Lunar L 1 Gateway SEP Design Briefing Gateway

Lunar L 1 Gateway & SEP Design Briefing Gateway Element Lead: Frank Lin Lead Systems Engineer: Jim Geffre JSC Gateway Design Team SEP 11/1/2020 NASA GRC SEP Team 11/2/01 1

Briefing Objectives • Review work done to date by JSC Advanced Design Team on Gateway architecture – Focus on design of Gateway Element • Review work done to date by NASA GRC on Gateway architecture – Focus on design of Solar Electric Propulsion (SEP) system 11/1/2020 2

Briefing Outline • Gateway Architecture Overview • Gateway Mission Overview • Requirement Development • Mission Requirements and Constraints • Functional Allocation Matrix (FAM), N 2 Charts, Sub-system Requirements • Gateway Sub-Systems Descriptions • Preliminary Hazard and Reliability Analysis • Future Technology Investments • Open Issues/Forward Work • Solar Electric Propulsion 11/1/2020 3

Gateway Architecture “Earth’s Neighborhood” Crew departs from and returns to ISS GPS Constellation L 1 Gateway Lunar Habitat Lunar Lander Crew Transfer Vehicle • Transports crew between ISS and Gateway • Nominal aerocapture to ISS, or direct Earth return contingency capability 11/1/2020 L 1 Gateway • “Gateway” to the Lunar surface • Outpost for staging missions to Moon, Mars and telescope construction • Crew safe haven Lunar Lander • Transports crew between Gateway and Lunar Surface • 9 day mission (3 days on Lunar surface) Lunar Habitat • 30 -day surface habitat placed at Lunar South Pole • Enables extended-duration surface exploration and ops studies 4

LEO Operations Gateway Mission Profile Launch Gateway on DELTA IV-H Activate Critical Systems, Inflate & Checkout Gateway Launch Shuttle with Gateway Outfitting Crew Launch SEP on DELTA IV-H Shuttle Rendezvous and Docking with Gateway Outfit & Checkout Gateway SEP Autonomously Dock with Gateway Autonomously Deploy SEP Solar Arrays Gateway and SEP spiral to LL 1 (unmanned) LL 1 Operations Up to 15 days* 11/1/2020 Lunar Surface Mission Crew Arrives at Gateway in CTV Crew Returns to Earth in CTV 30 days Telescope Mission Deliver Lunar Lander to Gateway (unmanned) Gateway Logistics Resupply / Cargo Delivery (unmanned) 30 days Science Mission *Reflects crew time spent in Gateway 5

Gateway Mission Flow Chart Launched on Delta IV Stable on-orbit config Y Inflate, activate, and checkout in LEO All systems go? Send replacement/rep air mission on Shuttle N N Y Done Fully deploy SEP arrays Dock Y successful? SEP Rndz/ dock with Gateway at LEO Shuttle outfitting in LEO, final Checkout (detailed list TBD) All systems go? Repair successful? N Y Partial SEP array deploy Launch SEP stage Y Go/No go for TLI? Y Gateway go/no go for SEP launch? TLI? N N Y Shuttle returns Attempt repair on later Shuttle mission if possible N Stabilize Gateway and SEP Stack go for TLI ? N N Y Transit from LEO to LL 1 11/1/2020 SEP stage undocks for return Gateway uses chem prop system for separation and L 1 insertion Config Gateway for stable L 1 ops * Refer to Lunar L 1 Architecture Operational Events Flow Chart * Lunar mission Telescope mission Lunar lander CTV Telescope arrives CTV 6

Requirements and Constraints Top Level Requirements • Stage telescope construction and lunar surface missions from Gateway – Two telescope construction missions per year – Two lunar surface excursions per year • • • Support crew of four Design lifetime of 15 years Simultaneously support three docked vehicles (CTV, Lunar Lander, Logistics Module) Provide EVA capability for nominal operations Maintain position at lunar L 1 Lagrange point Autonomous transfer from low-Earth orbit to lunar L 1 Design Goals and Constraints • • • 11/1/2020 Incorporate inflatable technology Delivery to lunar L 1 via solar electric propulsion Crew safety is highest priority Maximum system technology demonstration capability Maximize use of technologies viable for future human space exploration 7

