Inputs on HPM EPS, SEP Stage Block II configuration, and comments on 10/2 presentation package Tim Sarver-Verhey 10/1/2001

HPM Power System - Update Power system performance & characteristics 2/16/2019 GRC/TRSV

CTM Power System - Update Power system performance & characteristics 2/16/2019 GRC/TRSV

SEP Stage - Orbit Transfer Performance Transfer from ISS orbit to 320,000 km @ 19.5 ° Assumed low-thrust spiral Inclination change performed throughout spiral Total Vehicle Mass 59.7 MT 36.3 MT fixed payload assumed (31.1 Chem load + 5.2 MT HPM dry mass) 16.3 MT for return trip: SEP Stage + Empty HPM Propellant Mass 12.2 MT for out-bound Trip Time 272 days out-bound 2/16/2019 GRC/TRSV

SEP Stage - System Summary Thrusters 9 Gridded ion engines required 1 spare included PPUs on deployed palette PV Arrays 2 Square rigger wings employed Array area = 2700 m2 Power produced = 450 kW Assume 5 kW for system power Power density = 167 W/m2 Arrays fixed on base palette HPM/Base to fly solar inertial Articulated Boom 20 m coilable main boom section 2 rigid segments to extend thruster reach SEP System “Dry” Mass = 11.2 MT Includes 2 MT of xenon on-board 2/16/2019 GRC/TRSV Mass Breakdown

SEP Stage - Detailed Mass Breakdown Radiator area: 30.2 m2 Radiator area: 24.6 m2 2/16/2019 GRC/TRSV

Hybrid Propellant Module (HPM) Mass & Technology Summary 3939 Calculated Dry Mass 165 Dry Mass Margin 943 Shielding 1314 Structures 4,104 Dry Mass Target Mass 1,089 Propellant Management 305 Power 234 Thermal 42 Command/Control/Comm 12 Navigation/Attitude Control Calculated Mass (kg) Subsystem HPM Advanced Technology Requirements Integrated Flywheel Energy Storage System - Combination energy storage and attitude control Advanced Triple Junction Crystalline Solar Cells >30% efficiency Zero Boil-Off System - Cryogenic propellant storage system (up to 10 years of storage without boil-off) Integrated Primary Multifunction Structure & Meteoroid and Orbital Debris Shield - Non-metallic hybrids to maximize radiation protection Autonomous Operations including Rendezvous and Docking On-Orbit Cryogenic Fluid Transfer Lightweight Composite Cryogenic Propellant Storage Tanks Graphitic Foams and Syntactic Metal Foams Carbon-Carbon Composite Radiators 2/16/2019 GRC/TRSV

Crew Transfer Vehicle (CTV) Mass & Technology Summary Technologies Currently Used in CTV Advanced Triple Junction Crystalline Solar Cells Provide >500 W/kg (blanket) >30% efficiency or Integrated Primary Multifunction Structure & Meteoroid and Orbital Debris Shield Non-metallic hybrids to maximize radiation protection Autonomous Operations including Rendezvous and Docking Lightweight Composite Cryogenic Storage Tanks Graphitic Foams and Syntactic Metal Foams Carbon-Carbon Composite Radiators Advanced ECLSS CO2 Removal System 5.5m Graphic deleted Mass of Full (CTV) = 5282 kg 2/16/2019 GRC/TRSV

Solar Electric Propulsion Module (SEP) Mass & Technology Summary Photovoltaic Arrays: 2 square-rigger style wings (rad hard as possible) Thin film cells, Array area = 2700 m2, Power produced = 450 kW Thrusters: 8 Gridded Ion Engines, operating at 50 kW Xenon, 3,300 s Isp, 2.0 N thrust per engine, 15 khours lifetime (Minimum) Articulated boom for thrust vectoring Base Palette containing Extra Xenon for free-flying operation Arrays mounts Power processing Reaction Control system Attitude Control system HPM docking & Fluid Transfer interfaces Mass of Full (SEP) =11,000 kg (includes 2000 KG of Xenon) 2/16/2019 GRC/TRSV

Overall Technology Summary Key Technologies Integrated flywheel energy storage system Advanced triple junction crystalline solar cells Zero Boil-Off (ZBO) system Integrated primary multifunction structure, radiation & meteoroid and orbital debris shielding Autonomous operations including rendezvous and docking On-orbit cryogenic fluid transfer Lightweight cryogenic propellant tanks Graphitic foams and syntactic metal foams Carbon-carbon composite radiators High performance, high cycle life LH2/LOX main engine Integrated GH2/GOX Reaction Control System (RCS) Advanced ECLSS CO2 removal system Large deployable thin film arrays Gridded ion engines HPM CTV CTM SEP 3-axis control possible 3-axis control 3-axis control > 40% eff > 40% eff > 40% eff 20% eff Multistage NA NA NA Also provides Also provides Also provides Yes thermal radiation thermal Insulation shielding insulation MANS/AFF MANS/AFF MANS/AFF MANS/AFF LH2/LO2/Xenon NA LH2/LO2/Xenon Xenon/GH2/GO2 Composite NA Aluminum Composite YES YES YES YES NA NA 50-100 Starts NA 0.995 reliability NA NA Yes YES NA YES NA NA NA NA NA 167W/m**2, rad res’t. NA NA NA Hi-power, >15kh life 2/16/2019 GRC/TRSV

Summary & Forward Work The HPM concept in the OASIS framework could reduce costs and enhance mission robustness across a wide spectrum of future space activities. Economic sensitivities for NASA and commercial applications have indicated that inexpensive launch of propellant on the order of $1000/kg is the threshold for making a space based transportation infrastructure viable. Solar Electric Propulsion technologies (high performance, radiation resistant arrays, long-lived high performance gridded ion engines, large deployable systems) present significant technology development challenges, which can be achieved with sufficient resources. Pat: folks here aren’t too comfortable having SEP called out as tall pole (yet again), in particular since many other elements of this program are little more than paper studies (launch vehicles and their costs, Gateway/OASIS, light-weight cryo-tanks, etc.) Can this statement be further revised so that SEP doesn’t appear to be the lone ‘bad guy’ for this mission? Follow-on activities under RASC have been proposed for FY02: Refined commercial and DOD applications Increased detail assessments for other supporting concepts (SEP, CTM, CTV, etc) Applications beyond the Earth-Moon system 2/16/2019 GRC/TRSV