saturn), far solid media cannot withstand the high fluences for fibers woven to fifty times the strength of an equivalent and deep in the gravity well. The escape delta-v is a continuous cw or pulsed run. mass of aluminum. Courtesy K. Eric Drexler 10 km/sec on Venus and 15 km/sec on Saturn. Personal communication, Dr.Andrew V. Pakhomov and Dr. Leik Myrabo. 12 Courtesy Peter Kokh, “Moon Miners Manifesto”, 2009. 9.3 GAME SCALE 9.4 PATENT DESCRIPTIONS The technology of High Frontier is real. • Each turn is one Earth year. Note: Temperatures are listed in degrees Kelvin (K), (where 0 K is absolute zero, and water boils at 372 • Each Crew card is an eight-man crew with life support. K). To convert degrees K into degrees C, subtract 272. Plasma temperatures are listed in kilo-electron volts (keV). To convert keV into degrees K, multiply by 11604000. See crew glossary entry. compound parabolic • Each mass point is a quadecaton (40-tonnes, or 40,000 kg). Ablative laser robonaut – A rocket can be driven by high-energy, short-duration mirror • Fuel consumption is inversely proportional to a rocket’s (<10-10 sec) laser pulses, focused on a solid propellant. A double-pulse system specific impulse in seconds as follows: is used: the first pulse ablates material and the second further heats the ablated gas. A low Z propellant, such as graphite, obtains the best specific impulse game fuel vacuum specific propellant exit (4 ksec). Unfortunately, ice is not a suitable medium due to melting and “dribbling” consumption impulse velocity (Ve) losses. Primary and secondary mirrors focus the pulses at irradiances of 3 ! 1013 460 sec 4.6 km/sec W/cm2. The mass-removal rate is 3 µg per laser pulse. Powered with a 60 MW beam, an ablative laser thruster has a thrust of 2.4 kN and, with a fuel tuned to the 1 ksec 10 km/sec secondary firing sequences and an efficient double-pulsed shape, the overall efficiency is 80%. mirror 2 ksec 20 km/sec “Specific impulse and other characteristics of elementary propellants for ablative laser propulsion”, Dr. Andrew V. Pakhomov, Associate Professor at the Department of Physics, UAH, 2002. 4 ksec 40 km/sec 8 ksec 80 km/sec AMTEC thermoelectric generator – The alkali metal thermoelectric converter (AMTEC) 12 ksec 120 km/sec is a thermally-regenerative electrochemical device for the direct conversion of heat to electricity using high-voltage multitube modules. These modules accept a heat input

16 ksec 160 km/sec (solar or nuclear) at 900–1300 K and reject it at 400-700 K, producing direct current radiator panel • A thrust of one is 0.75 kN (750 newtons, or 169 lbs, the with an efficiency of 45% and no moving parts. The molten alkali metal (sodium or potassium) is driven around a closed thermodynamic cycle between the heat source weight of the game designer on Earth!). Each additional heat and the heat sink, in a similar fashion to the Rankine MHD heat engine. However, pipes point doubles this. instead of the MHD unit, the AMTEC cycle isothermally expands and ionizes the alkali • An acceleration of one is 0.38 milligees or 0.38 cm/sec2, metal vapor through a solid electrolyte (sodium beta-alumina) for power densities of AMTECs 2 nuclear radiation and each step more doubles this. 100 kWe/m and 2 ton/MWe. “Direct Thermal-to-Electric Energy Conversion for Outer Planet reactor shield Spacecraft”, M. A. Ryan and J.P. Fleurial, Jet Propulsion Laboratory, 2002 pulsed • A size one world has a surface gravity of 0.75 milligees, pulsed neutral antiproton high Z and each additional step doubles this. Size 1 worlds Antimatter bottle reactor – Antimatter fuel can be stored as levitated antihydrogen ice. beam atom beam have the following diameters based on density: comet By illuminating it with UV to drive off the positrons, a bit is electromagnetically extracted nucleus 52 km (only Centaur comets approach this and sent to a magnetic bottle. There it is collided with 60 g of heavy metal propellant (9 size), S-type asteroid 22 km, M-type asteroid 14 km. X 1024 atoms of lead or depleted uranium). Each antiproton annihilates a proton or • Beamed power emits a 60 MW laser beam. Generators neutron in the nucleus of a heavy atom. The use of heavy metals helps to suppress neutral pion and gamma ray production by reabsorption within the fissioning nucleus. produce 60 MWe of electricity. Reactors produce from If regolith is used instead of a heavy metal, the gamma flux is trebled requiring far more 650-2000 MWth of thermal energy, either in neutrons , cooling. A pulse of 5 µg of fuel (3 X1018 antiprotons) contains 900 MJ of energy, and at pions , or plasma jets . Each therm radiates 120 a repetition rate of 0.8 Hz, a power level of 700 MWth is attained. Compared to fusion, antimatter rockets need higher magnetic field strengths: 16 T in the bottle and 50 T in the MWth of heat. (Subscript e = electricity, th = thermal). throat. After 7 ms, this field is relaxed to allow the plasma to escape at 6 keV and 350 atm. • Each burn requires a delta-v (velocity change) of 2.5 These high temperatures and pressures cause higher bremsstrahlung X-ray losses than fusion reactors. km/sec. Each brachistochrone is 5.0 km/sec. Furthermore, the antiproton reaction products are short-lived charged pions and muons, that must • A solar flare die roll of 1 is an M1 flare with an X-ray be exhausted quickly to prevent an increasing amount of reaction power lost to neutrinos. About a power density of 10-5 Watts/m2. Each point more is 4 third of the reaction energy is X-rays and neutrons stopped as heat in the shields (partly recoverable times this. Thus, a die roll of 6 is a X95 (Carrington- in a Brayton cycle), another third escapes as neutrinos. Only the final third is charged fragments -2 2 directly converted to thrust or electricity in a MHD nozzle. D.L. Morgan, “Concepts for the Design of an class) flare with a power density of 10 Watts/m . Antimatter Annihilation Rocket,” J. British Interplanetary Soc. 35, 1982. (For use in this game, to keep the radiator mass • Equipment with a rad-hardness of 1 can withstand a within reasonable bounds, I reduced the pulse rate from 60 Hz to 0.8 Hz.) Robert L. Forward, “Antiproton Annihilation Propulsion”, University of Dayton, 1985. H2 total ionizing dose of 4 X 10-7 krad (Si) without failing. cathode Each point more is 4 times this. For example, equip- Arcjet robonaut – An electric arcjet can act as an arc welder, smelter, or thruster. When + ment with a rad-harness of 5 can survive a Mrad of used for mining beneficiation, it vaporizes the output of a 1T magnetic separator and 3.5 dosage. These numbers are actual industry ratings. tonne impact grinder. When used as a rocket, a working fluid is arc-heated to 12,000 K. This is 4X hotter than other electrothermal engines such as resistojets, since you are not • Solar insolation is 1.38 kW/m2 at 1 AU (1 AU = Earth-Sol - - 2 limited by the melting point of tungsten. However, you will need to periodically replace itsanodes average distance). Maximum sailing thrust is 12.2 N/km thoriated tungsten electrodes. When using hydrogen propellant, the arcjet attains a 2 electric from photon pressure at 1 AU, or 0.002 N/km (2 nPa) specific impulse of 2 ksec with frozen-flow efficiencies of 60%. arc from solar wind dynamic pressure. These values are in nozzle the Earth zone. Each zone closer to Sol doubles them. Atmospheric ISRU scoop refinery – A vehicle with an air intake, coupled to Rankine-cycle • Each water tank (WT) is a 40-tonne bag with a diameter liquefaction gear, can scoop propellant from the atmospheres of Earth, Venus, Mars, Saturn, or Titan. A typical scooping orbit is quasi-elliptical with a periapsis deep within the atmosphere. The system of 4.25 meters. Some rockets use hydrogen as propel- shown requires 54 MWe to overcome atmospheric drag radiators lant; 40-tonnes of LH2 or slush hydrogen is held in a with an electric rocket and 6 MWe to compress and store accelerator air cyro-tank cylinder 7.5 meters in diameter and 16 meters 720 kg/hr of liquid nitrogen or other volatiles. The thermal compressors scoop LN tank long, including active refrigeration for zero boil-off. efficiency is 22% at a turbine inlet temperature of 1400 K. 2 Reichel, Smith, and Hanford, Electric Propulsion Development. liquefaction radiators

Exoglobal Governments – The Outer Space Treaty, The Forgotten Resources of Space – There are no unique raw Regolith Scavenging – Regolith is the veneer of rock dust signed by all the nations represented in this game, materials waiting for us in space (possible exception of 3He). There are a common on asteroids and moons. The stream of solar wind outlaws ‘National Sovereignty’ on all celestial bodies., lot of hydrocarbons on Titan, but because of delta-v costs, it will always causes space weathering, a deposition of wind particles treating asteroids and moons a bit like Antarctica. be cheaper to derive them from marginal locations on Earth, like oil directly into the dust. The atoms are implanted at a shallow Military bases and nuclear weapons in space are shales or biofuels. Even if a platinum-rich asteroid were found, platinum depth (<100 µm) and the finest material is the richest in solar prohibited. Private ownership is not excluded, making would be obtained cheaper by re-opening a depleted low grade mine on wind gases. Wind-enriched particles contain traces of possible homesteading claims and private property Earth. If extraterrestrial raw imports will never be economical, is there any hydrogen, helium, carbon, nitrogen, and other low Z elements rights to space facilities. Because such bodies will be motivation for going there? Increasingly, it is processes rather than raw rare in space. These volatiles can be recovered by scavenging: outside of the jurisdiction of national governments, materials that are important for industry. Space processes can control scooping regolith over wide areas with robonautic buggies, some form of constitutional regime will need to settle the gravity, vacuum, radiation, temperature, and energy density to a processing it to recover the volatiles, and dumping the remains questions of contract and claim disputes, strikes, degree impossible on Earth. These characteristics, the forgotten overboard. The concentrations of volatiles in lunar maria national invasions, terrorist threats, and acts of resources of space, can produce high-strength membranes using regolith is a few hundred ppm of each type. Other valuable violence. Reasonable extra-national precedents to surface tension effects, long whiskers and gigantic laser crystals grown in materials, magnetically or electrophoretically separable from apply are the Spitzberg Islands, the IntelSat Model, microgravity, nano-engineering using ultrapure vapor deposition, strong maria regolith, include iron fines, uranium (2-6 ppm), and ice Condominium Rules, and the Freedom of Navigation glassy materials produced by exploiting a steep temperature gradient, crystals (in permanently shadowed regions). The helium Act. Whatever regime is established will need to treat and alloys mixed by diffusion alone. Relatively small machinofactured and fraction includes 5 to 100 parts per billion of the rare isotope property rights as fundamental, or else investors and nano-produced objects, including pharmaceuticals and bio-tech, will be 3He, valued because it is rare on Earth, and can be used as a investment will never materialize for space ventures. the first space imports to Earth. 13 Phil Eklund, 2009. fusion fuel, using the 3He-D “clean” (aneutronic) fusion reaction. basalt Basalt spinning refinery – Basalt, a common space mineral, can be cast, melt Carbonyl volatilization refinery – The use of gaseous carbon sintered, or spun into continuous or staple fibers. To spin basalt fibers, monoxide (CO) as a catalyst for carbonyl volatilization is the easiest basalt melt is fed to electrically-heated platinum rhodium bushings way to refine metals in space. Solar-heated ores of nickel, iron, containing 200-300 perforations. Superfine fibers (0.2 µm) are drawn by cobalt, and other metals react with CO to form gaseous carbonyls, drum and centrifugal nozzle, and coated with silanes (organosilicon which are then vapor-deposited via CVD molding processes to FeNiCo Fines liquid compounds) to permit adhesion to epoxy composites. Spun basalt can form finished materials. The CO is either recovered by another carbonyls make cloth, bedding, shock absorbers, fine springs, filters, cables (with steam heating cycle, or replenished by heating (to 1300 K) almost any distillation tower coatings), thermal & electrical insulation, woven nozzles and hulls, and basalt type of asteroidal material. The temperatures and pressures 8 5

ablative material. Subramanian et al., 1976, 1979 fiber involved are particularly mild for nickel refinement via the Mond 4 (CO) process: Ni(CO)4 carbonyls form at just 530 K. The residue from CO 2 Fe(CO) Ni(CO) Biophytolytic algae farm refinery Biophytolysis is the use of microorganisms carbonyl extraction of native ferrous metal alloys from M-type Co H O to break down and refine low grade ores and volatiles. Weak solutions of acids 2 asteroidal ores is rich in cobalt and platinum group metals, far CO are dripped through the ore, forming a bacterial liquor that is then electrolyti- more valuable than gold. The cobalts are separated from the gas oven oven oven cally or chemically processed. Biophytolytic processes do not require much platinums by very high-pressure extraction with CO, by extraction energy, and have a theoretical efficiency of 40%, but they are very slow. green alga with CO-H2O mixtures as the carbonyl hydride, or by wet chemical Thermophyllic bacteria extract nickel, zinc, and cobalt; sulfate-reducing techniques. John S. Lewis and Melinda L. Hutson, “Asteroidal Resource bacteria obtain gold, copper, and uranium. Cyanobacteria and green algae, Opportunities suggested by Meteorite Data”, University of Arizona, 1993. bioengineered for radiation and O2 tolerance, oxidize water at room tempera- tures, producing hydrogen and oxygen. This process is carried out by chloroplast Carbochlorination refinery – Metal sulfates may be refined by exposing photosynthetic enzymes, which split water to obtain electrons, and then thylakoid a mixture of the crushed ore and carbon dust to streams of chlorine cyanobacteria gas. Under moderate resistojet heating (1123 K) in titanium chambers excite these electrons with photons so they can reduce 2H+ to H2. Molecular H2 O2 complexes involved in mediating electron flow from water to carbon-fixing or sulfate (Ti resists attack by Cl), the material is converted to chloride salts such Al2Cl3 ores collection hydrogen-production reactions make up the photosynthetic electron-transport as found in seawater, which can be extracted by electrolysis. The trays Taq thermophyllic & example shown is the carbochlorination of Al2Cl3 to form aluminum. chain found in the thylakoid membranes of cyanobacteria and green algae. thermodesulfobacteria Chaff from the algae farm is used as an organic substrate. Al is valuable in space for making wires and cables (copper is rare in retort Au, Cu, U, G. Jeffrey Taylor and Linda Martel, Hawaii Institute of Geophysics and Planetology, 2001. space). The electrolysis of Al Cl does not consume the electrodes + CO Ni, Zn, Co 2 3 3 Cl 2

nor does it require cryolite. However, due to the low boiling point of radiator Brayton turbo generator – A solar or nuclear heat source can generate Al Al2Cl3, the reaction must proceed under pressure and low tempera- CO to electricity via a closed-loop Brayton cycle. Unlike the Rankine cycle, in which tures. Other elements produced by carbochlorination include titanium, methan- the working fluid changes phase, the Brayton cycle uses an inert gas such potassium, manganese, chromium, sodium, magnesium, silicon and ation as helium. This is expanded through a power-producing turbine, and then also (with the use of plastic filters) the nuclear fuels 235U and 232Th. Al2O3 + C circulated through a radiator for cooling and reuse. Typically, heated helium Both C and Cl2 must be carefully recycled (the recycling equipment enters the turbine at 1700 K and 24.5 atm. A mass breakdown: 3600 rpm AC dominates the system mass) and replenished by regolith scavenging. turbine with a diameter of 2.6 meters: 4.5 tonnes, alternator-generator: 12 Dave Dietzler, www.moonminer.com tonnes, recuperator: 12 tonnes, compressor: 10 tonnes, transformers: 20 Cl2 tonnes. The gaseous fluids used in the Brayton cycle have heat-transfer Cascade photovoltaic generator – A photovoltaic cell generates a coefficients about 50 times lower than the liquid fluids used in the Rankine coolant voltage when radiant energy falls on the boundary between dissimilar cycle. As a result, the closed Brayton cycle has an inherently lower thermal flow substances. A high efficiency example is the multijunction cascade efficiency (19% vs. 22%). cell, made from elements from the third and fifth columns of the periodic table. Three junction cells arranged in tandem at 100X solar collection Bubble membrane radiator - This high-temperature concept uses a trough concentration achieve 50% conversion efficiency at 350 K. Radiation- spinning bubble-shaped membrane to reject waste heat. A two-phase hardness is improved by adding an electric field in the base layer of the LiF working fluid (hot liquid or gas) is centrifugally pumped and sprayed on the membrane lowest-resistance middle cell, and EOL current matching of sub-cells Al bubble cascade interior surface of the bubble. The fluid wets the inner surface of the sphere to the highest-resistance top cell. The absorption range is increased fiber and is driven in the form of a liquid film by centrifugal force to the equatorial by introducing light down narrow (200 µm) woven optical fibers coated periphery of the sphere. As the liquid flows along the inner surface of the with indium-tin oxide. The fiber bundles act as their own radiator. Other envelope it loses heat by thermal radiation from the outer surface of the nano-tech enhancements include double-hetero wide band-gap tunnel active balloon. The use of membranes woven from space-produced carbon junctions, precise lattice-matching to Ge substrates, and 1.96 eV layer 2 PEDOT nanotubes and cermet fabrics offers a specific area of 7 kg/m , radiating liquid droplet AlInGaP top cells. Enhanced cascade photovoltaics attain optical sprayers 2 fiber ITO from one side at 800 K. Liquid metal pumps return the liquid out of the 2 ton/MWe and 2 kg/m . Takamoto, Kaneiwa, Imaizumi, and Yamaguchi, light sphere through rotated shaft seals to its source. Koening, 1985. “InGaP/GaAs-based multijunction solar cells,” Progress in Photovoltaics, Aug 2005.