Gateway Requirement Development Process FAM • Defines Gateway functions for each mission phase • Identifies Gateway Sub-systems for each mission phase N 2 Chart • Defines System interface connectivity for Gateway by mission phase • Defines type and disposition of system interfaces Sub-system Requirements • Defines required systems for each mission phase 11/1/2020 8

Gateway Element Summary • • Element Design Lifetime: 15 yrs Element Mass: – – Launch: 22, 827 kg Outfitting: 588 kg Post-outfitting: 23, 415 kg Resupply mass/Volume: • • Element Volume: – Launch: – Operational: Power provided: – – PV Array: Energy Storage: • • • Batteries Flywheel Radiators (3) ACS 805 kg / 3. 878 m 3 2, 824 kg / 7. 587 m 3 Cupola 145 m 3 275 m 3 RCS jets Prop & ECLS tanks 12 k. W Nom/14. 4 k. W Peak 71 k. W-h 20 k. W-h EVA Work Platform/ Telescope Assembly Site P/V Arrays (2) Support Missions: – – – • • 6 -months: 24 -months: Inflatable Airlock (4) Outfitting at LEO: HF&H consumables: ECLSS/Prop: Estimate Element Cost: System Reliability: 11/1/2020 One mission/architecture Two missions/year One mission/two years RMS XX M 72% 9

Gateway Configurations Launch Configuration Lunar Operations Configuration 11/1/2020 LEO, Transit, L 1 Stand-by Configuration Telescope Operations Configuration 10

Gateway Systems • Attitude Control System (ACS) • Avionics • ECLSS • EVA • Human Factors & Habitability (HF&H) • Power • Propulsion • Robotics • Structures • Thermal Control • Mission Operations • Mission Success 11/1/2020 11

Attitude Control System Design Summary System Requirements: • Maintain Solar Inertial Attitude for Gateway in low-Earth orbit and at Lunar L 1 • Provide 1, 000 N-m-s of Momentum Storage • Provide 20, 000 W-hr of Energy Storage Assumptions Made: • Momentum storage requirements are equivalent to NGST • Flywheel system axis must be aligned with one of the Gateway’s body axes Concept Trades Considered: • Flywheels • Control Moment Gyros • Chemical RCS Selected Technologies: • Integrated Power and Attitude Control System (IPACS) Flywheels Rationale: The flywheel system offers the potential for a coupled energy storage and attitude control capability, and is the least mass alternative. A CMG system would require a larger lithium-ion battery system to accommodate the extra 20 k. W-hr of energy storage. Chemical RCS requires a large propellant load to handle the attitude control needs for 15 years. 11/1/2020 12

Attitude Control System Design Summary System Specification: • • • Physical dimensions: Mass: 318 kg Provide 70 k. We peak power to user TRL 3 Volume: 0. 288 m 3 Issues and Concerns • None Forward Work • Determine flywheel system reliability & lifetime IPACS Flywheel System 11/1/2020 13

Avionics System Design Summary System Requirement • Provide guidance, navigation, control, communications, and health monitoring of Gateway Assumptions Made • Communications would follow proposed Ka-band upgrade and operate in the 32 ghz range • UHF would be used for space-to-space communication between vehicles • Flight Computer System would be a quad-redundant system based on the X-38 Fault Tolerant Processor model • The flight computer, itself, would be based on the Universal Mini-Controller (UMC) • Flight Computers would be distributed so that they could also collect data from subsystems near their respective locations • Wiring would include a combination of fiber optics, wireless, and parasitic use of the power buses where applicable, optimally selected to minimize mass and maximize reliability Concept Trades Considered • NA 11/1/2020 14

Avionics System Design Summary System Specification • Mass is 251 kg • Total Volume Required: 1. 0 m 3 • Overall Sub-system TRL Level: 6 Issues and Concerns • None Forward Work • None 11/1/2020 15

Avionics System Design Summary Ka-band Antennae Gateway Avionics Architecture Omni Stellar Attitude Sensor Video System PAU Antenna Switch Displays SSVR (UHF) Digital Voice PAU Diplexer Ka. Band Data Buses Flight computers Sensor Data Flight Computer with Data Acquisition & Control Power Amplifier PAU INS Crew Interface - Hand Controllers - Switches HDR Low PAU Noise LDR Amplifier PAU Transponder Intercomputer Bus HDR and LDR Data 11/1/2020 16

