Choices of Selected Trades for the Cis-lunar One Transportation Architecture

1. Choices of Selected Trades for the Cis-lunar One Transportation Architecture by Doug Plata, MD, MPH Page 1

2. About Cis-lunar One is a proposed cis-lunar transportation infrastructure which could start functioning with as little as a single heavy lift vehicle. It involves reusable in-space vehicles to a lunar pole for the telerobotic harvesting of lunar ice for water. The in-space and surface operations are described in detail as are the timeline and estimated costs. Page 2

3. Terminology ACES – Advanced common evolved system Condor-LL – In-space craft in the lunar landing configuration Condor-OTV – In-space craft in the orbital transfer configuration Condor-FD – In-space craft in the fuel depot configuration EELV – Evolved expendable launch vehicle EML – Earth-Moon libration point GEO – Geostationary orbit ISS – International Space Station LEO – Low Earth orbit LH – Liquid hydrogen LM – Liquid methane LOX – Liquid oxygen LLO – Low lunar orbit NASA – National Aeronautics and Space Agency RTG – Radioisotope thermoelectric generator SLS – Space Launch System Page 3

4. Overview of the Cis-lunar One Architecture A single Falcon Heavy launches a lunar lander and discharges a LOX tank at LLO. The lander then proceeds to land at the permanently sunlit rim of a crater at the lunar north pole. Solar panels are discharged. Then the lander hops down into the permanently shadowed crater while draping a wire thereby allowing continuous electricity to flow from the rim to the worksite in the crater. The lander lands belly down, discharges an excavator which scoops up icy regolith. The excavator steams out volatiles from the regolith and then transports them to the lander where distillation separates out the water and carbon monoxide. Using electrolysis and chemical reactions, methane and LOX is produced. Once the lander is refueled, it blasts off up to the LOX tank where excess LOX is transferred. The lander then descends to the worksite and the process is continued for another round trip to the LOX tank. Follow-on launches from Earth would include redundant equipment, spare parts, more LOX tanks and variants of the lander including orbital transfer vehicles with heat shields and man-rated versions of the craft. The in-space craft would be naturally reusable and so could build up significant flight experience even with relatively few launches. When the LLO LOX tank becomes full, the in-space craft would push it to EML1 where it could serve missions beyond the Earth-Moon system. A later variant of the craft would aerobrake into any LEO inclination in a just-in-time manner and would be able to dock with a satellite in LEO and boost it to GEO or anywhere else including on interplanetary missions. As the in-space craft gained flight experience, crewed missions would follow to the crater rim where an initial, minimalist base would have been established by previous cargo missions. The purpose of the crew would be to maintain the teleoperated equipment as well as to extract metals from the regolith for melting and casting to produce the bulky parts of additional equipment. It is proposed that this specific architecture would be one of several competing approaches funded via a NASA public-private partnership serving both the needs of NASA and commercial companies. These programs would be comprised of four sub-programs very analogous to the current public-private programs. Similarly, NASA would make payments for milestones met and serve as the “anchor tenant” by purchasing supply and/or propulsion services. It is estimated that the timeframe for the Cis-lunar One program from full funding to first launch would be five years. From first launch to the initial income would be approximately 18 months. From first launch of teleoperated ice-harvesting equipment until the first human return would be four years. In total, from initial funding until a fully operational base of eight astronauts would be approximately 10 years. As with the current public-private programs it is proposed that multiple companies be funded in order to ensure a marketplace with at least two competitors. It is estimated that to total cost for the Cis-lunar One program would be $2.38 billion over 10 years. Page 4