Buckytube filament radiator - Waste heat may be roller Cat fusion z-pinch torch robonaut – A plasma torch driven by Zeta Pinch 70 m stationary catalyzed fusion may be used in ore refining or waste recycling. rejected by moving thousands of loops of thin (1 mm) filament drum flexible “Buckytubes” (carbon nanotubes), which radiate their thermal Fusion occurs in a zeta-pinch, a high-density fast-pulsed plasma B I load prior to return to the heat exchanger. Cables constructed of Arm-chair focusing device, using a vanadium-gallium (V3Ga) superconductors plasma and aluminum stabilizers. The confining force of the zeta-pinch is a type nanotubes are the strongest cables known, with design tensile strengths longitudinal about 70% of the theoretical 100 GPa value. The moving filaments are heated flow passage “self-generated” magnetic field (a field set up by electric currents in the by direct contact around a molybdenum drum filled with the heated working plasma itself). The megamp electric current (I) is in the zeta direction, waste or fluid, and then extended into space a distance of 70m by rotational inertia. and the resulting magnetic field (B) is in the theta direction. catalyst ores Their speed is varied according to the temperature radiated (from 273 K to A variety of hypothetical exotic particles catalyze the D-T and D-D fusions. Catalyst escape is minimized by the Z-pinch 1300 K). The loops are redundantly braided to prevent single point failures from processed micrometeoroids. Each element is heat treated at 3300 K to increase the configuration, and further minimized downstream by materials high-temperature staged cascades of modulated nanosorters, catalyst thermal conductivity through graphitization to about 2500 W/mK. recovery Richard J. Flaherty, “Heat-transfer and Weight Analysis Of a Moving-Belt Radiator System for which are themselves continually destroyed and rebuilt. Waste Rejection in Space”, Lewis Research Center, Cleveland, Ohio, 1964. Cermet NERVA thruster – The NERVA (Nuclear Engine for Rocket Buckyball C60 photovoltaic generator – The C60 “Buckyball” molecule Vehicle Application) system captures the neutronic energy of a nuclear shield is a fullerene carbon allotrope, about a nanometer across, composed of ITO CuPC 10 nm reaction using a heat exchanger cooled by water or liquid hydrogen. 60 carbon atoms arranged in a hollow sphere. It has semiconducting C60: CuPC 10 nm The exchanger uses thin foil or advanced dumbo fuel elements with and magnetic properties, up to its Curie temperature around 500 K. In C60 20 nm cermet (ceramic-metal) substrates, jacketed by a beryllium oxide BCP 8 nm dumbo its amorphous form, Buckyball C60 is a semiconductor with a bandgap Ag 15 nm neutron reflector. The chamber temperature is limited to 3100K for core of 2.5 eV. By intercalating dopants between the Buckyballs, the Rubrene antenna 125 nm light the extended operational life of the solid fuel elements, which can be reflector conductivity can be increased. The organic photovoltaic device fission, fusion, or antimatter. At this temperature, the disassociation of Ag 60 nm illustrated uses charge-generating layers of copper phthalocyanine molecular H2 to H significantly boosts specific impulse at chamber LH2 (CuPc)/fullerene (C60) over a light-absorbing rubrene antenna. Radiation absorbed pressures below 10 atm. A propellant tank pressurized to 2 atm expels by the antenna is transferred into the charge generating layers via surface plasmon the LH2 coolant into the exchanger without the need for turbopumps. polaritons. The antenna tunes the cavity to absorb light strongly, improving the This open-cycle coolant is expanded through a hydrogen-cooled quantum efficiency to 85%. Membrane photovoltaic C60 films, centrifugally- nozzle of refractory metal to obtain thrust. The efficiencies are 96% thermal, 2 tensioned and supported by wires, have a specific area of 1.5 kg/m . T.D. Heidel, J.K. 76% frozen-flow (mainly H2 dissociation, less recombination in the nozzle), and Mapel, K. Celebi, M. Singh, M.A. Baldo, “Analysis of surface plasmon polariton mediated energy 96% nozzle. A 940 MW heat exchanger yields a thrust of 134 kN, and a transfer in organic photovoltaic devices”, Proc. of SPIE, 6656, 2007. th specific impulse of 1 ksec, at a power density of 340 MW/m3. Altseimer, et al., “Operating Characteristics and Requirements for the NERVA Flight Engine,” AIAA Paper 70-676, 14 June 1970. 100 probe: thrust 200 400 freighter: thrust 700 tug: thrust ton +1 ton scout: +0 thrust ton -1 ton -2 Tank #1 Tank #2 Tank #3 Tank #4 Tank #5 Tank #6 Tank #7 Tank #8 1 - 2 dry 3 dry

= Wet Mass Modifier 4 dry = Cargo Loading 5 ROCKET DIAGRAM dry

Crew card – Each Crew card represents the consumables and life De Laval nozzle thruster – The familiar converging-diverging shape of the De nuclear support for eight hardy specialists. They are housed in 16 tonne Laval nozzle is designed to accelerate a propellant flow to supersonic speeds. plasma inflatable Bigelow habitation modules (1760 m3), made of Its operation relies on the different properties of gases flowing at subsonic and source Vectran (a “bulletproof” textile). Paired modules, 45 meters supersonic speeds. The gas flow through a de Laval nozzle is isentropic (gas apart, are rotated at 5 RPM to provide 0.6 G of artificial gravity. entropy is nearly constant). As the nozzle constricts, the gas speeds up to Food and atmospheric conditioning is provided by maintain a constant flow rate. At subsonic flow the gas is still compressible; so H2 crops that grow without soil but have their roots misted airlock 1 sound will propagate through it. At the throat, the gas velocity locally becomes with nutrients daily. A plot 25 meters across provides all sonic (Mach number = 1.0), a condition called choked flow. As the nozzle