ECLSS System Design Summary System Requirement • Control cabin temperature, humidity (NASA-STD-3000), and pressure (select at 9 psia) • Provide crew consumables (O 2, N 2, H 2 O) for cabin, airlock and EVA • Provide closed air, water recovery and waste management systems to minimize re-supply Assumptions Made • Two-year re-supply period • Crew daily O 2 consumption rate - 0. 84 kg/person/day • Crew drinking and food preparation – 2. 8 kg/person/day, hygiene, 6. 8 kg/person/day • No dishwasher, no laundry, no salad machine Concept Trades Considered • High pressure vs. cryogenic N 2 and O 2 storage • CO 2 removal technology: 4 x BMS vs. solid amine • Biological water recovery technology (BWR) vs. Vapor Phase Catalytic Ammonia Removal technology (VPCAR) Selected Technologies • Cryogenic w/ High pressure for inflation • 4 x BMS CO 2 removal system • VPCAR 11/1/2020 Rationale: Cryogenic system has less mass. High pressure tanks for initial Gateway inflation for shorter inflation time. Rationale: relative mature close CO 2 removal system Rationale: Mass, volume and power benefits. Shorter turn-around time. Restart ability. 17

ECLSS System Design Summary System Specification • ECLSS System Mass: 2851 kg • Dry Mass: 2174 kg • Fluid Mass: 677 kg • ECLSS System Volume: 15. 9 m 3 • TRL Level: • CO 2 removal 9 • Fire detection and suppression 9 • Oxygen generation system 6 • Vapor Phase Catalytic Ammonia Removal (VPCAR) 4 • CO 2 reduction system 6 • Water recovery from brines (air evaporation system) 6 • CO 2 compressor 3 • WRS product water post processor (ion-exchange beds) 6 • Trace contaminant control 4 • Solid Waste Processing (Lyophlilization water recovery) 3 Issues and Concerns • NASA-STD-3000 set long-term mission spacecraft pressure at 14. 5 – 14. 9 psia. Forward Work • Report 11/1/2020 18

ECLSS System Design Summary ECLSS Water Recovery System Block Diagram Respiration, condensate Urine + flush water Hygiene wastewater Potable Water Tank VPCAR Food preparation 45 kg/day brine Post processor Air Evaporation System (AES) vacuum Cond HX ECLSS Air Revitalization System Block Diagram Cabin at 9. 0 psia O 2 30% N 2 70% 4 BMS CO 2 TCCS Waste Processing System O 2 from propulsion cryogenic storage 11/1/2020 Sabatier CO 2 reduction subsystem air H 2 O O 2 Tank N 2 Tank High Pressure O 2 Gen. subsystem CH 4, CO 2, H 2 vent H 2 Air leaks Water from water recovery system 19

EVA System Design Summary System Requirement • Store 4 Space Suits from CTV • Support Four six month mission phases prior to resupply • 10 EVAs (8 hr) for Telescope mission for four missions • Gateway maintenance at one EVA per six month mission • Total of 84 4 hr EVAs prior to resupply Assumptions Made • 10 EVAs for Telescope mission • 1 EVA for Gateway maintenance per six month mission • Two tool boxes for Telescope assembly Concept Trades Considered • Recharge system to recharge 3000 psi PLSS Oxygen tanks from low pressure cryo tanks • Chose thermal compression to 850 psi, mechanical compression from 850 psi to 3000 psi, (ORCA), ECLSS emergency repress tank used as accumulator for rapid refill then recharged using compressor. System Specification • Space Suits • Vehicle Support for EVA • EVA Translation Aids • EVA Tools • Airlock 11/1/2020 Dry Mass Volume Minimum TRL 636 kg 212 kg 123 kg 132 kg 433 kg 3. 62 m 3 0. 34 m 3 3. 36 m 3 0. 2 m 3 8. 18 m 3 TRL 2 TRL 3 TRL 9 TRL 3 20

