Lunar Cargo Capability with VASIMR Propulsion

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1 Lunar Cargo Capability with VASIMR Propulsion Tim Glover, PhD Director of Development

2 Outline Markets for the VASIMR Capability Near-term Lunar Cargo Needs Long-term/VSE Lunar Cargo Needs Comparison with All-chemical Lunar Cargo System Summary

3 Main Points A solar-powered VASIMR-based cargo tug operating at 5,000 s Isp between LEO and LLO can double the payload transferred from low Earth orbit to low Lunar orbit, compared to a 450 s Isp chemical Trans-Lunar Stage, given a six month transit time. Ad Astra is working towards a launch and space test of the VASIMR technology at the 200 kw power level, completely funded by private investment. There is a wide continuum of performance in the parameter space of power level, cargo mass, transit time and specific impulse. The immediate market need (within two years) is for payloads of 100 to 1000 kg delivered to the lunar surface. Capability needed is similar to that of the 1960 s Surveyor program. The long-term VSE requires many tons of cargo to the lunar surface per year. The VASIMR technology could be scaled to meet this need.

4 Near-term Market Customers with a need for access to the lunar surface, for payloads of tens to hundreds of kilograms: 1. SMD (NASA Science Mission Directorate) has a goal of sending 1-2 pure science missions to the lunar surface each year (typical payload 300 kg ). 2. ESMD (NASA Exploration Systems Mission Directorate) needs access to the lunar surface for applied science projects that will pave the way for manned exploration: eg., regolith characterization, surface testing of exploration hardware. 3. Foreign market there are 9 16 countries (including India, S. Korea, Japan) that want to get hardware to the lunar surface. 4. Commercial a number of companies have business plans that involve landing equipment on the lunar surface (including Lunar X-prize competitors), such as routers and observatories. 5. Other US govt agencies DARPA, other DoD, NSF.

5 Near-term Need is Similar to Surveyor Capability Surveyor mass at TLI: 1000 kg Mass landed on lunar surface: 300 kg

6 Surveyor Landing Propulsion 95% of 2500 m/s approach v provided by solid retro rocket (620 kg, 250 s Isp). Attitude and final landing provided by 3 throttleable hypergolic liquid vernier engines (hydrazine, nitrogen tetroxide; thrust lb)

7 Surveyor Solid Rocket (60% of S/C mass)

8 Serving the Near-term Market A 2 mt 200 kw VASIMR-propelled tugboat, shuttling back and forth between low Earth orbit and low lunar orbit, could deliver approximately 8 tons to lunar orbit every six months. Smaller cargo loads can be delivered in less time. A 1.5 mt cargo could be transferred in 3 months. If this cargo consists of a payload and a lander using storable propellants, the lander and its propellant will weigh approximately 1000 kg, leaving 500 kg for payload delivered to the surface. If Zero Boil-off (ZBO) propellant storage can be developed for a lander using LOX and LH2, the useful cargo fraction could be raised to ½ of the mass transferred to low lunar orbit.

9 200 kw Lunar Cargo Demo Flight 1500 kg Lunar satellite 1500 kg Lunar lander PV Array 600 kg Magnets 300 kg RF amps (PPU) 100 kg Structure 100 kg Thermal systems 100 kg Avionics 50 kg 20% margin 250 kg Ar prop. 900 kg Ar tank 100 kg Total 2500 kg (not to scale) payload delivered to LLO in 3 months : 1500 kg IMLEO: 4000 kg Cargo to lunar surface: 500 kg (250 s Isp landing system)

10 200 kw Lunar Demo Flight 4 mt IMLEO stage # time[days from LEO departure] propellant[kg] thrust direction along V angle 60 across Z across R across RM across ZM across RM goal spiral from LEO spir & incl incl only to 20 RL to orbit incl Moon spiral to LLO

11 capture into high lunar orbit and descent to LLO (lunar frame of reference) stage # time [days from LEO departure] propellant [kg] thrust direction goal view in plane of final orbit and in plane of Moon s orbit across R to 20 RL across RM to orbit across ZM incl Moon across RM spiral to LLO (NOT optimized) facing final polar orbit plane from top

12 Long-term Market Lunar exploration on the scale of the VSE (Vision for Space Exploration) will require tens of tons of cargo annually, in the form of habitats, machinery, vehicles, and supplies. (Chemical cargo lander shown at right ). Present planning assumes that all of this cargo will be transferred from LEO to the Moon s surface by chemical propulsion. NASA images An unmanned cargo capability based on electric propulsion could offer significant cost savings to a lunar exploration program.