the foodstuffs for the year. Waste heat from plant widens, the gas expands and the gas flow increases to supersonic velocities H2 evaporation requires low temperature radiators. A 10 centrifuge 1 (Mach number > 1.0). As viewed in the frame of reference of the nozzle, no tonne life support module requires 12 kWe, and clockwise sound propagates from supersonic flows. Thus the flow rate will not increase communications from Ka band antennas require at choked flow, no matter how low the exit pressure is. The nozzle illustrated has an superconducting centrifuge 2 another 0.2 MWe. A charged plasma sustains a high coil counter- area ratio (ratio of throat area to exit area) of 30:1, and a nozzle efficiency of 90%. It is electrical potential (10 GeV) about the hab unit for clockwise regeneratively-cooled by passing liquid hydrogen coolant through channels surround- protection against most galactic cosmic rays. When a ing the nozzle wall. The heated hydrogen is then injected into the rocket as propellant. charged particle intercepts this magnetic field, its path Li D&T SIDE curves to avoid the occupants. If a solar storm erupts, the antenna VIEW D-T fusion Tokamak reactor – Of all the fusion reactions, the easiest to crew must evacuate into a small (8-meter dia) storm shelter. attain is a mixture of the isotopes of hydrogen called deuterium and tritium The shelter is shielded by 100 kg/m2 of polyethylene (12 cm (D-T). This reaction is “dirty”, only 20% of the reaction power is charged thick), plus water propellant and graphite. Robert Bigelow, 2007. particles (alphas) that can be magnetically extracted with a diverter for torus power or thrust. The remaining energy (neutron, bremsstrahlung, and Curie point radiator - A ferromagnetic material heated Fe cyclotron radiation) must be captured in a surrounding jacket of cold droplet above its Curie point loses its magnetism. If molten sheet dense Li plasma. The heated lithium is either exhausted as open-cycle droplets of such a substance are slung into space, coolant, or recirculated through a heat engine (to generate the power they radiate heat and solidify. Once below their Curie Fe dust sheet needed for the microwave plasma heater). temperature, they regain their magnetic properties and can be below Curie point electro- The 2 GWth magnetically-confined reactor shown uses eight poloidal super- shepherded by a magnetic field into a collector and returned to magnetic conducting 30 T coils, twisted into a Tokamak configuration. These weigh broom the heat exchanger. A 120 MW system operating at 1200 K includes a 13 22 tonnes with stiffeners and neutron shielding. The pulsed D-T plasma, tonne magnetic heat exchanger and a rotating dust recovery electromagnet containing tens of megamps, is super-heated by 50 MW of microwaves or magnetic on a 25-meter boom, plus 7 tonnes of dust spread in a spiraling disk colliding beams to 20 keV. The Q (gain factor) is 40. Closed field line nozzle 27-meters in diameter (35 kg/m2). The usual medium is iron dust, which has a devices such as this can ignite and burn, in which case the Q goes to infinity and Curie point of 1043 K and is easily scavenged by magnetic beneficiation from microwave heating is no longer needed. However, since ignition is inherently unstable regolith. M.D. Carelli, 1989. (once ignited, the plasma rapidly heats away from the ignition point), the reactor is kept at slightly below ignition. Fuel is replenished at 24 mg/sec by gas puffing to maintain a CVD molding refinery – Metal-walled structures and complex metal parts are plasma ion density of 5 X 1020/m3 at 26 atm. At a power density of 250 MWth /m3, the readily produced through chemical vapor deposition (CVD), a molding process lithium-cooled first wall has a neutron loading of 1 MW/m2 and a radiation loading of 5 that requires no machining for the final product. Normally a nickel vapor is MW/m2. More advanced vortex designs, which do away with the first wall, separate the deposited, which is strong, ductile, corrosion-resistant, versatile, common in hot fusion fuel from the cool lithium plasma by swirling the mixture. The thermal efficiency space, and the easiest ferrous metal volatilized using CVD. The CVD process is 50% in open-cycle mode. Williams, Borowski, Dudzinski, and Juhasz, “A Spherical Torus Nuclear distributes nickel carbonyl vapors over a mildly solar-heated surface, where Fusion Reactor Space Propulsion Vehicle Concept for Fast Interplanetary Travel,” Lewis Research Center, they decompose and deposit structurally-sound nickel on a mandrel. 1998. (The Tokamak used in High Frontier is a smaller lower tech version of the Lewis design, which uses aneutronic 3He -D fuel.) Deposition occurs at mild temperatures (450 K) and high purity (<.02% carbon coolant impurities). A vapor stream of 90% Ni(CO) carbonyl and 10% CO creates to boiler 4 Dual-mode fission reactor - When struck by a thermal neutron, a fissile forms and shapes with phenomenal leveling and corner-filling. Shape-welding shield (building up weld material around joints) can produce vessels many tons in nuclide splits into fragments plus energy. For example, the fission of the 235 mass. The metal vapors may also be used to infiltrate pre-forms of carbon U atom produces 165 MeV of energy plus 12 MeV of neutral radiation whiskers or open cell foams. CVD can also be used with mixed nickel and iron (gammas and a couple of fast neutrons). The fast neutrons must be thermalized by a low Z moderator (a surrounding 80cm blanket of D O, fines, as from a type M asteroid. The carbonyls formed will be mixed, and a 2 CVD Be, liquid or gas D2, or CD4), which returns enough thermal neutrons to Fe-Ni alloy will be deposited. The synthesis of iron carbonyls is not as simple deposit as for nickel, requiring higher pressures and a carbon dioxide-water the core to sustain the chain reaction. (Thermal neutrons diffuse through vapor mix. The work takes place inside inflatable chambers that the reactor like a low pressure gas.) Alternatively, a molybdenum neutron reflector can be used. Much of a reactor’s mass is constant, regardless of condense and recycle the CO, H2O, and unreacted gases. reflector However, due to the near instant disassociation of escaped carbonyl vapor power level. Therefore, nuclear power sources are more attractive at higher CO + Ni(CO)4 power levels. The 650 MWth system illustrated is dual-mode: it can either carbonyl in a vacuum, some replacement of CO is needed. base of mold (unheated & insulated) William C. Jenkin, Galactic Mining Industries, 2008. generate electricity, or directly exhaust coolant for thrust. It uses a fast pulsed heavy water reactor with fuel tubes interspersed with cooling tubes. The coolant is ice-pellet injector D-D inertial fusion robonaut – A “target” of fusion fuel can be lithium, passed to a potassium boiler at 1650 K. For closed-cycle power generation pulsed brought to ignition by inertial confinement: the process of lasers or (output of 60 MWe), potassium vapor is passed to a static (AMTEC) or dynamic (turbine) particle solar compressing and heating the fuel with beamed energy arriving beams heat engine at 19% thermal efficiency. For open-cycle thrust (125 kN at a specific radiation from all sides. The target is a snowflake of deuterium, the impulse of 1 ksec), hydrogen is heated in a heat exchanger at 94% efficiency. ablative nozzle “heavy” isotope of hydrogen, imploded and fused with a payload combination of lasers and deuterium particle beams. The Electric sail – The solar wind dynamic pressure is about 2 nPa at one AU. An illustrated design uses combined input beam energy of 38 MJ, mirrors electric sail generates nanothrust from this particle stream in a manner similar arrayed in a sphere surrounding the ejected pellet target. A 2 to a mag sail, except that electric rather than magnetic fields are used. Its electron microexplosion gun gram ice pellet is ejected each second. The outside 99% of the point geometry employs hundreds of long thin conducting wires, rotating with a pellet is ablated away within 10 ns, super-compressing the period of 20 minutes to keep them in positive tension. A solar-powered deuterium fuel at the core to a density of a kilogram per cubic electron gun (typical power is a few hundred watts) keeps the spacecraft and centimeter. The T and 3He products are catalyzed to undergo further fusion sail in a high positive potential (up to 20 kV). This electric field surrounds each until all that remains is hydrogen, helium and neutrons. (Neutrons comprise wire a few tens of meters into the surrounding solar wind plasma. Therefore the 36% of the reaction energy.) Fractional burn-up of the fuel (30%) is twice that solar wind protons "see" the positively-charged wires as rather thick obstacles. of magnetic confinement systems, which implies a 40% higher fuel economy. It is this multiplication factor that allows sails using the solar wind to outperform those using photon pressure, which is 5000 times stronger. Furthermore, the The energy gain factor (Q) is 53. C60 electric sail thrust force varies as (1/r)^{7/6} from Sol, compared to the photon photovoltaic For a 500 MWth reactor, 320 MW of charged particles are produced, useful for panel either thrust or metals refining. About 105 MW of fast neutrons escape to pressure, which varies as the inverse square distance. Each 100 km tether, space, but another 75 MW of them are unfortunately intercepted by the massing but a kilogram, generates 0.01 N of thrust. Simultaneously it also attracts structure. About two thirds of this energy must be rejected as waste heat, but electrons from the solar wind plasma, which are neutralized by the electron gun. the remainder is thermally used to generate electricity or to breed tritium. The Potentiometers between each tether and the spacecraft control the attitude by latter is added to the fuel to facilitate the cat D-D pellet ignition. The system fine-tuning the tether potentials. Additionally, the thrust may be turned off by simply provides thrust when an ablative nozzle is added. This nozzle, made of nested switching off the electron gun. Each 20 µm tether is redundantly interlinked for layers of whisker graphite, counts as both shadow shield and propellant. robustness against meteoroids. Electric sails must avoid magnetospheres, since there is R. Hyde, “A Laser Fusion Rocket for Interplanetary Propulsion,” 34th International Astronautical no solar wind inside these zones. Pekka Janhunen, “Electric Sail”, 2004. P. Janhunen and A. Conf., AIF Paper 83-396, 1983. (To keep radiator mass under control, I reduced the pellet Sandroos,“Simulation study of solar wind push on a charged wire” 2007. repetition rate from 100 Hz to 1 Hz). 15 Electroforming refinery – A bath of electrolyte-plating solution Flux-pinned superthermal radiator – Variable configuration radiators take metallic spindle manufactures thin-walled metal structures by deposition onto a ions advantage of the surprising physics of high-temperature flux-pinning mandrel having the inverse contour. Mandrels are prepared from superconductors. These materials resist being moved within magnetic cast or spun basalt, coated with aluminum. A robonaut monitors mandrel fields, allowing stable formations of elements. No power or active the electrical current densities as a function of metal deposition feedback control is necessary. The radiating elements fly in a flux-pinned rate. Nickel and iron are the most common electroformed anode formation, not physically touching, but connected by superthermal ribbon. extraterrestrial metals. The need for an electrolyte-plating solution electrolyte Superthermal compounds hypothetically conduct heat as effortlessly as requires the electroforming unit to be pressurized and operated superconducting materials conduct electricity. The radiating surfaces are heat filtered source only in an accelerated frame. The anode plate is consumed during electrolyte filter graphite foams, which have both a high emissivity (0.9) and a high thermal the forming process, but lunar or asteroidal iron and titanium are conductivity (1950 W/m°K) if the heat conducts in a direction parallel to widely available for this purpose. The electrolyte is recycled. the crystal layers. Operating at 928K, the superthermal radiator has a R. Freitas Jr., Proceedings of the 1980 NASA/ASEE Summer Study, Space Initiative/XRI. specific area of 17 kg/m2 and 76 kWth/m2. Dr. Mason Peck, 2005. solar Electrophoretic sandworm robonaut – The panels Flywheel compulsator generator – A low-density disk spun in a containment illustration depicts a big vehicle designed for vacuum at 80000 rpm stores considerable energy in its angular beam stationary regolith devolatilization. It consists of a Schaufel- target momentum. Twin wheels, each 1.5 meter in diameter and 1.2 rad (shovel-wheel) and conveyor belts to transport meters thick and made of graphite stiffened with carbon conveyor material to a central hopper, which holds a soil belt whiskers, together weigh 5 tonnes. They spin on a single axle pressurizer, grinding mill and heater, solid - vapor suspended by superconducting YBCO magnetic bearings. The beamhinge reflector radiators separator, volatiles collector bag, tailings disposal, system includes rectification, filtering, and inversion electronics, magnetic and gas cleaner / reheater / repressurizer. Power as well as fuzzy logic dampening of shaft vibration. A compulsator suspension comes from a solar concentrator, pivoted to Schaufelrad pivot (short for compensated pulsed alternator) provides the power supply. Up to 200 concentrate sunlight onto a heat engine target. GJ of solar energy is stored, with a peak load of 600 MWe. The specific power Regolith is beneficiated by removing its irons magnetically, and then dumping it into a and energy are 7.6 kW/kg and 2.5 MJ/kg, not including solar thermionic cells. high-voltage zone electrophoretic tank. (Electrophoresis beneficiates charged particles in an electric field according to the magnitude and sign of the electrophoretic mobility.) Flywheel mining tractor robonaut – An electric tractor is The term “sandworm” is inspired by the creatures appearing in the novels of Frank Herbert, capable of scooping and hauling 120 tonnes of iron fines or which filter huge amounts of sand for tiny amounts of valuable “spice”. Here, the “spice” volatiles per year over rugged terrain, using a 6 MW (8500 microwave is helium 3, a substance not found on Earth, but present in tiny amounts in asteroidal horsepower) flywheel motor. The flywheel is recharged via a rectenna beam and lunar regolith. Helium 3 is necessary for the clean 3He-D fusion reaction, and thus in microwave rectenna. Its dynamic active neutron spectrometer target the future may become more valuable than oil. A 40-tonne sandworm of the size homes in on hydrogen signals indicating ice deposits or crystals. depicted operates with 350 kWe derived from beamed power (using a 12 MW beam). It An auger digs through the regolith, and breaks up agglutinates reflector volatiles processes 9 million tonnes of regolith a year, yielding 110-tonnes of water propellant, with impact grinders and screens. With a 7 tonnes/hr storage solar 200-tonnes of hydrogen propellant, and 33-kg of helium 3 fuel. Based on Gajda NASA oven throughput of regolith, a one Tesla magnetic separator sorts fly- academy model Mark 2 and 3 sandworms, and Lunarpedia 2007 discussions. 11 kg/hr of free iron, titanium ilmenite grains, and magnetic wheel oxides of iron, cobalt, and nickel. If volatiles are required, a iron Electrostatic membrane radiator – This heat-rejection concept, large solar concentrator is unfurled to roast the ice crystals batteries fines magnetic storage drum separator also called a liquid-sheet radiator, encloses radiating liquid within out of the regolith. Dave Dietzler, www.moonminer.com electron gun a transparent envelope. It consists of a spinning membrane disk injector inflated by low gas pressure, with electrostatically-driven coolant Free electron laser robonaut – An intense and rapidly alternating set of lineac circulating on its interior surfaces. The liquid coolant is only 300 µm static magnetic fields, called a "wiggler", efficiently converts the energy accelerator thick and has an optical emissivity of 0.85 at a temperature of 1000 K. in a relativistic electron beam into coherent photons. This is the basis of wiggler An electric field is used to lower the pressure under the film of coolant, the free electron laser (FEL). Shown is a 125 MWe FEL with an 80-meter so that leakage through a puncture in the membrane wall is avoided. electron accelerator. The acceleration may either be continuous, using storage ring The membrane has a specific area of 4.3 kg/m2 and 51 kWth/m2. resonant electrical cavities powered by high frequency electrical power, Shlomo Pfeiffer of Grumman, 1989. or it may be pulsed with a set of microwave "transformers" that use the electron beam as the effective secondary winding. The wavelength is wiggler electron ETHER charged dust radiator – To avoid the evaporation tunable in the 300 nm repetitively pulsed range. The electrons are trap lineac losses suffered by radiators that use liquid droplets in space, decelerated, and recirculated. The FEL's conversion of electrical decelerator dust radiators use solid dust particles instead. If the particles energy to light energy is remarkably efficient (40% overall). are electrostatically charged, as in an electrostatic thermal heat beam source charged director radiator (ETHER), they are confined by the field lines between dust Free radical hydrogen reactor – Free radicals are single atoms of Van de Graaff paths a charged generator and its collector. If the spacecraft is electrostatic elements that normally form molecules. Free radical hydrogen (H) dust charger compensation charged opposite to the charge on the particles, they execute has half the molecular weight of H2. If used as propellant, it doubles coils an elliptical orbit, radiating at 1200 K with a specific area of 71 kg/m2 the specific impulse of thermodynamic rockets. If used as fuel, its and 213 kWth/m2. The dust particles are charged to 10-14 coulombs specific energy (218 MJ/kg) produces a theoretical specific impulse to inhibit neutralization from the solar wind. Prenger 1982. of 2.13 ksec. Free radicals extracted by particle bombardment are plenum cooled by VUV laser chirping, and trapped in a hybrid laser-magnet trapped Explosive-pumped gas dynamic laser robonaut – A laser pumped as a Bose-Einstein gas at ultracold temperatures. A Pritchard-Ioffe radicals nozzles by nuclear bombs rather than solar heat achieves the high pulse micro- trap keeps their mobile spins aligned, using the interaction of the fission peak power output and high efficiency (30%) applicable in space cavity mirror atomic magnetic moment with the inhomogeous magnetic field. The weapons. A typical wavelength is 10.5 µm (CO2, N2 adiabatic trapping density of >1014 atoms/cc is much higher than in Penning expansion). After heating, the gas is expanded through a traps. Free radical deuterium that has been spin-vector polarized is pinch Ioffe supersonic nozzle, and flows through a duct. The lower vibrational stable against ionization and atomic collisions. Because of its large coils bars state eventually relaxes, but the higher states do not, achieving a diffuser fusion reactivity cross-sectional area, it makes a useful fusion fuel. Robert L. Forward, 1983 population inversion for a photon avalanche. In this way megajoule IR laser output annular laser pulses can be released within 10 nanoseconds. The explosive Hall Effect thruster – This ion rocket accelerates ions using the Mg recirculated anode/gas source can be microfission or fusion devices, or antimatter. gas electric potential maintained between a cylindrical anode and distributer negatively charged plasma which forms the cathode. To start the ilmenite cyclone Fluidized bed refinery – In a fluidized bed refiner, a fluid (gas or fines collector engine, the anode on the upstream end is charged to a positive liquid) is passed through a granular solid ore (such as regolith) at gas potential by a power supply. Simultaneously, a hollow cathode at high enough velocities to suspend the particles and cause them to the downstream end generates electrons. As the electrons move behave as though they were also a fluid. The heat and agitation upstream toward the anode, an electromagnetic field traps them Hall fluidized current increases the reaction rate. Ilmenite fines (grains of FeTiO3 electro- bed into a circling ring at the downstream end. This gyrating flow of statically separable from lunar regolith) may be reduced in a electrons, called the Hall current, gives the Hall thruster its name. fluidized bed, using either hot hydrogen (1270 K), or carbon The Hall current collides with a stream of magnesium propellant, Mg+ Mg+ monoxide. This obtains iron fines and titanium dioxide particles. H2 distributor creating ions. As magnesium ions are generated, they experience TiO2 In either case, titanium is obtained from the reactants by acid O2 Fe the electric field between the anode (positive) and the ring of electrons (negative) leaching, carbonyl CVD, or vacuum heating at high-temperature. H2O and exit as an accelerated ion beam. A significant portion of the energy required Pure titanium is obtained by electrolysis in FFC Cambridge cells. electrolysis to run the Hall Effect thruster is used to ionize the propellant, creating frozen flow The titanium part is finished with a grinder, e-beam welder, drill losses. This design also suffers from erosion of the discharge chamber. On the press, small lathe, and small rolling mill. Dave Dietzler, 2005. plus side, the electrons in the Hall current keep the plasma substantially neutral, 16 allowing far greater thrust densities than other ion drives. Novosti Kosmonavtiki, 1999. H -O chemical thruster – (As used by the Kuck mosquito and 3He-D fusion mirror cell reactor – Helium 3 is an isotope of helium, and forward field-reversed 2 2 mirror choke cell certain crew cards.) The combustion of the cryogenic fuels deuterium (abbreviated D) is an isotope of hydrogen. The 3He – D hydrogen and oxygen produces an ideal specific impulse of 528 fuel tank fusion cycle deposits 97% of its fusion energy in the plasma as fast seconds. The product is water, which is exhausted through a (LH2) charged particles (compared to 20% in the D - T cycle). Magnetic neutral plasma beam torus converging-diverging tube called a De Laval nozzle. The engine gas tubes pinched at both ends are called mirrors. Contrasted to toriods, generator illustrated is similar to the Space Shuttle main engine, with a for starting their linear geometry achieves superior ratios of plasma to magnet specific impulse of 460 seconds (This scales to 8 for the game fuel pressures (ß >30%) and higher power densities needed for reaching the consumption rating. However, I use 6 instead, as 8 is almost 50 keV operating temperature. The mirror shown uses 11T supercon- unplayable.) The De Laval nozzle has a 180:1 area ratio, and is oxidizer tank ducting magnetic coils, plus choke coils for reflection at the ends. The (1 of many) (LO2)