EVA System Design Summary Issues and Concerns • Lack of Technology Development Funds to raise low TRL items within schedule needs Forward Work • • Light weight PLSS Recharge system to recharge 3000 psi PLSS tanks from 150 psi lox supply Transvector Trim cooler Purge Valve Fan Swing Bed CO 2 & Humidity Remover Accumulator Battery Pump Radiator 11/1/2020 Comfort Heater C&W H 2 O Evaporator Lunar Space Suit Schematics 21

Gateway EVA System Block Diagram PLSS ECLSS High Pressure O 2 Tank Oxygen Compressor 800 to 3000 psi Storage 850 psi Relief Valve Flexible Umbilical Cryo Coolers Q = 90 BTU/lb LOX at sub critical pressures ECLSS use Gateway Space Suit Oxygen Recharger Schematic ECLSS top off configuration 11/1/2020 22

Habitability and Human Factors (HF&H) System Design Summary System Requirement • Provide consumables for 60 days • Provide a minimum habitable volume of 60 m 3 (15 m 3/person) • Comply with MSIS/NASA-STD-3000 Assumptions Made • Maximum contingency duration of Gateway use is 60 days, with a 25 -day crewed maximum nominal mission phase. • Gateway station provides an “oasis” in terms of living environment Concept Trades Considered • Crew Quarters: Dorm Style v. Private Quarters • Waste Collection Facility: Plumbed v. self-contained facility v. bags only • Hygiene Facility: Partial-body cleansing v. Full-body cleansing • Medical Equipment: Med kit only v. nominal mission life support v. contingency scenario life support • Exercise Capability: No exercise v. limited resistive v. cardio only v. resistive and cardio training • Food System: Shuttle food system (pure-ambient) v. Conditioned food • Clothing: Clothing as consumable v. washer/dryer • Acoustics: Acoustic abatement throughout module v. Acoustic abatement at CQ and equipment room hatch only 11/1/2020 23

Habitability and Human Factors (HF&H) System Design Summary System Specification • Mass: 2507. 48 kg • Volume: • HF&H equipment: 15. 04 m 3 • Habitable volume: 200 m 3 • TRL Level: 8 Issues and Concerns • Conditioned food: This is a nutritional need for the health of the crew, but is currently not considered feasible because of infrequent resupply missions to the Gateway/radiation issues • Windows: Additional viewing windows (for scientific observation and recreation) are preferable in the Gateway • Resupply: Logistics of resupply of crew-preference and crew-specific items (e. g. clothing, food, hygiene consumables) needs to be more well-defined with consideration for radiation exposure Forward Work • Research possible HW mass losses between now (current Station hardware) and fly date • Double check depressurization compatibility of HW and supplies • Continue modifying detailed layout • Research exercise technologies • Research food technologies • Investigate lighting effects and simulated windows 11/1/2020 24

Habitability and Human Factors (HF&H) Cabin Layout SMF HDTV Exercise Facility CQ HF WCF 11/1/2020 Stowage CQ Galley Workstations CQ CQ CQ = Crew Quarters HF = Hygiene Facility WCF = Waste Collection Facility SMF = Space Medical Facility HDTV = High 25 Definition TV

EPS System Design Summary System Requirements • Provide 1 k. W (Peak) during ascent, orbit injection and deployment for Gateway survival and initial on-board operations. • Provide 2 KW during LEO operations (90 min. orbit with 45 min. eclipse time) prior to rendezvous with SEP. • Provide continuous 12 KW while at LL 1 with an energy storage capability to compensate during the 13 hr maximum eclipse time every 6 weeks for the entire Gateway life cycle of 15 years. Assumptions Made: • Power generation and storage sized to include 30% contingency and 20% additional mass for secondary support structure. • It assumed that the overall EPS system is about 70% efficient (user power/power generated) • Arrays 1 fault tolerant, but rest of H/W 2 fault tolerant (ring bus architecture assumed). – High voltage DC to be provided by array and batteries and distributed within the Primary Distribution System. – Secondary Distribution System is 115 Vac, 3Ø, 400 Hz – Two Tertiary Distribution Systems included: 28 Vdc and 110 Vac, 1Ø, 60 Hz. 11/1/2020 26