5. 1) Launcher CHOSEN – No specified launch vehicle Any of several launchers could be used to launch the first and subsequent Condors. Each have their own technical and cost considerations. But non-calculable factors such as politics and motivation make the best selection of launcher unknowable at this time. Not – Space Launch System The SLS Block 1 is more than enough to launch in-space vehicles even starting with methane engines. Although the per-kilogram expense of the SLS is likely to be considerably higher than that for the Falcon Heavy, the SLS is in need of more missions to justify its existence and so those launches could be donated to the public-private programs. Not – Falcon Heavy Falcon Heavy is likely going to be the cheapest per kilogram launcher in the foreseeable future. It’s size is adequate to launch the mass of the initial mission provided that a one-time RL-10 hydrolox engine is used. Thereafter, with propellant at LLO or EML1/2, the Falcon Heavy can launch in-space vehicles with methane engines. However, SpaceX has shown little interest in lunar and cis-lunar missions. However, they would likely sell launches and upper stages to anyone who wishes to purchase them. Not – Delta 4s or Atlas Vs It would take two Delta 4s or Atlas Vs to launch the initial mission but only a single launch to loft a dry Condor up to LEO should propellant or propulsion service be available at that time. However, the $/kg cost would likely be greater than that for a Falcon 9. Page 5

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7. Initial Condor-LL Design • CHOSEN – Condor-LL = upper stage with RL-10 • Having the upper stage be the Condor-LL would reduce the cost of launch since one would not need to purchase an upper stage (apart from the Condor-LL) and since the upper stage engine would be used in the Condor-LL and therefore would save in weight. The RL-10 is a LH/LOH engine necessary for the mass fraction requirements of the initial mission and has excellent flight history. This design does however entail a tail landing with the disadvantages noted below. • Not – Condor-LL within fairing • This is the more standard configuration for a payload but it limits the amount of volume for the Condor-LL. It would also mean that additional engine mass would be necessary thereby taking away from ultimate payload mass. • Not – Condor-LL = upper stage no Merlin engine • In this option, the Condor-LL would have no large tail engine but four or more “limb” engines pointing perpendicular to the direction of flight at separation. It could then fire its hind engines rotating the Condor-LL 90 degrees and then fire all engines until it achieves a parking orbit. In this way the landing engines could serve as the upper stage engines thereby minimizing engine mass. Page 7

8. Initial Propellant Type – Depends upon launcher type. • CHOSEN - LH/LOX • The orbital mechanics require LH for a single Falcon Heavy launch. • Not - LM/LOX • A LM engine would result in negative payload mass on the lunar surface. • Not - Ion propulsion • Ion propulsion could be used with a LM Condor-LL thereby avoiding the requirement of two Condor-LL versions (one LH and one LM). However, the use of ion propulsion would introduce additional complexity into the plan and would probably take months to proceed to LLO thereby increasing boil-off. Page 8

9. Cracking Location • CHOSEN - Sunlit rim • A “Peak of Eternal Light” could provide nearly continuous solar power to power operations in the permanently-shadowed crater if connected. • Not - LLO • With the initial mission, there would not be enough propellant to go from LEO to the lunar surface and then all the way up to LLO before new propellant could be produced. • Not - Shadowed crater floor • This would require nuclear power (e.g. RTG). RTGs do not provide enough power to crack the amount of propellant needed within a reasonable time. Page 9

10. Initial Landing Sites – Depends upon assumed previous prospecting mission. • CHOSEN - Sunlit rim of (Hinschelwood) crater first then hop to shadowed crater floor. • The lunar north pole is less steep and remote sensing evidence suggests large quantities of consolidated ice in layers which would make for safe harvesting (microwaves) if true. Hopping (i.e. flying) from the rim to the shadowed crater floor will be a rare requirement and should not be significantly more risky than the take-offs and landings that the program will require. • Not - Bottom of permanently-shadowed crater (Hinshelwood) then hop to crater ridge. • In this scenario, residual propellant is used in either a fuel cell or an internal combustion engine to provide the electric power for ice harvesting operations. Once enough water is harvested, the Condor-LL hops to the rim where the water is electrolyzed into propellant thereby allowing a LLO circuit run. However, without power being transmitted from rim to floor, it would require extra hops thereby increasing the risk of accident. Page 10