regeneratively-cooled with liquid hydrogen. The chamber magnets weigh 12 tonnes, plus another 24 tonnes for 60 cm of magnet tandem mirror cell temperature is 3500K, and the chamber pressure is 2.8 MPa. The radiation shielding and refrigeration. A 3He – D mirror has low radiation engine has a thermal efficiency of 98%, a mixture ratio of 5.4, and a losses (20% bremsstrahlung, 3% neutrons) compared to end losses neutral frozen-flow efficiency of 55%. A 2000 MWth chamber generates turbine (77% fast charged particles). These losses limit the Q to about unity beam 440 kN of thrust and a thrust to weight ratio of one gravity. Space combustion and prevent ignition. (This is not a problem for propulsion, since Transportation Systems, American Institute of Aeronautics and Astronautics, 1978. injector chamber reaching break-even is not required to achieve thrust. The plasma is held aft field-reversed in stable energy equilibrium by the constant injection of auxiliary microwave mirror choke cell H2-O2 fuel cell generator – Regenerative alkaline fuel cells convert or e-beam heating.) The Q can be improved by a tandem arrangement: stacking chemical energy directly into electricity, in this case using identical mirror cells end to end so that one’s loss is another’s gain. The exhaust exiting hydrogen as the fuel and oxygen as the oxidant. At the anode, e- one end can be converted to power by direct conversion (MHD), and the other end’s hydrogen gas combines with hydroxide ions to produce water H+ exhaust can be expanded in a magnetic flux tube for thrust. Mirrors improved by vortex vapor plus free electrons. The specific energy of the fuel alone is O2 + 4H+ + 4e- 2H2O technology, called field-reversed mirrors (FRM), introduce an azimuthal electron current 13.5 MJ/kg. At the cathode, oxygen and water plus returning H2 + which creates a poloidal magnetic field component strong enough to reverse the polarity electrons from the circuit form hydroxide ions that are recycled 2H2 4H + 4e- O2 of the magnetic induction along the cylindrical axis. This creates a hot compact toroid anode back to the anode. Either proton exchange membranes (PEM), or cathode H O electrolyte 2 that both plugs end losses and raises the temperature of the scrape-off plasma layer microbes that transfer electrons to the electrode as they fourfold (to 2.5 keV), corresponding to a specific impulse of 32 ksec. Mirrors, like all metabolize, are used to produce the current. PEM catalyst magnetic fusion devices, can readily augment their thrust by open-cycle cooling. The water produced is separated back into H2 and O2 by solar-powered M.J. Schaffer, “Considerations for Steady-State FRC-Based Fusion Space Propulsion”, General Atomics cyanobacteria vats. To store the hydrogen, a system is needed that can latch Project 4437, 2000. HeAr onto H2 molecules in adequate numbers, yet relinquish them readily when medium feedback heated. Titanium-crusted carbon nanotubes meet both requirements. A 200 He-Ar nuclear-pumped laser robonaut – A laser of helium and argon mirror GJ fuel cell stack has a peak load of 600 MW , and a volume of 300 m3. The gases uses the transmutation of helium 3 in a neutron flux (i.e. the 3He window 235U e film specific power and energy are 15 kW/kg and 5 MJ/kg. Operating tempera- (n,p) D reaction) as the energy source to create inverse populations of tures are 400K with a thermal efficiency of 70%. energy levels in the gases. These lasing populations surrender their micro- energy as a laser beam by the special optical system illustrated. The fission H-B cat. inertial robonaut – The fusion of hydrogen 2 and boron 11 is catalyst neutron flux trap neutron flux can be provided by a fast breeder reactor, or a curium fission a clean reaction, releasing only 300 keV alpha particles, which can be fragments baseball microfission bomb. The He-Ar lazing gases are contained in a battery of magnetically directed. However, the H-B fusion will not proceed at magnet rods surrounding each shot. The output beam wavelength is in the X-ray output temperatures less than 300 keV unless catalyzed using exotic range, which has a low beam divergence and a high energy per photon. window particles. One possibility: replace the electrons in H-B atoms with X-ray laser stable massive leptons such as magnetic monopoles or fractionally- H-6Li fusor reactor – A Farnsworth-Bussard fusor is little more than two charged particles (the existence of these is hypothetical). The charged concentric spheres dangling in a vacuum chamber, producing H2 ablative resulting exotic atoms can fuse at “cold” temperatures, allowing the material fusion through inertial electrostatic confinement. Electrons are emitted 6Li exotic catalysts to be recycled. from an outer shell (the cathode), and directed towards a central grid (the A second possibility is to use antiproton-catalyzed microfission to initiate ion guns anode). The grid is a hollow sphere of wire mesh, with magnetically- e- the H-B fusion. If a hundred billion antiprotons at 1.2 MeV in a 2 nsec e- shielded elements so that the electrons do not strike them. Instead, they e- e- electron 235 e- cloud pulse are shot at a target of three grams of HB: U in a 9:1 molar ratio, the zip right on through, oscillating back and forth about the center, creating ae-beam e- uranium microfission initiates H-B fusion and releases 20 GJ of energy. One deep electrostatic trap for the ions of lithium 6 and hydrogen that form shot with 145 mg of H-B fuel imploded every 20 seconds produces 500 MWth. the fusion fuel. With a one meter diameter grid and a fuel consumption A shell of 200g of lead about the fuel thermalizes the plasma from 35 keV rate of 7 mg/sec, the fusion power produced is 360 MWth. Half of this average to 1 keV, low enough that this radiation can be optimally transferred energy is bremsstrahlung X-rays, which must be captured in a lithium to thrust using a magnetic or ablative nozzle at 73% efficiency. The ejected heat engine. The other half are isotopes of helium (3He and 4He), each at mass per shot is 2.4 kg. Catalyzed fusion enjoys an excellent thermal about 8 MeV. Overall efficiency is 36%. Since both products are doubly MHD efficiency (86%) and thus a good thrust/weight ratio (3.2 milli-g), making it one charged, a decelerating 4 MeV electric field produces two electrons from electric e-beam of the best engines in the game. The specific impulse ranges between 8 and each, generating an 18 amp current at extremely high voltage. An generator generator 16 ksec, depending whether spin-polarized free radicals are used as the electron gun using this 4 million-volt energy emits electrons at relativistic plasma hydrogen fuel. G. Gaidos, et al., “Antiproton-Catalyzed Microfission/Fusion Propulsion speeds. This e-beam can be used to generate electricity using MHD, or Systems for Exploration of the Outer Solar System and Beyond”, Pennsylvania State University, may form the input for a free electron laser. R W. Bussard and L. W. Jameson, “Inertial- 1998. (I used the ICAN-II spacecraft design, modified from cat D-T to cat H-B fuel, and scaled Electrostatic-Fusion Propulsion Spectrum: Air-Breathing to Interstellar Flight,” Journal of Propulsion and Power, down from 1 Hz to 0.2 Hz, and 302 GW to 2 GW.) FRC plasmoid v. 11. 1994. (Philo Farnsworth, the farm boy who invented the television, spent his last years in a lonely quest injection solenoid to attain break-even fusion in his ultra-cheap fusor devices. His ideas are enjoying a renaissance, thanks to H-B fusion reciprocating plasmoid reactor – The operation of Dr. Bussard, and working fusion reactors are making an appearance in high school science fairs. On the coaxial theory that the fusor is power-limited, I have scaled down Bussard’s 10 GW design to 360 MW.) this fusion engine is comparable to that of an internal combustion inlet engine. The fuel to be combusted is a 25 mg pellet of decaborane (H14B10), a solid at room temperature. This is magnetically Hula-Hoop radiator – By imparting heat to twin washer-shaped disks by converted into a hydrogen-boron plasmoid in a field-reversed direct conduction, the Hula-Hoop radiator avoids the diseconomies of configuration (FRC), and injected into a compression/burn scale that plague fluid radiators. Furthermore, they are robust against micrometeoroid strikes and hostile attack. The two hoop are 100-meters braided chamber. The compression stroke is driven by a piston sheath cermet hoop coupled to a 100 kHz axial magnetic field. This stroke ignites the FRC in diameter. They are made of braided cermets coated with graphite, and plasmoid at 300 keV. The sheath plasma forming the piston is plasmoid lubricated in a heat exchanger with tungsten disulfide (WS2). Radiating at lithium, water, or scooped atmosphere propellant. After being 1300 K, each has a specific area of 33 kg/m2 and 300 kWth/m2. compression coils This design is an Eklund original, published here for the first time. heat superheated, both the fusion products and the sheath propellant 100 kHz reciprocating source are expanded for thrust or energy in a magnetic nozzle. Electrical MHD energy for the compression is picked up via MHD coils in the exhaust. coils The high energy density, direct propellant coupling, magnetic MHD fan cruciform filament radiator direct (one of seven sets shown) insulation, and low fusion gain allow for a vastly lighter engine than converter magnetic e-beam condenser other magnetically-confined fusion systems such as spherical nozzle heating Tokamaks. With open-cycle cooling and an air scoop, the thrust propellant FRM to weight ratio can be above unity, allowing a ramjet version to enter orbit sheath choke tandem cell mirror from the Earth’s surface. Although the H-B reaction is aneutronic, collisions cells 3He-D neutral between the ions and electrons lose half the energy to bremsstrahlung X-rays. injection/heating end coil The sheath, acting as open-cycle coolant, intercepts many of these X-rays, magnetic allowing a thermal efficiency of 85%. At 100 kHz and 2.5 kg/sec, 3 GWth is 3He-D Fusion Mirror Cell Reactor/Thruster nozzle generated with an overall efficiency of 65%. John Slough, “Earth to Orbit based on a Reciprocating Plasma Liner, Compression of Fusion Plasmoids,” University of Washington, 2007. 17 Impact mold sinter refinery – Sintering is a method for making feed stock solar The methane and oxygen produced can be used to power chemical rockets for the radiation objects by heating powdered material below its melting point until ascent stages. The CH4/O2 fuel, with a specific impulse of 380 sec, is the the particles adhere to each other. The impact mold process powder highest-performing space-storable chemical propellant that is ISRU capable. In sequentially blows metal grains into an impact die. As these grains centripetally the absence of an atmosphere, ISRU units can produce H O, H , and CO by sorted powder 2 2 accumulate on the developing workpiece, they are sintered by the controller steam-heating crushed carbonaceous asteroidal material to 1300 K in a closed

energy of impact and coalesce by cooling. Insertable ceramic shields are injector vessel. In either case, the elemental carbon produced is used to make scan work used to create voids and internal patterns. As it is made, the part is surface nanotubes through electrophoretic techniques (the migration in solution of actively inspected by scanning electron microscopes or optical sensors scannable charged colloids). Nanotubes have higher electrophoretic mobilities than do which guide the beam to areas where the surface is rough, appears too powder particles, and move toward the negative electrode aligned along the electric beam porous, or has not adequately been filled. The parts then move to an field. C.R. Nichols, “Carbonaceous asteroids,” Bose Corporation, 1993. part inspection station for trimming by a high-energy laser, and assembly to part using an e-beam welder. finishing JTEC H2 thermoelectric generator – A heat engine uses a Stirling, Such an assembly line can produce at 180 kg/hr, with a specific power of 0.5 MW/(ton/hr of Brayton, or Rankine cycle operating between a hot source and a cold product), and 5 ton of machinery/(ton/hr of product). The parts will typically be made of source. This is a mechanical device, using circulating fluids and pistons nickel/carbon fibers sintered with minor amounts of aluminum. The reaction creating or turbines to express its energy, typically with about 30% efficiency. In

contrast, the JTEC (Johnson Thermo-Electrochemical Converter) is all PCM nickel aluminide is highly exothermic, so much of the heat of reaction supplies the heat solid-state, generating electricity without moving parts at efficiencies of sintering energy required. A part made of nickel aluminide has a stiffness and a strength H2 about 60%. The JTEC generator utilizes the electro-chemical potential to weight ratio far superior to titanium, for temperatures well over 770 K. Iron-nickel hot hi-pressure fines can also be impact mold sintered. George Hansen, Metal Matrix Composites Company, 2008. of hydrogen pressure applied across a proton conductive membrane (PCM). On the high-pressure side of the PCM, hydrogen gas is membrane electrode

In-core thermionic generator - A thermionic conversion system may be oxidized resulting in the creation of protons and electrons. The stacks heat radiator conceived as an "electron boiler". Electrons are thermally boiled off a pressure differential forces protons through the membrane causing the heat exchanger heated emitter cathode, and collected on an anode surface, delivering electrodes to conduct electrons through an external load. On the radiators DC electrical power to an external load. In-core thermionic systems are low-pressure side, the protons are reduced with the electrons to reform composed of converters which are directly attached to individual fuel hydrogen gas. The PCM and a pair of electrodes form a membrane H2 elements within the reactor core (fast fission or fusion). The anode is electrode stack similar to those used in fuel cells. The JTEC uses PCM cooled by a loop which circulates a liquid metal coolant to an external two of these, one coupled to a high temperature (up to 1400 K) heat source cold hi-pressure radiator. The baseline system uses single-layer BaCs converters and and the other to a low temperature radiator. Hydrogen circulates within the collector anodes coated with SiC. Thermoelectric-electromagnetic (TEM) neutron engine between the two membrane electrode stacks via a counter flow shield pumps are used to pump the sodium to the radiators and back. When regenerative heat exchanger. Lonnie Johnson, www.johnsonems.com operating at a 1300 K emitter temperature, the cycle conversion thermionics nuclear core efficiencies are 15%, and the output is 125 MWe. Specific power Kuck mosquito robonaut - As icy dormant comets or D-type 40 tonne water including the sodium heat pipes is 2200 kg/MWe. T. Van Hagan of General Atomics, 1990. asteroids are warmed by the sun, they accumulate an outer bag anhydrous lag layer. An in-situ mining robonaut called the Kuck 220 kN Ion drive thruster –In space, an electrostatic particle accelerator is cathodeMg mosquito is designed to drill through this layer, inject steam, and chemical steam rocket effectively an electric rocket. The illustrated design uses a combination pump out the water in the core. Some of the water is electro- injector of microwaves and spinning magnets to ionize the propellant, lyzed for fuel for a small H2-O2 chemical engine. To gain a eliminating the need for electrodes, which are susceptible to erosion in anodes secure foothold, thermal lances melt into the substrate. The the ion stream. The propellant is any metal that can be easily ionized targeted bodies must have a cometary matrix of not less than magnets thermal and charge-separated. A suitable choice is magnesium, which is 30% ice. There is a danger of catastrophic fracture of the sub- well 50 kWe lance positive & anchor common in asteroids that were once part of the mantles of shattered Mg+ negative grids surface mantle layer due to the tensile forces generated by the screen rock splitter parent bodies, and which volatilizes out of regolith at the relatively low temperature of pressurization. Dave Kuck, “The Exploitation of Space Oases,” Princeton Conference on Space Manufacturing, Space Studies Institute, 1995. 1800 K. The ion drive accelerates magnesium ions using a negatively charged grid, and ice core neutralizes them as they exit. The grids are made of C-C, to reduce erosion. Since the stream is composed of ions that are mutually repelling, the propellant flow is limited to Lyman alpha trap reactor – This antimatter factory uses a 200 GeV lens low values proportional to the cross-sectional area of the acceleration region and the proton accelerator to smash a stack of multiple thin targets laser mirror

surrounded by wide angular arrays of multiple lenses with different + square root of the voltage gradient. Decoupling the acceleration from the extraction p e process into a two-stage system allows the voltage gradients to reach 30 kV without velocity acceptances. At a beam power of 0.2 MWj and a current + of 3.2 µamps, one in ten incident protons becomes an antiproton. amplifier vacuum-arcing, corresponding to exit velocities of 80-210 km/sec. A 60 MWe system e with a thrust of 1.5 kN utilizes a hexagonal array, 25 meters across, containing 361 The shower of antiprotons is entrained with positrons to form first p

accelerators. Frozen flow efficiencies are high (96%). To boost the acceleration atomic, then molecular, antihydrogen. This formation process is positron ring antiproton ring enhanced 100-fold by an optical laser traveling opposite to the laser ring (corresponding to the “open-cycle cooling” game rule), colloids are accelerated instead + beams of antiprotons and positrons, as shown in the illustration. e +

of ions. Colloids (charged sub-micron droplets of a conducting non-metallic fluid) are p e more massive than ions, allowing increased thrust at the expense of fuel economy. This antimatter beam is cooled by a radio frequency quadrupole H J. Beatty of Hughes, 1990. (RFQ) decelerator, trapped with Lyman alpha laser beams, and lens RFQ geostationary tickled into forming an iceball in a Lyman-alpha light trap. The Ionosphere lasing refinery – Sunlight maintains population inversions satellite iceball is grown into a charged microcrystal levitated by electrostatic forces. The temperature is kept below 1°K by lasers to keep sublimation pressure Lyman-! in the ionospheres of Venus, Mars, and (possibly) Saturn. If two mirror photon orbiting mirrors are arranged so the path between them intersects low. The energy of the unused exiting proton stream is recovered via MHD trap this portion of the atmosphere, the atmosphere itself can lase. The or uranium enrichment. The accelerator, powered by uranium fission,

system illustrated uses one mirror on an aerostat refinery floating in 1000 km produces 10 µg/year of antimatter. The gas-dynamic lasers use solar- the atmosphere, and the other on a satellite outside the atmosphere. Venus, pumped iodine gas. Robert L. Forward, “Antimatter Annihilation Propulsion”, 1985. laser interactive Marsregion solar The laser interactive region is 1000 km of atmosphere, comprising or Saturn radiation perhaps a grams worth of excited molecules. This is enough for 5 kJ not to Mag sail thruster – At 1 AU, the solar wind comprises several million scale laser pulses at 8 kHz (average power 40 MW). This is a significant protons per cubic meter, spiraling away from the sun at 400 to 600 ionosphere aerostat km/sec (256 µwatts/m2). When such charged particles move power level, for propulsion, refining, and weapons purposes. refinery spinning D. Deming and M. Mumma, "Modeling of the 10 micrometer natural laser emission through a magnetic field formed by the mag sail, a tremendous loop disk sail from the mesospheres of Mars and Venus", NASA/Goddard,1983. CO2 of wire some 2 km across, they are deflected. An unloaded mag sail methane booster this size has a thrust of 100 N (at 1 AU) and a mass of 20 tonnes. The ISRU Sabatier refinery - The Sabatier reactor uses In-Situ H2 Sabatier chamber wire is superconducting whisker, at 10 kg/km, connected to a central Resource Utilization (ISRU) to create a closed hydrogen and fuel tank rotation (CH4) bus and payload via shroud lines. The loop requires multi-layer oxygen cycle for life support on planets with CO2 atmospheres con- CH4 payload denser insulation and reflective coatings to maintain its superconducting such as Mars or Venus. It contains two chambers, one for temperature of 77 K. Because the sail area is a massless magnetic H2O photonic mixing and the other for storing a nickel catalyst. When charged O laser H2 2 oxidizer field, a mag sail has a superior thrust/weight ratio than photon sails. thruster with hydrogen and atmospheric carbon dioxide, it produces electrolysis (LO ) shielded 2 Just as with photon sails, lateral motion is possible by orienting the mirrors super- water and methane. (The similar Bosch reactor uses an iron conducting turbine sail at an angle to the thrusting medium. A mag sail also develops mag loop catalyst to produce elemental carbon and water.) A condenser thrust from planetary and solar magnetospheres, which decrease as the fourth separates the water vapor from the reaction products. This injector combustion power of the distance from the magnetosphere source. Field strength is typically condenser is a simple pipe with outlets on the bottom to collect chamber 10 µT in Earth’s magnetosphere, or less in the solar magnetosphere. The mag water; natural convection on the surface of the pipe is enough sail illustrated is augmented by a spinning disk photon sail attached to its staying to carry out the necessary heat exchange. Electrolysis of the lines. It is maneuvered using photonic laser thrusters (propellantless thrust water recovers the hydrogen for reuse. NASA 2007. 18 derived from the bouncing of laser photons between two mirrors). Zubrin 1988. helium liquefaction Magma electrolysis refinery – This refining unit melts regolith with O2 Metastable helium thruster – Metastable helium is the solar energy, and passes electricity through the melt. This liberates filter electronically excited state of the helium atom, easily formed by polarized electron laser beam *

oxygen at one electrode, and reduces the material to a lower a 24 keV electron beam in liquid helium. If the spin-orbit decay 2 Na2O ZnO oxidation state at the other. A flux material is used to reduce the K O absorbs is suppressed by a coherent laser pump, its theoretical lifetime 2 H S melting temperature of the regolith to around 1600 K. An 2 would be eight years (as ferromagnetic solid He*2 with a melting anodes