EPS System Design Summary Concept Trades Considered: • • • Ultraflex vs. Inflatable PV Array Thin-film vs. Fiber Li-Ion Battery 28 Vdc vs. 115 Vac, 3Ø, 400 Hz Selected Technologies: • Ultraflex, Fiber Li-Ion integrated into structure, 115 AC, 3Ø, 400 Hz Rationale: Lower mass and design simplicity System Specification: • • Physical dimensions: Mass: 1, 335 kg Volume: 27 m 3 Provide 12 k. W nominal with 14. 4 k. W Peak to user Arrays capable of 20. 7 k. We TRL • • • PV Arrays Deployment Truss Battery Wiring Harness PMAD 7 6 2 9 6 Issues and Concerns • • Development of 400 Hz RPC Box Development of Fiber Li-Ion Battery System • Full assessment of the Fiber Li-Ion battery capability and integration into vehicle structure. Forward Work 11/1/2020 27

EPS System Architecture Bus A Fiber Li- Ultra. Fle x Array Unit #1 Bus C Representation of a Single String of the “Inner Loop” Power Distribution System Inverter 155 Vdc Inverter 115 Vac, 3Ø, 400 Hz RPC 115 Vac, 3Ø, 400 Hz to 28 Vdc Converter RPC Tertiary Distributi on System RPC Secondar y Distributi on System 110 Vac, 1Ø, 400 to 60 Hz Frequency Converter Cha rge / Charge / Discharg Dis cha e Unit #1 rge Unit #1 Fib Ion er Fabric Li. Section Ion Fa bri Relays c Se RPC Box cti INVERTER on RPC Box Ultra. Fle x Array Unit #2 INVERTER Fiber Li-Ion Cha Fabric rge Section / Charge / Discharg cha rge e Unit #2 Relays Cha Power Bus #3 Power Busrge #2 Power Bus/ #1 Dis cha rge Unit #3 Fiber Li. Ion Fabric Section Charge / Discharge Unit #3 EPS System Block Diagram Primary Distribution System 11/1/2020 28

Propulsion System Design Summary System Requirement: • Provide Gateway vehicle with approx. 50 m/s delta V per year for station keeping Assumptions Made: • Propellant resupplied once every two years • Vehicle lifetime 15 years • Propulsion system for station keeping only, no ACS • Book-keep ECLSS and EVA O 2 (491 kg) Concept Trades Considered: • Propellant selection -Tridyne, Hydrazine, NTO/MMH, LOx/CH 4 • System size vs. regularity of resupply Concept(s) Selected: • 12 x 110 N LOx/CH 4 engines Rationale: Mass/volume savings, non corrosive exhaust products System Specification: • Mass: 176 (dry) kg. 1, 444 (total) kg. • Dimensions/Volume: Approx. 1. 23 m 3 tank 11/1/2020 29

Propulsion Preliminary Design Summary Issues and Concerns: • Thruster placement due to the nature of the inflatable structure design and plume impingement on solar arrays TRL: • Engines 4 • Cryocoolers 4 Forward Work: • None 11/1/2020 30

Propulsion Preliminary Design Summary Integrated LO 2/LCH 4 Gateway Propulsion Schematic 110 N RCS Engines 322 s Isp 3. 8 MR TVS

Robotics System Design Summary System Requirement • Support EVA activities and maintenance, inspection and mobility of both intra- and extravehicular systems Assumptions Made • Large arm needed for gross payload manipulation • Dexterous robot needed for human-equivalent manipulation • Will use automated “smart systems” where appropriate Concept Trades Considered • No tasks or requirements were identified that required a trade study System Specification • Robotic Manipulator System • Mass: 543 kg • Dimensions/Volume: Arm- 15. 2 m x Æ. 33 m RWS Stowed- ISPR 1. 01 m x 1. 07 m x 1. 98 m • TRL Level: Arm- 9 RWS- 8 • Robonaut • Mass: 136 kg • Dimensions/Volume: . 71 m³ • TRL Level: 5 11/1/2020 32

Robotics System Design Summary Issues and Concerns • Current work reflects generic robotic requirements defined as: • Gross payload manipulation • Human-equivalent manipulation Forward Work • Continue development of Robonaut to increase autonomy and functionality • Define and identify the robotic requirements associated with telescope construction • Size RMS based on telescope construction requirements 11/1/2020 33