13 All-chemical Cargo Flight For purposes of this comparison, we assume a heavy lift launcher capable of delivering a 100 mt Trans-Lunar stage to low Earth orbit (LEO), comparable to Ares V. The Trans-Lunar stage is dominated by the mass of the LOX and LH2 propellant needed to get the cargo vehicle from LEO to low lunar orbit (LLO).

14 All-Chemical Lunar Cargo Performance (LOX/LH2) (450 s Isp throughout, masses rounded to nearest mt) IMLEO: 100 mt TL stage m TL = 51 mt LOI: lunar orbit insertion m m e LOI TL = e v/u 1000 /4410 LOX/LH2 used to get to LLO in 3 days: 60 mt = LOI burn: v = 1,000 m/s m LOI = 40 mt discard TL stage m = 5 mt m LLO = 35 mt TLI: trans-lunar insertion TLI burn: v = 3,000 m/s m m e TL LEO = e v/u 3000 /4410 = lunar descent: v = 2,000 m/s DL mass = x cargo cargo = 0.51 x m LLO cargo mass on lunar surface = 18 mt

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16 VASIMR Lunar Cargo 5,000 s Isp OTV separates and returns to LEO IMLEO: 100 mt OTV: 20 mt (dry) 3 mt of Argon used for return 18 mt of Argon used to achieve LLO in 6 months m LLOI = 79 mt discard CDV +argon tank m = 4 mt m LLO = 75 mt lunar descent: Spiral from LEO to LLO: v = 8,000 m/s (Edelbaum) v = 2,000 m/s DL mass = x cargo m m e TL LEO = e 8000 /49000 v/u = cargo = 0.51 x m LLO cargo mass on lunar surface = 38 mt

17 Comparison of 100 mt IMLEO Mass Allocations 5 mt lander (dry) 12 mt lander propellant 18 mt cargo 12 mt lander (dry) 25 mt lander propellant 38 mt cargo 60 mt Trans-Lunar propellant 21 mt Trans-Lunar propellant 5 mt engine, tanks 5 mt structure 450 s all-chemical system 5,000 s VASIMR system

18 Lightweight Stowable Power is Essential SLASR: Stretched Lens Array, Square Rigger (deployment). Optimized design, thoroughly tested, prototypes built, components tested in space technology is ripe for implementation. 80 kw/m 3, stowed Please see for details on the SLASR technology. Video clips of SLASR prototype deployment demonstration at ATK, 2005.

19 Effect of Transit Time and Specific Impulse While extending transit time beyond 6 months adds only slightly more cargo mass, it significantly reduces array power and cost. Landed Performance impaired for transits less than six months, due to increased power and propellant mass. lander CDV mass fixed at 100 mt cargo Argon propellant

20 Effect of OTV Specific Mass (α) At Isp s above ~ 9,000 s and OTV α s above ~ 9 kg/kw, performance degrades and power rises sharply with increasing Isp. Note: these plots are independent of thruster type (60% efficiency, independent of Isp); 2 MW power level. Landed Required propellant rises sharply below 5,000 s. At 5000 s, performance is relatively insensitive to OTV specific mass: doubling it from 6 kg/kw to 12 kg/kw reduces landed cargo mass by only 8%. Even though specific mass is still slightly uncertain, this has negligible impact on lunar cargo application.

21 Summary A solar-powered VASIMR-based cargo tug operating at 5,000 s Isp between LEO and low lunar orbit can double the payload transferred from LEO to LLO on a six-month flight, compared to a 450 s Isp Trans-Lunar Stage, given a six month transit time. Ad Astra is working towards a launch and space test of this technology at the 200 kw power level, completely funded by private investment. There is a near-term need for access to the lunar surface for 100 kg to 1000 kg payloads, to support science, commercial, and NASA exploration programs. A 100 kw class VASIMR lunar tug could serve this market, doubling the mass transferred to the lunar surface relative to all-chemical propulsion. There is a long-term need by VSE for tens of tons of lunar cargo per year. A 2 MW VASIMR-propelled tug operating at 5,000 s Isp making a six-month transit could deliver approximately 38 mt to the lunar surface, using a LOX-LH2 lander, compared to 18 mt for a 450 s Isp all-chemical cargo system.