80-tonne magma electrolysis unit with a throughput of 5000 temperature of 600 K). Spin-aligned solid metastable helium metastable He tonnes of regolith per year and a 3.5 MW power source + + + + cera- could be a useful, if touchy, high thrust chemical fuel with a e Magma Layer mics ignition produces 2000 tonnes of ceramic and silicon blocks or theoretical specific impulse of 3.2 ksec. gun heatshields, 1000 tonnes of oxygen, and hundreds of tonnes Fe-Si J.S. Zmuidzinas, "Stabilization of He2(a 3Sigmau+) in Liquid Helium by Optical of iron, magnesium, and silicon. The silicon can be zone- Pumping," unpublished 1976, courtesy Dr. Robert Forward. magnetic refined to high purity for solar panels. Zone-refining does not carbon nozzle require chemicals that must be upported from Earth and will cathode MHD open cycle generator – Magnetohydrodynamics (abbreviated be done more easily in the low gravity and vacuum of space than on Earth MHD) is the control of plasmas using magnetic fields. A MHD electric generator has the advantages of high direct energy conversion plasma (where it must be done in inert gas-filled chambers and rods can't be too output is massive lest they fall apart at the molten zone). The molten materials are efficiencies (90%), no moving parts, and instant turn-on. Installed on exhausted processed into their final form by use of a laser stereolith (a kind of 3-D printer the output of a rocket nozzle or vapor core reactor, it magnetically B-field that uses CAD software to create objects by hardening the materials one layer expands and cools the exhausted plasma, extracting electrons with a large grounded collector plate. MHD can also convert laser energy at a time). David Dietzler, www.moonminer.com

fusion voltage plasma into electricity. For the open-cycle design shown, an expander reducer 77 K spreads out into a fan shape with a radius of many meters. The Magnetic nozzle thruster – High specific impulse cryogenic thermodynamic rockets benefit from a nozzle that radiator positive ions (at energies in the region of 400 kilovolts for fusion end is not limited by the melting point of its material. 25 T loss plasmas) are collected on a series of high voltage electrodes, resulting in the direct transfer of kinetic energy to a direct current. deceleration voltage Magnetic nozzles direct the exhausted flow of ions super- & collection conducting 5 T The electrodes must be cleaned to prevent build-up of conductive electrodes multiplier or a conductive plasma by use of magnetic fields coils deposits that can cause shorts. The process is reversible, with an charge instead of walls made of solid materials (see de separation Laval nozzle). If superconducting coils are used, input of electricity the fuel economy of the rocket exhaust (such as for DC these must be thermally shielded to remain in the chemical rockets or arcjets) can be doubled. Room-temperature superconducting range. The design illustrated superconducting magnets with a high current density create a hot plasma crossed field region (4 T) that accelerates the plasma with Lorentz input operates at a throat magnetic field strength of 25 T 1.5 T and a nozzle efficiency of 86%. example forces. Because of material limits, the duct temperature is limited to 2500 K. The plasma ion path is usually seeded with an alkali metal (e.g. magnesium) for conductivity, which must be recovered and recycled from the effluent stream. The net power density is 350 kg/MW . Marangoni flow radiator – In zero-g, a surface tension e cold Samim Anghaie, “Development of Liquid-Vapor Core Reactors with MHD Generator for Space Power and gradient can create a heat pump with no moving parts, motion Propulsion Applications,” University of Florida, 2002. or drive micro-refining processes. This phenomena, of surface bubble heat called Marangoni flow, moves fluid from an area of high source Microbial fuel cell generator – Bioengineered “organic-electronic” crops grown in space surface tension to one of low surface tension. Bubbles Marangoni transfer organic material through their roots into the sediment, a process called 2 convection operating at 1300 K have a specific area of 24 kg/m . cell rhizodeposition. A microbial fuel cell (MFC) uses bacteria as a catalyst to convert the G. Harry Stine, “The Third Industrial Revolution,” 1979. chemical energy of this sediment directly into electricity. The bacteria in the anaerobic sediment will use the MFC anode as an insoluble electron acceptor. Using nano-wires, Mass driver thruster – An electrodynamic traveling-wave accelerator the anode collects 95% of the electrons originating from the microbial metabolism. The can be used as either a thruster or a payload launcher. The reaction protons flow through a proton or cation exchange membrane to the cathode, where they mass or payload is loaded into a lightweight bucket banded by a are reduced with oxygen into water. For rhizodeposition feeding rates of 0.3 kg/liter/day, pair of superconducting loops acting as armatures of a linear-electric MFCs achieve a kilowatt per square meter of electrode surface. This power is stored in guideway. The thruster illustrated accelerates the bucket at 75,000 “living capacitors”. Entrained nanotubes allow bucket + 36 kg H2O O e- gee's, utilizing 7 GJ of electromagnetic energy stored inductively in reaction mass high surface areas and nearly instantaneous 2 + + crop superconducting coils. The trackway length is 390 meters. One 36kg of charging without degradation. The dielectric is water H cathode H e- plant reaction mass is ejected each minute at 15 km/sec. The bucket is decelerated whisker nMOS, with vapor-deposited gold leads. PEM e- anode e- and recovered. Cryogenic 77°K radiators cool the superconductors. Up to 4 GJ of solar energy are stored in 20,000 bacterium NADH NAD NAD+ A mass-driver optimized for materials transport rather than for propulsion uses a cells, each at 390 K and 30V. A plot 320 meters glucose sediment higher ratio of payload mass to bucket mass. With a 54% duty cycle, this across (8 hectares) at 1 AU generates 60 MWe. CO2 system can launch 10 kt/yr of factory products. Coupled with a pointing accuracy in the tens of microradians, this can launch payloads or projectiles to Microtube array radiator – Nanofacturing techniques can fabricate large, leak targets millions of kilometers distant. A terrestrial mass driver running up the parallel arrays of microtubes for high performance radiators. The radiating detection side of an equatorial mountain can launch payloads at the Earth escape surface comprises a heavily-oxidized, metal alloy with a 100 nm film of microtubes velocity (11 km/sec). Imparted with a launch energy of 76 GJ, a one tonne corrosion resistant, refractory platinum alloy deposited on it. The working payload the size and shape of a telephone pole with a carbon cap would burn fluid is hydrogen, which has low pumping losses and the highest specific up only 3% of its mass and lose only 20% of its energy on its way to solar or heat of all materials. This fluid is circulated at 0.1 to 1 MPa through the H Earth orbit. Gerard K. O’Neill, “The High Frontier: Human Colonies in Space,” 1977. microtubes, and the heat radiates through the thin (0.2 mm) walls. This 2 H2O allows a specific area of 34 kg/m2, including the hydrogen. The rejection MET steamer robonaut - Microwaves can serve either mining or temperature for titanium alloy tubes is from 200 K up to 1000 K, if a high heat source thrusting functions. In their mining capacity, they are focussed B field temperature barrier against hydrogen diffusion is used. High speed leak to create “hot spots” inside rock, which expands and spalls its (AC) detection capability and isolating valves under independent microprocessor outer layers. Ice and minerals such as carbonaceous reducer control provide puncture survivability. F. David Doty, Gregory Hosford and Jonathan mode) cavity E field 1 and ilmenite have high microwave absorbing properties. In their 01 B. Spitzmesser,"The Microtube-Strip Heat Exchanger," 1990. H2 (AC) MET discharge tube microwave electrothermal thruster (MET) capacity, a (TM detail of microwave-sustained plasma superheats water propellant, Mini-Magnetosphere rf Paul trap reactor – The natural environment rf Paul trap micro-

which is expanded for thrust in a magnetic nozzle. discharge of space can be used as a low energy accumulator to antimatter and wave laser Because this design has no electrodes, water is the preferred probe other exotic particles. This device turns a spacecraft into a Bussard chirping B field cooling propellant (the oxygen atoms in a steam discharge would (DC) ramjet, (albeit one that scoops fuel rather than propellant, a much nozzle quickly dissolve electrodes). A discharge source temperature magnetic simpler task). The “scoop”, a huge (100 km) magnetic bubble called solenoid of 8000 K, augmented by rapid hydrogen-oxygen recombina- a “mini-magnetosphere”, is inflated with conductive ionized gas or photovoltaics tion in the nozzle, achieves 900 seconds of specific impulse. plasma. Field lines are generated by onboard solenoids, powered by Vortex stabilization produces a well-defined axisymmetric flow. However, the 3 kW photovoltaics. A reservoir of helium replenishes ions that leak specific impulse is ultimately limited by the maximum temperature (~ 2000 K) from the plasma. The field lines of the mini-magnetosphere direct that can be sustained by the thruster walls. The illustration shows a solar wind onto a heavy metal target. The resulting spray of photons microwave plasma discharge created by tuning the TM(011) mode for and particle-antiparticle pairs contain a small fraction (<5%) of solar impedance-matched operation. This concentrates the most intense electric proton-antiproton pairs, as well as other exotics. These are magnetically wind fields along the cavity axis, placing 95% of the energy into the propellant, with focused, debunched and cooled using laser chirping and radio frequency (rf) fields, and less than 5% lost into the discharge tube walls. Regenerative water cooling is stored along with positrons in a low energy rf Paul trap. Neutral antimatter hydrogen is used throughout. For pressures of 45 atm, each unit can produce 30 N of condensed as electrostatically-suspended ice pellets. A few micrograms per year of thrust. The thrust array contains 400 such units, at 50 kg each. antimatter ice is produced, at densities approaching 1023 atoms/cc. The mini-magneto- John L. Power and Randall A. Chapman, “Development of a High Power Microwave Thruster, sphere can also act as a sail, deriving thrust from the solar winds. Robert M. Zubrin, "The use with a Magnetic Nozzle, for Space Applications.” Lewis Research Center, 1989. 19 of magnetic sails to escape from low earth orbit", Journal of the British Interplanetary Society, 1993. 6 Mirror steamer thruster – Water is an attractive volumetric n- Li microfission thruster – The minimum explosive yield for exotic beam receiver initiator absorber for infrared laser propulsion. Diatomic species formed & concentrator fission bombs is about a quarter kiloton. Thus, rockets that fly bomb bottle from the disassociation of water such as OH are present at using atomic explosions, such as Project Orion, require huge storage focusing temperatures as high as 5000 K, and can be rotationally excited mirror shock absorbers. The pulse energy can be brought down to B-field by a free electron laser operating in the far infrared. The OH H2 microfission levels by the use of exotic particles. A n-6Li 6 molecules then transfer their energy to a stream of hydrogen window microfission thruster brings the lithium isotope Li to spontane- magnetic plenum coils propellant in a thermodynamic rocket nozzle by relaxation ous microfission by interaction with particles with very large magnetic collisions. Beamed heat can also be added by a blackbody cavity reaction cross sections such as ultracold neutrons. No “critical nozzle

