www.dlr.de Chart 1 Suitability of reusability for a Lunar re-supply system Etienne Dumont Space Launcher Systems Analysis (SART) Institut of Space Systems, Bremen, Germany Etienne.dumont@dlr.de IAC 2016 28th September 2016 Guadalajara, Mexico
www.dlr.de Chart 2 Introduction Initiative of ESA General Director: Moon Village ROBEX (Robotic exploration under extreme conditions): consideration of various modular robotic Moon missions Establishment of a Moon base (175 tons) Establishment of a telescope We have the technologies to go to the Moon, but how to reduce the costs to allow a sustainable presence on the Moon? What is the most efficient way to transport infrastructures to the Moon? Source: DLR
www.dlr.de Chart 3 Overview Selected key technologies RLRV design Operations, missions and performances Comparison with the Apollo LM Conclusions Source: NASA
www.dlr.de Chart 4 Selected key technologies Propellant and engine: Isp 311 s (LM engine) vs over 450 s (RL-10 and Vinci) 60 to 67% propellant more for a descent to the Moon from LLO or EML1 Several decades of experience with cryogenic propulsion Pump-fed engines have reached a high level of reliability Advantages for the structure In Situ Propellant Production (ISPP) O2 can be extracted from regolith Estimations: 6.6 x 10 12 kg water ice Source of H2 and O2 RL-10 Source: NASA Temperature map from LRO Source: NASA
www.dlr.de Chart 5 Selected key technologies Reusability: Developments on the Earth of VTOL launch vehicle: New Shepard, soon? Falcon 9 For in-space transfer vehicles and lunar landers no hypersonic re-entry No heat shield Low loads levels (mechanical, thermal) Limited V Moon -> LLO -> Moon: 3.8 km/s Moon -> EML1 -> Moon: 5 km/s New Shepard Source: Blue Origin Less dry mass to be launched from Earth -> impact magnified Falcon 9 Source: SpaceX
www.dlr.de Chart 6 RLRV design Identified key technologies to improve the efficiency of Moon transportation systems: Expander cycle LOx/LH2 engine ISPP Reusability Influencing parameters Origin of the propellant: Earth vs Moon Rendezvous position: LLO vs EML1 First step: Design of a reusable lunar single stage to orbit vehicle RLRV: Reusable Lunar Resupply Vehicle Earth Moon system Source: space.stackexchange.com ΔV between Earth surface [km/s] ΔV between Moon surface [km/s] and LEO 9.5 6.3 and EML1 13.3 2.5 and LLO 13.8 1.9
www.dlr.de Chart 7 RLRV design Engine design and optimization of the thrust level Influence on the V Burning duration: influences the number of reuse Throttling: for soft landing Selected thrust 100 kn Re-ignition: influences the number of reuse ΔV [m/s] Descent from LLO (100km) Descent from EML1 3000 2800 2600 2400 2200 2000 1800 1600 Ascent to LLO (100km) Ascent to EML1 0 0.2 0.4 0.6 0.8 T/W [-] Payload mass wrt. highest [%] 102 100 98 96 94 92 90 88 86 84 82 80 15% 20% 25% historic vehicles 78 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 T/W [-] Value Pcc [bar] 60 Mixture ratio [-] 6 Expansion ratio [-] 100 Nominal thrust [kn] 100 Vacuum Isp [s] 452.5 Nozzle exit pressure [bar] 0.039 Mass [kg] 206 Life expectancy [s] 3500 Throttling range [%] 8 to100
www.dlr.de Chart 8 RLRV design Structural design and analysis Separated tanks Reduction of heat flux Shell design Sizing load case: launch from Earth Pressurization system and RCS Helium and hydrazine based systems are life limiting for the RLRV Integrated Vehicle Fluids or APU: power + pressurisation Low pressure LOx/LH2 thrusters fed from main tank for RCS Structural index [-] 0.28 0.26 0.24 0.22 0.2 0.18 d2d2 d3d2.6 d3d3 d4d3 0.16 7000 9000 11000 13000 15000 17000 19000 21000 Propellant loading [kg]
www.dlr.de Chart 9 RLRV design Main payload interface H20 LH2 tank Intertank structure H20 LOx tank Secondary payload Main engine Wheeled landing legs
www.dlr.de Chart 10 Operations, missions and performances Orbital Mission 0 (reference): land a 10 ton payload Mission 1: minimum prop to land Mission 2a: maximum P/L to LLO or EML1 Mission 2b: maximum prop mass to LLO or EML1 Mission 3: maximum P/L to the surface Suborbital Mission 4: flight to the pole with min. prop mass Mission 5a: maximum prop mass from the pole Mission 5b: maximum P/L from the pole Large flexibility allowed by reusability Mass propellant / payload [kg] 30000 25000 20000 15000 10000 5000 0 LLO EML1 suborbital Mission
www.dlr.de Chart 11 Comparison with the Apollo LM Apollo LM 16.5 tons (ascent module 4.8 tons) 800 700 600 ISPP plant Vehicle Payload RLRV Require first 2 RLRV to establish a 20 ton ISPP plant Engine life time: 4000 s Different payloads considered 48 tons (exactly 10 LM) 100 tons 175 tons (ROBEX habitat) Mass to LLO/EML1 [Mg] 500 400 300 200 100 0 48 tons payload 100 tons payload 175 tons payload LM RLRV LLO RLRV EML1 LM RLRV LLO RLRV EML1 LM RLRV LLO RLRV EML1
www.dlr.de Chart 12 Conclusions Recent developments make LOx/LH2 expander engine, ISPP and reusability interesting solutions to build effective, flexible Moon transportation systems. Their combination can magnify the benefit of each taken alone Reusability can allow cost reduction but also a large flexibility The proposed RLRV concept seems superior to Apollo type vehicles to deploy large infrastructures on the Moon Reusability can be applied to the other elements of the transportation chain for further improvements
Questions? www.dlr.de Chart 13 > Etienne Dumont> SART > 2016_09_09 Madmen open the paths which are later traversed by the wise. (C. Dossi)