11. Cracking Location • CHOSEN - Sunlit rim • A “Peak of Eternal Light” could provide nearly continuous solar power to power operations in the permanently-shadowed crater if connected. • Not - LLO • With the initial mission, there would not be enough propellant to go from LEO to the lunar surface and then all the way up to LLO before new propellant could be produced. • Not - Shadowed crater floor • This would require nuclear power (e.g. RTG). RTGs do not provide enough power to crack the amount of propellant needed within a reasonable time. Page 11

12. Power in Shadows • CHOSEN - Draped superconducting tape • After landing and establishing an array of solar panels, the Condor-LL could lift off, hover briefly, drop a wire and immediately begin draping wire over the edge of the crater. At the point whereby it is calculated to be the boundary for being permanently shadowed, superconducting tape could be spooled out. If necessary, this would limit the amount of mass in the cable thereby increasing other payload. • Not - Fuel cell from reserve propellant • Fuel cells are proven in-space technology from the Apollo era. There will be reserve propellant for safety which could be used to provide electrical power for ice harvesting operations. One could also plan on a certain amount of reserves beyond what is necessary for margins. However, the ease of draping a wire from the sunlit rim to the shadowed worksite is low enough to not warrant drawing from payload margins. • Not - Internal combustion engine using LH/LOX • ULA has purchased technology for an internal combustion engine for their ACES system. • Not - Beamed power from sunlit rim • Beamed power would still require an initial hop from the sunlit rim to the shadowed worksite but energy transformations would result in efficiency losses. • Not - RTG • RTGs don’t provide the amount of power needed to electrolyze propellant-quantities of water. Also, given nuclear sensitivities, companies may be reluctant to use them. Page 12

13. 14) Surface Equipment CHOSEN - dexterous telerobot x 2 The Robonaut 2s are already well developed and functioning onboard the ISS. With intelligence, equipment could be made to be easily repaired by dexterous telerobots. CHOSEN - excavator/oven/transporter Pieces of equipment sharing common elements are consolidated into a single piece of equipment thereby requiring only a single launch, less mass, and fewer material transfers. CHOSEN – Electrolyzer onboard the Condor-LL Given the ambient cryogenic temperatures of the shadowed crater, methane and oxygen could be naturally liquefied in the fuel tanks of the Condor-LL thereby reducing the need for additional storage tanks. CHOSEN – Condor-LL distiller / chemical reactor A distiller and chemical reactor onboard the Condor-LL would allow the separation of H2O and CO and their production into methane and LOX. Unused volatiles could be stored in bags near the worksite for later use such as for fertilizer. The mass of the distiller / chemical equipment would be a relatively small amount of mass on the Condor-LL and it travels to and from the LLO LOX tank. Page 13

14. Harvesting (based upon prospecting results) • CHOSEN - Bucketwheel icy regolith into open body. Hatch is closed and volatiles heated out. Volatiles collected into onboard tanks. An LCROSS investigator described the ejecta as being fluffy thereby suggesting easy harvesting using a bucketwheel approach. Steaming out the volatiles within the excavator means fewer trips. • Not - Steaming out using microwave under an umbrella into onboard tanks. • This approach would mean less handling of the abrasive regolith thereby reducing wear and risk of seizure. However, with a poor seal, some volatiles will be lost for the same amount of energy used. Page 14

15. Repairs (based upon experience in Earth- based lunar simulation labs) • CHOSEN - Redundant of those pieces most likely to break down. In the initial mission, a back-up dexterous telerobot and a back-up excavator would ensure continuity of operations as well as a means to extricate stuck equipment. • CHOSEN - Surface equipment designed for easy replacement using spare parts. Like modern bicycle wheels, attachment points would be designed for easy “pop-on-pop-off” parts. Systems would have no free bolts. Dexterous telerobots would be designed to replace non-functioning parts. • CHOSEN - Spare parts • Extra spare parts would be included in the initial mission based upon laboratory experience and spare parts would be chosen for follow-up missions based upon what needs replacing. Page 15