supersonic solar or laser beam absorber. This heat exchanger is a series of concentric cylinders, aerodynamic mass” is required. This clean reaction produces only charged bomb window made of hafnium carbide (HfC). Focused sunlight or lasers particles (T and He), each at about 2 MeV. The system illustrated uses a 5-meter absorption passes through the outermost porous disk, and is absorbed in the chamber magnetic nozzle to transfer the microexplosion energy to the vehicle. This cavity. Heat is transferred to the propellant by the hot HfC without A 115m concentrator magnetic impulse transfer is borrowed from the MagOrion concept (combination the need for propellant seeding. The specific impulse is obtains 15 MWth at 3 kN. of Orion and the magnetic sail). A fuel reaction rate of 60 mg/sec yields 3720 materials-limited to 1 ksec. MWth. At a pulse repetition rate of one 224 GJ (0.05 kT) detonation each F.G. Etheridge, “Solar Rocket System Concept Analysis,” Rockwell Space heat minute, the thrust is 12.8 kN at a 12 ksec specific impulse. A hydraulic fixture Systems Group. (I resized the Rockwell “Solar Moth” design for 3 kN thrust). sink oscillates at a tuned frequency to provide a constant acceleration to the Mo fin spacecraft. The combined frozen-flow and nozzle efficiencies are 21%, and the Mo/Li heat pipe radiator - A heat pipe quickly transfers heat from thermal efficiency is 96%. Ralph Ewig’s “Mini-magOrion” concept, modified for n-6Li fission, wick one point to another. Inside the sealed pipe, at the hot interface a http://www.andrews-space.com/images/videos/PAPERS/Pub-MMOJPLTalk.pdf two-phase working fluid turns to vapor and the gas naturally flows Section supersonic laser- Condenser nozzle sustained and condenses on the cold interface. The liquid is moved by plasma O’Meara LSP paralens generator – A laser can project a beam only so (LSP) capillary action through a wick back to the hot interface to far before it starts to spread. If a lens is inserted into the beam before evaporate again and repeat the cycle. For high temperature insulation plastic Section Adiabatic the spreading starts, then the energy in the beam is captured and Fresnel lens applications, the working fluid is often lithium, the soft silver-white Li vapor refocused to form a completely new beam. A lens is a gossamer element that is the lightest known metal. Molybdenum heat pipes structure that has the ability to focus electromagnetic radiation, containing lithium can operate at the white-hot temperatures of typically optical, infrared or microwave radiation. Illustrated is a 2 Section 1450 K, and transfer heat energy at 24 kW/cm , almost four times Evaporator 300-meter diameter O’Meara para-lens, consisting of alternating 2 solenoid that of the surface of the sun. The specific area is 150 kg/m . coils layers of nothing and Kapton plastic with a thickness chosen to add a David Poston, Institute for Space and Nuclear Power Studies at the University of heat getter pack 2 New Mexico, 2000 source Hf foils half-wave of phase to the laser light. Its parameter is 0.3 kg/m . By remote injecting the beam into a focusing rocket nozzle with a laser laser-beam superfluid powerplant MPD T-wave thruster – Impulsive electric rockets can accelerate propellant 3He plasma absorption efficiency of 90%, the specific impulse can be doubled. using magnetoplasmadynamic traveling waves (MPD T-waves). In the generator MHD coils in the nozzle generate DC electricity. Robert L. Forward, “Advanced Propulsion Concepts Study-Comparative Study of Solar Electric Propulsion design shown, superfluid magnetic helium-3 is accelerated using a and Laser Electric Propulsion,” 1975. megahertz pulsed system, in which a few hundred kiloamps of currents distributed superconducting briefly develop extremely high electromagnetic forces. The accelerator L-C circuits Palmer LSP aerosol lens generator – The lightest possible lens is sequentially trips a column of distributed superconducting L-C circuits that formed from a cloud of glass beads or aerosol droplets forming a 3-D shoves out the fluid with a magnetic piston. The propellant is micrograms pseudo-holographic Fresnel lens. If these beads have a highly of regolith dust entrained by the superfluid helium. The dust and helium are rf coil nonlinear index of refraction, they can be "organized" by a structured Fresnel structure interference kept from the walls by the inward radial Lorentz force, with an efficiency of laser beam that interacts with the nonlinear optical index of the beads pattern 81%. Each 125 J pulse requires a millifarad of total capacitance at a few to put forces on the beads that "trap" the beads into fresnel-zone-like hundred volts. Compared to ion drives, MPDs have good thrust densities three-dimensional holographic-grating lens structures. A typical bead and have no need for charge neutralization. However, they run hot and field is 300 meters across, with a parameter of 0.3 kg/m2 and a have electrodes that will erode over time. Moreover, small amounts of an transmission efficiency of 96%. The aerosol (vacu-sol?) lens can spatial light expensive superfluid medium are continually required. double the thrust of a rocket by focusing the laser light into modulator its supersonic exhaust stream in the nozzle. This creates a laser Nanobot robonaut – An army of nano regolith and ore scavenging sustained plasma (LSP), a 15,000 K stationary region which transfers incoming machines can be used for ore beneficiation. Molecular assemblers energy to the propellant via the reverse bremsstrahlung process. laser J. Palmer, "Aerosol Lens", J. Optical Society of America, Vol. 73, 1983. will use nano-structures much like enzymes to work with reactive cam molecules. Mechanical nanobots based on biomimetic soft A. Mertogul and H. Krier, “Two-temperature modeling of laser sustained hydrogen nanotechnology might actually incorporate biological protein plasmas,” Journal of Thermophysics and Heat Transfer, 1994. positive sorting H molecules (enzymes and ribosomes) to do some of their work. dee rotor He/Xe 2 He/Xe The nanobot illustrated uses legs driven by a harmonic drive. electrode Pebble bed fission reactor – This is a graphite-moderated, gas- cooled, nuclear reactor that uses spherical fuel elements called Harmonic drives use a pair of dislocations driven by a wave shield generator moving along the inner interface of a nanotube to "pebbles". The pebbles are tennis ball-sized and made of heat pipe electrostatic pyrolytic graphite (which acts as the moderator), interspersed deform a flexspine. Each rotation of the wave generator turns the motor reflector flexspine by a two-tooth increment relative to the surrounding drill with thousands of micro fuel particles of a fissile material (such as 235U). In the reactor illustrated, 360,000 pebbles are assembled spline. A sorting rotor selects for a desired atomic shape, such as negative dee rotor rim to create a 120 MWth reactor. The spaces between the pebbles helium 3. These features are driven by a nano-electrostatic motor, electrode electrode that operates on the principle of a Van der Graaff generator form the "piping" in the core for the coolant, either propellant or pebble inert He/Xe gas. This reactor is dual mode. It can operate either bed worked backwards. K. Eric Drexler, “Nanosystems,” 1992. as a generator for 60 MWe of electricity, or as a solid-core DTL & RFQ thruster using hydrogen propellant/coolant expelled at a specific Neutral beam robonaut – Beams of ions are easy to accelerate, but injectors nozzle they must be neutralized in space, otherwise their mutual electric source impulse of 1 ksec. When used as a thruster, it offers a slight repulsion would quickly diffuse the beam. (Also arcing would destroy increase in specific impulse but significant acceleration benefits

DTL the robonaut.) The ions accelerated are negatively charged, which lineac over traditional fission reactors. Moreover, the high temperatures (up to 1900 K) allow higher thermal efficiencies (up to 50%). The anti- obtains higher neutralization efficiency than positive ones. Neutral protons beams of hydrogen or deuterium, operating in a pulsed mode up to pebbles are removed as they are exhausted. Because of their trapped 800 MeV, pack more punch than lasers, which makes them useful in shell, they are not radioactive, so no dangerous waste is created. antiprotons mining or combat. They can also be injected into fusion reactors both cryomodule

superconducting focusing lineac to heat the plasma and replenish the burned fuel. If a plasma vortex is magnets Penning trap reactor – Exotic fuel, produced in a superconducting cavity supercollider, can be cooled by a radio frequency quadrupole (RFQ) needed, the neutral beam is introduced into the chamber off-axis. The cryogen cell design illustrated uses a Dudnikov high-brightness H- source with a transfer and stored and transported into space in liter-sized Penning trap radio-frequency quadrupole (RFQ) injector. A stage of resonance- thermos bottles. For instance, a thousand such traps, each E field B field coupled Alvarez drift-tube linacs (DTLs) boosts the beam to 85 MeV. weighing 80 kg, would hold 1017 antiprotons (140 ng), enough fuel A stage of super-conducting linacs increases the energy of the ions to cryomodule for a delta-v of 100 km/sec. Other fuels include metastable helium,

waveguide 600 MeV without unduly increasing the emittance of the beam (10-8 power coupler ultracold neutrons, and free radical hydrogen. A Penning trap uses injector

laser hi current m·rad). The beam is very precisely focused on a target by a magnetic neutralizer a combination of laser cooling and electromagnetic fields to store 14 beam-steering optics, and then passed through a laser photodetach- particles. Each is able to store more particles (10 ) then rf Paul liq He liq N2 beam jacket ment neutralizing cell in order to remove the extra electron. traps, and also does not use dynamic rf fields which can heat the tank trapped fuel. The Brillouin limiting factor for Penning traps is 1011 laser 20 antiprotons/cc. cooling force Photon heliogyro sail – A heliogyro is a photon sail consisting of Project Orion reactor – This fabled technology converts the blade multiple spinning blades. Its blades are rigidified by centrifugal angle impulses of small nuclear detonations into thrust. Each force and pitched to provide attitude control, much like a shaped-charge bomb has a mass of 230 kg (including

solar radiator helicopter. Although a spinning design does not need the radiation propellant) and a yield of a quarter kiloton (1 terajoule). The nuclear struts of a kite sail, the centrifugal loads generated must be fissile material is curium 245, with a critical mass of 4 kg, bomb 7.5 km storage carried by edge members in the blades. Moreover oscillations payload surrounded by a beryllium reflector. The soft X-rays, UV and & delivery are created when the sail’s attitude changes, which need to be blade plasma from the external detonation vaporize and compress restrained by transverse battens. Small sail panels prevent rotation the surrounding propellant to a gram per liter. This makes it wrinkling from the curvature in edge members between the highly opaque to the bomb energies at the temperatures pneumatic delivery battens. For these reasons, the heliogyro has no mass attained (67000 K). The propellant, a mixture of water, tube advantage over a kite sail, but it has the advantage of easier nitrogen, and hydrogen, interfaces with a pusher plate pusher shock deployment in space. The reference design at 1 AU generates 140 newtons “nozzle”, which can be either solid or magnetic. Shown is a plate absorbers maximum thrust from 4 banks of 48 blades each. Each blade has a dimension solid plate, which tapers to the edges (to maintain a constant of 8 x 7500 meters. This thrust is quite low (about 31 lbs), but its game net velocity of the plate given a greater momentum transfer in 1 TJ nuclear performance is comparable to an electric rocket since its impulse is imparted the center). Pressure on the plate reaches 690 MPa in the center. detonation over a full year rather than a few days. The sail film is 1 µm thick with reflective The impulse shock is absorbed by a set of pneumatic “tires”, followed by and emissive coatings. Each bank is fixed to a hub so the members co-rotate. gas-filled pistons detuned to the 56 Hz detonation frequency. The shock The combined film masses 7 tonnes alone, and with the supporting cables plate system becomes a useful shield if pointed towards the enemy. The masses 40 tonnes. amount of blast energy utilized for thrust is 7%, and the amount of pulse Scaled up from the JPL Halley Rendezvous design: Jerome Wright, “Space Sailing”, 1992. mass that intercepts the plate is 39%. A 56 TWth design optimized for 1TJ bombs achieves a specific impulse of 2 ksec and a thrust of 2.2 MN. Photon kite sail – The simplest way to hold a sail out to catch Ted Taylor’s classic design, optimized for low yield bombs and 2 ksec specific impulse: George sunlight is to use a rigid structure, much like a kite. The columns solar Dyson, Henry Holt and Company, “Project Orion”, 2002. and beams of such a structure form a three-axis stabilization, radiation payload electrically initial Pulsed plasmoid thruster – A plasmoid is a coherent torus- conducting plasmoid so-named because all three dimensions are rigidly supported. torus Kite sails are easier to maneuver than sails that support shaped structure of plasma and magnetic fields. An example nozzle themselves by spinning. By tilting the sail so that the light from nature is “Kugelblitz” (ball lightning). (One of my mentors, pressure slows the vessel down in its solar orbit will cause an Dr. Roger C. Jones of the University of Arizona, has worked out the physics of this.) A plasmoid rocket creates a torus of laser PV inward spiral towards the sun. Tilting the opposite way will cause plasmoid

an outward spiral. The kite sail shown has a has a mast, four ball lightning by directing a mega-amp of current onto the torus 4 km 4 booms, and stays supporting a square sail 4 km to a side. At propellant. Almost any sort of propellant will work. The 93% reflectance, it develops a maximum thrust of 182 newtons plasmoid is expanded down a diverging electrically conduct- laser at 1 AU. Control is provided by 4 steering vanes of 20,000 m2 ing nozzle. Magnetic and thermal energies are converted to steering area each. The unloaded mass is 16,000 kg and the unloaded vane directed kinetic energy by the interaction of the plasmoid with the image sail loading is 0.5 g/m2. currents it generates in the nozzle. Ionization losses are a small fraction of the The film is 300 nm aluminum. Its microstructure is formed by DNA scaffolding, total energy; the frozen flow efficiency is 90%. Unlike other electric rockets, a which is then coated with aluminum and the DNA baked off. This leaves holes plasmoid thruster requires no electrodes (which are susceptible to erosion) the size of the wavelength of visible light, which makes the film lighter. The and its power can be scaled up simply by increasing the pulse rate. The perforated film is thermally limited to 600K, and cannot operate in an Earth design illustrated has a 50-meter diameter structure that does quadruple orbit lower than 1000 km due to air drag. Its thrust can augmented by the duty as a nozzle, laser focuser, high gain antenna, and radiator. Laser power illumination of the 60 MW laser beam which is standard in this game. (60 MW) is directed onto gap photovoltaics to charge the ultracapacitor bank Operating at 50 Hz, this beam boils off water coolant replenished through used to generate the drive pulses. R. Bourque, General Atomics, 1990. capillary action in the perforated film. Tiny piezoelectric robot sailmakers repair Quantum cascade laser robonaut – Mineral grains blasted Ti/Pt/Au contact-pad “Buckyball” ablated portions of the sail using vapor-deposited aluminum. fullerene Twice the size of Garvey’s “Large Square Rigged Clipper Sail”, and adding the perforation feature: from asteroidal ores can be photoelectrically-charged with J. M. Garvey, "Space station options for constructing advanced solar sails capable of multiple solid-state IR lasers such as quantum cascade lasers. Once mars missions", AIAA Paper 87-1902, AIAA/SAE/ASME 23rd Joint Propulsion Conference,1987. photoelectrically separated, the ores are readily processed electrically, thermally and chemically to extract metals and – Microwaves beamed from HR mirror Photon tether rectenna generator (6 in formation) interferometric oxygen. The quantum cascade laser shown uses carbon ranging & 10 kW mid-IR a remote satellite are efficiently converted into DC power by photon thruster buckytubes as the gain medium in a Fabry-Perot resonator. laser Fabry-Perot resonator using a special antenna called a rectenna. This assemblage of 2 m wavelength The layers of buckytubes form a series of quantum wells, substrate n - InP dipole antennas is connected to a network of rectifiers and down which electrons cascade. Each electron tumbles down filters that rectify AC at 30 GHz into DC power. The rectifiers thousands of wells, producing a photon at each step. This electronic waterfall are nanotube Schottky barrier diodes, at 90% conversion greatly boosts wall plug efficiency (30%), enabling quantum cascade lasers to efficiency. Because of the attenuation of the beam at range, mesh emit gigawatts of peak power in pulsed operation and tens of megawatts in the rectenna must be very large. To achieve a specific power continuous wave. The wavelength is altered by modifying the buckytube of 700 kg/MW, the diodes are mounted on a thin etched film temperature. For long range work, a set of laser expanders are used for to condenser of Kapton stretched between tethers. The tethers are held in precise beam pointing and to decrease the spot size at great distances. microwave tension by a formation flight of ultra-stable photon thrusters, radiation each 10 km from each other. These small (10 W) diode-pump Rankine MHD generator - As contrasted to the Brayton cycle, the lasers have a retargeting slewing accuracy of 1 micro-arcsec. 10 km Rankine heat engine cycle uses a working fluid that changes phase. B The nanothrust is amplified 20,000 X (to 1.34 mN) by intracavity CW laser beam This yields lower cycle temperature ratios, and thus lower masses bouncing the intracavity CW beam between high relectance 4mm kevlar and higher efficiencies (22%). Rankine MHD is a closed-cycle tether gas mirrors. Robert Cassanova, “Photon Tether Formation Flight,” 2006. version of the MHD generator. Magnetohydrodynamic (MHD) vapor core BeO fuel reactor helicon conversion systems produce electrical power the same way as antenna BeO Ponderomotive VASIMR thruster – The variable-specific-impulse rf power conventional turbine generators, except that the rotating magnet is amplifiers H2 magnetoplasma rocket (VASIMR) has two unique features: the replaced by a conductive ionized plasma, which passes through a B ICRF removal of the anode and cathode electrodes (which greatly antennas channel surrounded by a magnetic field. This generates power proportionate increases its lifetime compared to other electric rockets) and the ion to the channel volume, plasma velocity, and magnetic field strength. The cyclotron ability to throttle the engine, exchanging thrust for specific impulse. resonance ultrahigh temperature system shown uses a disk MHD generator (Hall type with A VASIMR uses low gear to climb out of planetary orbit, and high power radiator amplifier 4T magnetic field) surrounding the output stream of a reactor. For a vapor-core gear for interplanetary cruise. Other advantages include efficient fission reactor, the working fluid is uranium tetrafluoride (UF4) plus KF at 4000 K resonance heating (80%), and a low current, high voltage power aft power and 40 atm. After being expanded to 0.08 atm in the MHD diffuser, the UF4 conditioner, which saves mass. Propellant (typically hydrogen, conditioners H2 pump /KF is condensed, separated in radiators operating at 2100 K, and recycled. although many other volatiles can be used) is first ionized by helicon Losses are proportionate to channel area. The nuclear core normally remains at waves and then transferred to a second magnetic chamber where it a subcritical fuel density with a neutron flux of 1015 n/cm2-sec. The output is accelerated to ten million degrees K by an oscillating electric and plasma has a nuclear-enhanced electric conductivity of 60 mho/m. If a pulse of magnetic fields, also known as the ponderomotive force. A hybrid power is needed (for pulsed lasers or electric engines), the active volume of the two-stage magnetic nozzle converts the spiraling motion into axial core is decreased to criticality, using pulsed MHD magneto-induction. The thrust at 97% efficiency. Franklin Chang-Diaz, et al., “The Physics and system has a power of specific power of 1.5 ton/MWe. Engineering of the VASIMR Engine,” AIAA conference paper 2000-3756, 2000. Samim Anghaie, “Development of Liquid-Vapor Core Reactors with MHD Generator for Space 21 Power and Propulsion Applications,” University of Florida, 2002. C - C Salt-cooled reflux tube radiator –In contrast to a heat pipe, that fins Stirling engine generator - The Stirling cycle uses a closed-cycle displacer heat

uses capillary action to return the working fluid, a reflux tube uses condensor reciprocating engine and a high-pressure single-phase gaseous regenerator centrifugal acceleration. This design is more survivable than heat woven C - C working fluid, often hydrogen or helium. The fluid may be heated by pipes, especially when overwrapped with a high-temperature fabric surface solar or nuclear energy. The engine is designed to compress the piston carbon-carbon composite fabric. Unlike metals, the strength of working fluid in the colder side of the engine and expand it in the radiator these composites increases up to temperatures of ~2300K. hot side, resulting in a net conversion of heat into rotary motion. However, they degrade when subjected to high radiation levels. The free piston Stirling converter illustrated is optimal for space The working fluid is molten fluoride salts, the only coolant (other Ti liner applications due to the absence of wear mechanisms. A Stirling centrifugal salt return than noble gases) compatible with carbon-based materials. engine heated by a solar mirror 425 meters in diameter at 1 AU Radiating at 1100 K, this radiator has a specific area of 75 kg/m2. produces an output of 60 MWe of alternating current. If carbon- Charles W. Forsberg, Oak Ridge National Laboratory, Proceedings of the Space carbon composites are used, the hot side of the Stirling cycle can Nuclear Conference 2005, San Diego, California, June 5-9, 2005. reach temperatures of 2000 K, with a thermodynamic efficiency of evaporator 30%. This efficiency is superior to all other heat engines. Salt-water Zubrin thruster – The illustration shows the vision of heat source Robert Zubrin: a rocket riding on a continuous controlled nuclear Superconducting adductor generator – Energy can explosion just aft of a nozzle/reaction chamber. The propellant is be stored inductively in the magnetic field of coils adductor heat shield water, containing dissolved salts of fissile uranium or plutonium. torus chilled to superconducting temperatures. A toroidal current O O O These fuel-salts are stored in a tank made from capillary tubes of 2 2 2 lead

/ H / H / H geometry lessens the external magnetic forces and C C C C 4 4 4

4 4 4 4 port B B B B boron carbonate, a strong structural material that strongly absorbs UBr UBr UBr reduces the size of the mechanical support needed. thermal neutrons, preventing the fission chain reaction that would A 25 tonne adductor with a volume of 150 cubic otherwise occur. To start the engine, the salt-water is pumped from H2O UBr4 / H2O H2O meters stores 6 GJ in a magnetic field of 10 T. Its the fuel tank into an absorber-free cylindrical nozzle. The salt-water coolant parameter is 40 MJ/m3 at 60 MWe. Kamiyama, 1994. port velocity is adjusted as it exits the tank so that the thermal neutron flux peaks sharply in the water-cooled nozzle. At critical mass critical Thermophotovoltaic generator – A solar thermophotovoltaic mass Photovoltaics (around 50 kg of salt water), the continuous nuclear explosion detonation (TPV) system includes both a photon element and a heat GaSb layer produces 427 GWth, obtaining a thrust of 8600 kN and a element, so it can run off of both light and heat. The photon InGaAsSb specific impulse of 8 ksec at a thermal efficiency of 99.8% element includes a filtered blackbody-based converter, layer (with open-cycle cooling). Overall efficiency is 80%. bandpass/infrared (IR) reflector filters, and monolithic Robert Zubrin, "Nuclear Salt Water Rockets: High Thrust at 10,000 sec ISP," two-junction two-terminal TPV converters: GaSb (top Journal of the British Interplanetary Society 44, 1991. cell)/InGaAsSb (bottom cell). The heat element has three SiGe layer diamond nanofactured layers: silicon germanium (SiGe), lead radiator PbTe layer Solar carbothermal refinery – Although aluminum is Bi2Te3 layer Al2O3 tellurium (PbTe), and bismuth telluride (Bi2Te3). C common in space, it stubbornly resists refining from its oxide solar When equipped at 1 AU with a lightweight solar concentrator 300 meters in Thermoelectrics Al3O2. It can be reduced by a solar carbothermal process, radiation power heliostat diameter, solar TPV generates 60 MWe of DC power. With an 1800 K heat using carbon as the reducing agent and solar energy. tower mirrors source, both high cascade efficiency (62%) and high output power density Compared to carbo-chlorination, this process needs no (about 20 kW/m2) are realized. Other parameters are 1 kg/m2 specific area, and chlorine, which is hard to obtain in space. Furthermore, the 1400 kg/MWe specific power. Sang Choi, Nano-BEAMS Lab, NASA Langley Research use of solar heat instead of electrolysis allows higher Al2O3 + 3 C + solar heat 2 Al + 3 CO Center, 2003. heat efficiency and less power conditioning. The solar energy sink

i fin

T required is 0.121 GJ/kg Al. Ti/K heat pipe radiator – A Rankine evaporation-condensation The aluminum and oxygen produced can be used to fuel Al-O2 chemical LO2 cycle heat pipe uses metal vapor as the coolant, which is boosters, which burn fine sintered aluminum dust in the presence of liquid sintered liquefied as it passes through a heat exchanger connected to Al from Section oxygen (LO2). Unlike pure solid rockets, hybrid rockets (using a solid fuel power the radiator. A liquid metal near the liquid/vapor transition is Condenser and liquid oxidizer) can be throttled and restarted. The combustion of tower able to radiate heat at a nearly constant temperature. The aluminum obtains 3.6 million joules per kilogram. At 77% propulsion pipe is made from SiC-reinforced titanium (Ti) or superalloy

efficiency, the thrust is 290 kN with a specific impulse of 285 seconds. operating at up to 1100 K, and the working fluid is insulation Section The mass ratio for boosting off or onto Luna using an Al-O2 rocket is 2.3. potassium (K). The pipe is covered with a lightweight Adiabatic In other words, over twice as much as much fuel as payload is needed. K vapor thermally-conductive carbon foam, which protects the pipe wick Gustafson, White, and Fidler of ORBITECTM, 2010. CsXe plasma from space debris and transfers heat to the radiating fins. The total specific area is 100 kg/m2. MHD power Evaporator Section Solar-pumped MHD excimer laser robonaut – Lasers which duct are pumped by solar heat, without the need to convert it to amplifier heat oscillator Tin droplet radiator – Atomization increases the surface area source centrifugal electricity first, offer continuous high-power operation. Sunlight with which a fluid can lose heat. A hot working fluid sprayed Sn collector maintains an inverted population of short-lived pseudo- UV laser into space as fine streams of sub-millimeter drops readily loses output molecules called excimers, stable only in the excited state. 1000X sunlight heat by radiation. The cooled droplets are recaptured and pitot tube fluid They acquire supersonic speeds at 20 atm in a short-circuited recycled back into the heat exchanger. If tin (Sn) is used as a collection Faraday MHD duct, which forms the nozzle. This decouples lasant flow working fluid, the kilos per power radiated is minimized, using the electron and gas temperatures in its 1 T magnetic field. a heat rejection temperature of 1030 K and a total power in The system illustrated is a pulsed, solar-pumped, high-pressure CsXe excimer laser with a the megawatt range (comparable to the game value of heat Sn droplet sheet lasing volume of 40 liters and a temperature of 3000K. Each 4 kHz laser pulse is 15 KJ rejection of 120 MWth per therm). The low emissivity of liquid of 0.8944 µm UV light. Primary and secondary loops of superconducting MIC cables tin (0.043) is increased by mixing in carbon black, which Sn droplet generator and tethers secure a parabolic mirror film 540 meters in diameter, concentrating the distributes itself on the surface of the droplet. Evaporation sunlight a thousand times. The efficiency is 19%, requiring tons per second of gas flow losses are avoided by enclosing the radiator in a 1 µm plastic heat to remove heat from the lasant. This system does not need the economies of scale that film, which transmits radiation in the 2 to 20 µm (IR) range. heat exchanger a photovoltaic/microwave solar power satellite would entail. The receiving antenna can Such a film would continue to perform its function even if heat be small. It could beam its modest power (60 MW) to spacecraft, or to remote areas on repeatedly punctured by micrometeoroids. The illustration source Earth that need energy. A.J. Palmer, Hughes Research Laboratories, 1980. shows a triangular liquid droplet geometry. The collector, heat stainless located at the convergence point of the droplet sheet, employs SS/NaK pumped loop radiator –A Rankine evaporation-condensation steel radiator centrifugal force to capture the droplets. The total specific area cycle exchanges heat using a liquid metal as a coolant, which is is 6.4 kg/m2. K. Alan White, “Liquid Droplet Radiator Development vaporized as it passes through a heat exchanger connected to the Status,” Lewis Research Center, 1987. radiator. A liquid metal near the liquid/vapor transition is able to radiate heat at a nearly constant temperature. The usual medium is NaK volume If you enjoyed HIGH FRONTIER, try HARD VACUUM! sodium (Na) or sodium-potassium (NaK), which has a saturation accumulator temperature of nearly 1200 K at 1.05 atm. The plumbing is stainless NaK vapor The year is 1942, and a breakthrough has allowed the Axis steel (SS) tubes operating at up to 970 K with an emissivity of 0.9. heat and Allies to develop orbital spacecraft! An alternate The tube wall is half a millimeter thick to guard against meteoroid- heat exchanger reality game with rockets armed with 20mm cannon and puncture, and each pipe is an independent element so that a single heat source puncture does not cause overall system failure. Molecular beam .50 machine guns. See www.sierramadregames.com. cameras on long struts scan for meteoroid leaks, which are plugged with pop rivets installed by a tube crawler. Radiating at 970 K from AMERICAN MEGAFAUNA: Dinosaurs vs. Mammals in ancient America! both sides, this radiator has a specific area of 61 kg/m2, including fluid and heat exchanger. J. Calogeras, NASA/LeRC, 1990. 22 power H2 Tungsten resistojet robonaut – Tungsten (W) is the metal with the highest feed Vortex confined thruster – The hotter the core of a thermodynamic control rods melting point (3694 K). Electric-resistance elements made of tungsten may be rocket, the better its fuel economy. If it gets hot enough, the solid neutron used to smelt ore or heat propellant. An electrothermal rocket using core vaporizes. A vapor core rocket mixes vaporous propellant and reflector resistance heating is called a resistojet. To reduce ohmic losses, the heat W fuel together, and then separates the propellant out so it can be exchanger uses a high voltage (10 kV) low current (12.5 kiloamp) design. resistors expelled for thrust. Energy is efficiently transferred from fuel to

Hydrogen heated to 3500K obtains a specific impulse of 1 ksec. The frozen propellant by direct molecular collision, radiative heat, and direct radiator tangential flow efficiency (without hydrogen recombination) is 85%. Internal pressures reaction fragment deposition. The open-cycle arrangement fuel injectors are 0.1 MPa (1 atm). The specific power of the thruster is 260 kg/MWj and the illustrated accomplishes this by spinning the plasma mixture in a plasma thrust to weight ratio is 8 milli-g. Once arrived at a mining site, the tungsten vortex maintained by tangential injection of preheated propellant from vortex H2 elements are installed into a furnace wall of ceramic lego-blocks (produced the reactor walls. The denser material is held to the outside of the H2 in-situ from regolith by magma electrolysis). Tungsten resistance-heated cylindrical reactor vessel by centrifugal force. The fuel is subsequently cooled in a heat furnaces are essential in steel-making. They are used to sand-cast slabs of exchanger and recirculated for re-injection at the forward end of the reactor, while the iron from fines (magnetically-separated from regolith), refine iron into steel propellant is exhausted at high velocity. The plasma source can be fission, antimatter, or (using carbon imported from Type C asteroids), and remove silicon and sulfur fusion. For fission reactions, the outer annulus of the vortex is high-density liquid uranium impurities (using CaAl O flux roasted from lunar highland regolith). fuel, and the low-density propellant is bubbled through to the center attaining tempera- 2 4 high- voltage tures of up to 18500 K. A BeO moderator returns many reaction neutrons to the vortex. diamond-like lead 4-layer Ultracold neutron reactor – Neutrons are normally unstable carbon wall -metal shield Prompt feedback actuators maintain a critical fuel mass in spite of the turbulent flow of particles, with a half life of 12 minutes. When polarized and water or hydrogen propellant. Since the core has attained meltdown, reaction rates must ultra-cooled (using vibrators or turbines), they form a dineutron or be maintained by fuel density variation rather than with control rods or drums. For tetraneutron phase. These “molecules” are believed to be stable antimatter reactions, swirling liquid tungsten (about 4 cm thick) is used instead of and storable in total internal reflection bottles, lined with storage uranium, for absorbing anti-protons. For fusion reactions, it is the propellant that is diamond-like carbon as the neutron reflector. Ultracold neutrons cell cooler and higher in density, and thus it is the reacting fuel ball that resides at the center (UCN) have a huge quantum mechanical wavelength as a of the vortex. N. Diaz of INSPI, 1990. consequence of their slow movement (typically 0.4 µm @ 1 m/sec), plasma and thus can spontaneously initiate fission reactions such as Wakefield e-beam robonaut – An e-beam (beam of electrons) is a electrons n-235U or n-6Li. If the neutron source is a nuclear reactor, the RF coil to versatile tool. It can bore holes in solid rock (mining), impart velocity flip spins neutrons must be cooled from 2 MeV to 2 meV using a heavy UCN to reaction mass (rocketry), remove material in a computer numerical magnet polarizing water moderator, and then in a UCN turbine to 0.2 IeV. foil control cutter (finished part fabrication), or act as a laser initiator (free Robert L. Forward, “Alternate Propulsion Energy Sources”, 1983. electron laser). A wakefield electron accelerator uses a brief UF H2 6 (femtosecond) laser pulse to strip electrons from gas atoms and to beam wakefield VCR light bulb fission reactor – Most fission reactors avoid melt- shove them ahead. Other electrons entering the electron-depleted electrons ion channel down, but the vapor core reactor (VCR) runs so hot (25000 K) that zone create a repulsive electrostatic force. The initial tight grouping Ne

its core vaporizes. At this temperature, the vast majority of the a-silica window of electrons effectively surf on the electrostatic wave. Wakefield electromagnetic emissions are in the hard ultraviolet (UV) range. A Ne accelerators a few meters long exhibit the same acceleration as a field e-beam ionization “bulb” transparent to UV radiation, made of internally-cooled a-silica, Ne conventional rf accelerator kilometers in length. In a million-volt-plus bottles the fuel (gaseous uranium hexafluoride), while letting its fuel vortex electron beam the electrons are approaching lightspeed, so the term relativistic electron fission energy shine through. This energy can generate electricity Ne gaseous nuclear beam is appropriate. The wakefield can be used as an electrothermal rocket similar in using UV photovoltaics, or can heat seeded-hydrogen propellant, principle to the arcjet, but far less discriminating in its choice of propellant. Tajima 1979. which exits at a specific impulse of 2 ksec. The UF6 fuel, pressurized capa- bomb capa- & LMTL to 1000 atm, is prevented from condensing on the cooled wall by Z-pinch microfission generator – Electrodynamic zeta-pinch citors storage citors graphite moderator