16. Fuel Depot Location • CHOSEN - LLO • For the initial mission, a fuel depot at LLO can be filled more quickly than at an EML point. Later, a Condor-LL could boost the fuel depot from LLO to an EML point which would be of greater use to missions beyond the Earth-Moon system. • Not - EML1 (halo) • A shorter travel time to and from Earth than EML2. • Not - EML2 • Advantageous for orbital plane changes towards LEO but a longer travel time to and from Earth than EML1. Page 16

17. Heat Shield • CHOSEN - Pop out on front. No flaps on the back. • Pop out heat shield in the front would increase the surface area more than just heat shield painted on. Control of the shape of the heat shield might also provide some degree of directional control. • Not - Painted onto front and heat flaps towards rear. Like the visualizations of the reusable Falcon 9 upper stage. • Not - Fold out umbrella at front and heat flaps towards rear • Provides more cross-sectional area but the rear control flaps may be blocked by the front shield. Additional mass. • Not - Aerobraking only (no heat shield?) • Used by the Mars Reconnaissance Orbiter. Requires no heat shield yet may have to make numerous passes over a period of weeks, though may have minimal heating. • Not - Large turtle-shaped (assembled in-space) • Too hard to assemble. Page 17

18. Humans • CHOSEN - After Condor proven safe with delivery of cargo. • Similar to how the Dragon capsule is being man-rated. • CHOSEN - Launch on EELV-class rocket (e.g. Falcon 9). Transfer to proven Condor. • CHOSEN - After fuelled vehicle on surface waiting and sufficient fuel at LLO for abort-to-orbit contingency. Page 18

19. 24) Funding Mechanisms • CHOSEN – “Lunar COTS” program. • Based upon the proven and highly successful COTS , CRS, and CCP programs. Would call for no increase in NASA’s budget, no adjustments to the current NASA budget profile, and would not try to take on the politically-supported SLS / Orion program. This program needs the large up-front investment, longer-term return, and high-risk development of infrastructure which government is well positioned for. • Not – Lunar development as a budget-dominating paradigm change. • Administrations don’t want to reverse directions since it would reflect poorly on their previous decisions opening them up to political criticism. Powerful entrenched political forces would defend the status quo. • Not – Strictly private investment sources. • The up-front costs are too rich for the blood for investment sources, first return on investment is too long, and the risk is too high. Page 19

20. Addendum - Non-highlighted Trades 4) Launch Trajectory CHOSEN - Direct injection to LLO (4.04 km/s) Not - Direct injection to EML1 Not - To LEO parking orbit? Not - Direct injection to lunar surface 5) Path to Moon CHOSEN - Drop off LOX tank at LLO Not - Go directly to lunar surface 6) Communications CHOSEN - 5 satellites in 86 degree polar orbits Not - Sunlit peak Not - Existing polar satellite 10) Landing Legs CHOSEN - Wheels Not - Landing legs Not - Skids 11) Reserve Propellant CHOSEN - Enough for harvesting & to reach LLO Not - Enough for a hop to shadows and a hop to sunlit rim Not -Enough for a hop to shadows, a hop to sunlit rim, a hop to shadows, and a hop to sunlit rim (allows electrolysis to start while rest of water is harvested) Not - Only enough for a hop (and drape) to the shadows. 13) Equipment discharge CHOSEN - End open - drive-off Not - Gantry crane Not - Rotate body Not - Crane out side of vertical craft 16) Distillation CHOSEN - On-board the OTLV with non-used volatiles bagged and transported a safe distance away from the OTLV. Not - Distillation 18) Becoming Unstuck CHOSEN - Dexterous telerobot attaches a cable to stuck vehicle, attached the other end to a rock. Winch helps stuck vehicle get moving. 20) Delivery CHOSEN - Only to LOX tank at LLO. Separate OTV from lunar lander. Maybe later launch of OTV vs ion propulsion. Not - EML1 LOX tank until able to complete Cis-lunar Circuit. Not - LH/LOX depots at either LLO or EML1. 23) Emergency Human Return CHOSEN - Launch of OTLV from the lunar surface with transfer to a capsule at LEO. Not - Launch of OTLV from the lunar surface with attached capsule for direct reentry. Page 20