the tangential injection of a neon “buffer” gas into a vortex. BeO moderator compression can be used to generate critical mass atomic bombs B-field at very low yields. These detonations can be used to generate 245 Von Neumann - Santa Claus machine refinery – The great impulsive power or thrust. Exotic fission material ( Cm) is utilized magnetic mathematician John Von Neumann (pronounced von noi-man) magnet to reduce the required compression ratio. The explosion of each nozzle heavy ions visualized a set of nanomechanical assemblers, operating on lighter ions low yield (335 GJ) atomic bomb energizes and vaporizes a set of Cm bomb permanent local energy sources and material inputs, which use sensors low mass transmission lines, used to pump either another high sacrificial transmission integrated by a central processing unit to perform a wide range collectors & current Z-pinch, or a bank of nanotube-enhanced ultracapacitors. LMTL ribbon line diamondoid of mechanosynthetic operations including mining. Assemblers synthesis Each bomb uses 40 grams of Cm fissile material and 60 grams of Be reflector material, E- are molecular machines capable of being programmed to build field with an aspect ratio of 5. A DT diode is used as a neutron emitter. The mylar transmis- stuff from raw materials such as those readily gleaned from gas inlet sion lines have a mass of 15 kg, and are replaced after each shot. The design illustrated carbonaceous regolith. Electrophoresis and magnetoplasma- ionization by is rated for a shot every 5.5 minutes, equivalent an output of 1000 MWth. If utilized for dynamic systems separate this regolith into its basic elements. electron beam thrust, this provides 7.7 kN at a specific impulse of 17 ksec. Ralph Ewig & Dana Andrews, The basic building blocks of Von Neumann machines are rods of “Mini-MagOrion Micro Fission Powered Orion Rocket”, Andrews Space & Technology, 2002. interlocked diamondoid fibers. (Diamondoid structures comprise a wide range Persons interviewed: Andy Presby, Winchel Chung (www.projectrho.com/rocket/index.html), Dr. of polycyclic organic molecules consisting of fused, conformationally rigid Jonathan Lunine of the Lunar and Planetary Laboratory, Dr. Carolyn Porco, Mission Director of the cages.) The system includes internal radio communications, fuzzy logic design Cassini Imaging Team, Keith and Carolyn Henson of the L5 Society, Dr. Michael R. Lewis of the Kaman data storage, and a robot that can disassemble faulty engines and drills, test Sciences Corp., Dr Nathan Strange of JPL, Ken Burnside of Ad Astra Games, Eric Finley, Neil Sofge of Fat Messiah Games, currently at the Goddard Space Flight Center, the late Dr. Robert Forward of them, and replace them with new diamondoid components made on site. This Hughes Research Labs, Dr. Robert Zubrin of the Mars Society, Dr Isabel Braun of MAGIC, Dr. Andrew device is called a Santa Claus machine, because of its capacity to make Pakhomov of the UAH Laser Propulsion Group, Peter Kokh of the Moon Society. anything you want, including copies of itself. However, in practice self- Inspiration: K. Eric Drexler of the Foresight Institute. His article “The Useful Pieces of Space” in the May reproduction (of disassembled parts) is vastly easier than self-assembly of 1979 L-5 News was inspirational for starting this game 30 years ago. He contributed data on parts. The machine illustrated (like the 2009 RepRap open-source project) nanotechnology, photon sails, & dust radiators. can self-reproduce, but relies on humans to assemble itself. Special thanks to Leik N. Myrabo, Ph.D. of the Rensselaer Polytechnic Institute, who hosted my paper at John Von Neumann, “Theory of Self-Reproducing Automata,” Univ. of Illinois Press, 1966. the 1982 Joint Propulsion Conference. Leik is the guru of laser-beam power.

Fission and Fusion Nuclear Power – The nuclear energy Fusion Containment – There are five general methods for confining plasmas long enough and hot enough for achieving a of heavy “high Z” atoms (uranium, thorium, etc.) is unleashed positive Q: closed-field magnetic confinement (see D-T Fusion Tokamak), open-field magnetic confinement (see 3He-D mirror), by splitting them. In contrast, the nuclear energy of light inertial confinement (see D-D inertial fusion), electrostatic inertial confinement (see 6Li-H fusor), and cold fusion (see H-B cat atoms (hydrogen, helium, etc.) is released by fusing them fusion). Of these reactions, the fusion of deuterium and tritium (D-T), has the lowest ignition temperature (40 million degrees K, or together. The specific energy of nuclear fuels used in the 5.2 keV). However, 80% of its energy output is in highly energetic neutral particles (neutrons) that cannot be contained by game are: 6Li-H and H-B fusion = 73 TJ/kg, uranium fission magnetic fields or directed for thrust. In contrast, the 3He-D fusion reaction (ignition temperature = 30 keV) generates 77% of its = 82 TJ/kg, D-T, 3He-D, and D-D fusion = 345 TJ/kg. The energy in charged particles, resulting in substantial reduction of shielding and radiator mass. However, troublesome neutrons chemical fuels used in the game are a million-fold lower: comprise a small part of its energy (4% at ion temperatures = 50 keV, due to a D-D side reaction), and moreover the energy metastable He = 477 MJ/kg and H2-O2 = 14 MJ/kg. The density is 10 times less then D-T. Another disadvantage is that 3He is so rare that 240,000 tonnes of regolith scavenging would candidate fusion fuels D-T, 3He-D, D-D, 6Li-H, and H-B refer be needed to obtain a kilogram of it. (Alternatively, helium 3 can be scooped from the atmospheres of Jupiter or Saturn.) to isotopes of hydrogen, helium, lithium, and boron. The Deuterium, in contrast, is abundant and cheap. The fusion of deuterium to itself (D-D) occurs at too high a temperature (45 keV) positive charge on these nuclei creates an electrical repulsion and has too many neutrons (60%) to be of interest. However, the neutron energy output can be reduced to 40% by catalyzing this that must be overcome by temperature and confinement time reaction to affect a 100% burn-up of its tritium and 3He by-products with D. The fusion of 10% hydrogen to 90% boron (using in order for them to fuse together. Therefore, input energy is 11B, the most common isotope of boron, obtained by processing seawater or borax) has an even higher ignition temperature (200 required to obtain output energy, and the ratio of energy keV) than 3He-D, and the energy density is smaller. Its advantage is that is suffers no side reactions and emits no neutrons, and injected to the thermal energy obtained from fusion is called a hence the reactor components do not become radioactive. The 6Li-H reaction is similarly clean. However, both the H-B and 6Li-H reactor’s Q factor. At ignition, Q goes to infinity. reactions run hot, and thus ion-electron collisions in the plasma cause high bremsstrahllung x-ray losses to the reactor first wall. 23 10.0 Chad Marlett’s Basic Strategy Guide 11.0 Joe Schlimgen’s Frequently Asked Questions 1. Resource Exploitation Track: Each ET factory of a given spectral type has a VP value (or WT Q: What makes a valid rocket? Does a rocket need a crew? value for a product) that goes down in value as the number of factories increase. Depending on the board situation, break the monopolies of the leader, and try to get some of your own. A: A valid rocket is any number of cards, regardless of type, with a total dry mass of no more than 15. In particular, a rocket does not require a crew (but a crew will protect the 2. Robonauts/ISRU: Of the 9 white robonauts, 2 are buggy, 4 are raygun, and 3 are missile. rocket from glitches in the expanded game). However, to be able to move, a rocket needs Choose a robonaut aligned to your chosen target as follows: a thruster and enough fuel to get it to its destination, and possibly the means to return. 2A. Missiles Robonauts: The missiles are ISRU 2/3/3 and all act as inefficient thrusters. The In the expanded game, the thruster may require additional support cards such as reactors missiles obviously have to be landed to be useful and allow only one prospecting roll, so this or generators in order to operate (and the support cards may require support cards). effectively limits there usefulness to size 3 or greater sites (unless you are lucky) with two or three water drops.The 9-6 can land on Luna, but doesn't have enough ISRU to prospect there; kind of Q: In order to build a factory, do you have to decommission cards with product letters an odd card to use. The two 5-4's seem to have good targets at hertha, eichsfeldia, and minerva. that match the site's letter? 2B. Buggy Robonauts: These are essential for the isolated size 1 sites to give you a decent A: No. The product letters of the refinery, robonaut, and support cards decommissioned success chance (khufu, deimos, phobos, phaethon, olijato, aneas, etc. They are almost required to industrialize are irrelevant. For example, in the basic game you could build a factory at for Mars - why go to the trouble of landing on Mars and not claim the whole enchilada? a type `M' world by decommissioning a Basalt Fiber Spinning refinery (type `S') and a 2C. Raygun Robonauts: These mass the highest, but they are the keys to the asteroid families and Kuck Mosquito robonaut (type `V'). However, the card you choose to be the factory do not have to land to prospect (unless the site has an atmosphere). A raygun robonaut has the product must have a product letter that matches the site's spectral type. only 1 ISRU in the white cards. Q: The signpost from LEO to Mars lists three burns, but the colored path requires three 3. Refinery: These are fairly interchangeable in the basic game, other than mass (two 3's and five burns and a Hohmann transfer (two more burns). Shouldn't the signpost list five burns? 4's). It is a good idea to produce either refineries or robonauts at your first factory, so I advise choosing a refinery with a product on its black side matching your first factory site. If you are going A: Signposts list the minimum number of burns required to reach the destination. They for a “C” site (mars, ceres), note that there are no “C” refinery product types, so you may wish to do not list the Hohmann transfers because the rocket may stop at each transfer orbit pick up one of the two “C” robonauts (excimer lasers or MET steamers). and change directions at the start of the next turn without spending any burns. 4. Thrusters: The 1-0 sails are useful for Mars or beyond only with very light payloads or with ESA Q: If I have multiple factories with the same product letter, how do I keep track of which help. The 3-1 and 5-1 (expanded card) are quite useful. The 3-2, 5-2, and 4-3 are not very efficient product goes with each factory? and fairly heavy. The 3-4 solar thruster is tricky to use, but it does weigh 0. The 7-4 NERVA is useful on a few targets as a lander (size 6 vesta and ceres). I could see some bidding wars A: To simplify bookkeeping, products are only associated with factories by product letter. developing over the thrusters, as 'thruster denial' might be a valid early game tactic. Therefore, if you have multiple factories with the same product letter, you may produce any of those products at any of those factories. 5. Crew: NASA, ESA, and PRC can fly to Mars and claim the Hellas Basin with their crew cards alone and 6 WT (if they survive the landing). The crew ISRU ratings are too poor to claim other Similarly, you may retool by flippling any card in your hand matching a product letter of nearby sites. You can leave crew outpost at site to form a future colony - the only one-way trip you any of your factories. If you exceed the limit of one black card per factory per spectral can really plan with crew if you are not the PRC. Note that the PRC crew must be present to claim type, you must flip one of those black cards to white while it's in your hand. For jump, and other player's crew prevents this. example, if you have two `S' factories, two black `S' products, and retool another `S' product, you must flip one of your previous `S' products back to white (and may need to 6. ET Production/Retooling: Note that having a white card in your hand matching your new ET decommission it first). factory's spectral type when you build it saves you a turn so that you don't have to Retool later. 7. ISRU Refueling: You don't have to have a claim to refuel at a site. This could come in handy at Q: When industrializing, can I use a crew card instead of a robonaut? deimos, since it is difficult to prospect, but easy to land on. A: No. To simplify bookeeping, a single factory cube is considered unmanned, two 8. Aerobraking: Don't forget that you don't have to use any lander fuel to land after aerobraking. Of factory cubes are a manned factory and protect it from water theft. course, taking off again is another story. 9. Failure Is Not an Option: Paying the 4WT to avoid making a crash or aerobrake roll is a must if Q: Is it realistic to land on a site without spending any fuel? you are ahead in VP and have a lot riding on the mission. A: The lander fuel penalty simulates the chemical boosters used to land or lift off. If the 10. Space Ventures: Aiming for a three-of-a-kind M, V, or S set of claims is a decisive VP edge. rocket's thrust is high enough it does not require the boosters. You are still spending The space elevator is unlikely in the basic game - three M sites plus 7WT might be a bit tough fuel, however, because the number of burns leading into and out of a site match the before the game ends due to the number of ET factories. delta-V required to land on or lift off of that site.

Rocket #2 Rocket #1 Sail #1 LEO to Comet Encke Rocket #3 1 -1 1 3•1 +0 Each Hohmann 6•2 -2 2• 2 1•0 +1 5/4 pivot during a Fuel Fuel Rocket #5 Fuel = 1 Fuel 5 burns basic, MAR burned = 3 move is 2 burns. burned = 8 burned burned = 0 S 1 4 burns expanded. FLYBY 13•2 -2 LEO HEO GEO L2 Fuel start burned = 5 1st burn. 2nd burn. 3rd burn. 4th burn. Movement Example following Route Blue. Five rockets and a sail take route blue to Comet Encke. Their positions and fuel steps expended after their first moves are shown. Rocket #1 has Rocket #4 outbursts 1V a modified thrust of 2 - 1 = 1, and so gets no farther than the first burn. But rocket #5 moves past all 5 7•1 -1 Comet Encke burns, and makes 2 Hohmann pivots (2 burns ea) to arrive at Encke in one turn. It makes a direct landing Fuel 5th burn, on Encke that costs no fuel. (In the expanded game, rockets #2, #3, #4, and #5 use one less burn, due to burned = 6 roll hazard. the Mars slingshot bonus, and can land on Encke only during the blue sector.) LE Wet mass The rocket #6 used in this #5 startO Movement Example from LEO to the martian moon Fuel modifier example has the thrust (4), 1 HE

consump- fuel consumption ( 2), O Phobos [basic game] or Mars [expanded game].

tion r a

Thrust and wet mass thrust d i

a L4

t ISRU

modifier (-1) shown. i

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A b PLATFORMS The total modified R basic game. e -1 e FL TH 2 l YB s 4• thrust is 4 - 1 = 3. t t Each Hohmann pivot burns as 1 Y in d #4 a 6 t much fuel as entering 2 burns. - Luna io one re-roll Buggy: Destination Phobos - Rocket #6 a n cc L1 M [basic game movement example]: ars First Turn: Rocket #6 moves from LEO through Make 1 prospecting HEO, L1, L5, and L1, ending with Phobos touchdown. re-roll. Prospect all It enters 3 burns during its move (its maximum). Each costs ! steps Moon boosts are Entering this burn generates an sites linked by road. #3 treated as a normal Event Roll in the expanded game. of fuel, rounded up to 2 steps of fuel total. Because its modified intersection in the thrust is greater than Phobos’ size, no lander fuel is needed. L5 basic game. Raygun: Destination Mars - Rocket #7 [expanded game movement example]: Destination Phobos First Turn: Rocket #7 moves from LEO through L4 and the moon boost, ending Rocket #6 ORBITAL PROSPECT its move where shown. It entered three burns, and made a Hohmann pivot (= 2 After entering 1 -1 Prospect all burns). But because of the moon boost bonus, one of the 2 burns spent HEO, this freighter #2 4• 2 adjacent non- coasts to here. Fuel making the pivot is free. Each of the 4 burns costs 3 steps of fuel. It must roll L1 burned = 2 atmospheric spaces for the radiation belt L-point entered (the radiation level is 1d6 minus 5). 1C phobos #0 Second Turn: Rocket #7 makes a Mars flyby and two aerobrakes, to Halts here so 10C land at the Arsia Mons Caves. Because of the slingshot bonus, the HEO as to move a sia mons Missile: ar ves burn is free. Because of the aerobrake bonus, no lander fuel is needed, new direction ca next turn. but two hazard rolls are made for the two aerobrakes. Mars Rocket #7 e May act as a Destination LEO [freighter movement example]: Surfac thruster. -2 MARS Size 10 The numbered cubes show the yearly positions of a freighter 7•3 FLYBY HEO #1 that starts on an ET factory in Arsia Mons caves, and Fuel departs for Earth. The trip takes 5 years, and [expanded #1 burned = 12 [email protected] game] rolls a radiation risk during the final year. 24 www.sierramadregames.com