Robotics System Design Summary Available Solutions 11/1/2020 34

Structures System Design Summary Structural Requirements • Interface to Delta IV Heavy • Support crew of 4 for 25 days • Provide docking mechanisms for CTV and Lunar Lander • Provide worksites for constructing/assembling telescope • Provide structure to mount other systems within primary structure Assumptions Made • 6 g axial and 2. 5 g radial launch loads • 9 psi nominal internal pressure Concept Trades Considered • Hardshell vs. Inflatable vs. Hybrid Gateway Structure • Hybrid structure encouraged by architecture team for future applicability to future exploration missions System Specification • Gateway total Mass: • Overall length: • Hard shell Dia. : • Inflatable Dia: 11/1/2020 7354 kg 9. 3 m 4 m 9 m 35

Structures System Design Summary 11/1/2020 36

Structures System Design Summary Issues and Concerns • Radiation protection not incorporated into design due to unavailable design support from SF 2 • Material properties for the mission at L 1 are assumed to be acceptable at EOL for the mission duration. • Procedure for replacing MM/OD shielding on inflatable not identified Forward Work • Incorporating radiation protection • More detailed design and analysis of primary structure 11/1/2020 37

TCS System Design Summary System Requirement • Collect, Transport, and Reject 15. 6 k. W to space • Provide heaters to maintain low temperature limits of the Gateway shell Assumptions Made • Radiators are freeze tolerant • All radiator panels see deep space environment • Air distribution over the internal inflatable wall prevents condensation (no heaters on fabric) Concept Trades Considered • Single Loop vs. Dual Loops • TCS working fluid types • Flow Through Radiators vs. Heat Pipe Radiators • Number of Radiator panels Concepts Selected • Single loop • 60% propylene glycol/40 % water • Flow through radiators • Three radiator panels 11/1/2020 Rationale: Less hardware, no toxic fluid needed Freeze tolerance, safer working fluid Lower mass Redundancy 38

TCS System Design Summary System Specification • 663 kg Total Mass • 115. 4 kg Fluid mass, 547. 6 kg Dry mass • 3. 39 m 3 Total Volume • 0. 84 m 3 ETCS & Radiators, 2. 56 m 3 Multi-layer Insulation • TRL levels • Flow through, flexible, freeze tolerant radiators: 4 -5 • All other TCS components: 9 Issues and Concerns • Working fluid concerns regarding freeze tolerance • Will single loop architecture function in the environment • Inflatable inner wall air flow • Exposure of equipment in inflatable section to space vacuum • Equipment operation at 9. 0 psia operating pressure Forward Work • More detailed analysis to characterize thermal environment • Evaluate test data for flexible radiators and heat pipes • Investigate attachment methods for flexible radiator to inflatable shell 11/1/2020 39

TCS System Block Diagram Gateway Thermal Control System Schematic Flexible Radiator bypass External Coldplates Redundant Pumps Condensing HX 11/1/2020 Internal Coldplates 40

Mission Operations Assessment • Gateway checkout in LEO – Critical Gateway systems to be checked out prior to Shuttle outfitting mission • • – Remaining systems will be checked out during Shuttle outfitting mission and prior to transfer to Lunar L 1 • • • Pressure vessel integrity Life support system Electrical power system GNC/attitude control system Data processing Communication system Thermal control system Robotics Waste collection system HF&H Inflatable airlocks LEO Outfitting Mission – Pressurized cargo carriers considered: • – MPLM, Space. Hab module Recommendation • Modify double Space. Hab with IBDM • Launch Gateway SRMS on sill longeron and relocated using SRMS – 11/1/2020 Zero Shuttle modification required 41

Mission Operations Assessment • Gateway Resupply strategy – Immediate resupply • CTV to carry immediate crew resupply items – Limited volume and mass items • CTV to leave contingency food on Gateway • CTV to swap out shelf life sensitive items that are common on CTV and Gateway – Medical supplies, food, etc. – Short term resupply • Once every six months • Use Lunar Lander habitable volume for stowing resupply items • Resupply items include: Food, clothing, medical supplies (items that are less time and radiation sensitive), misc. crew supplies, etc. – Long term resupply • Once every two years • Require a module capable of carrying pressurized and unpressurized cargo – Identified as a new element to the Gateway architecture. • Resupply items include: Station keeping propellant, ECLSS system consumables, large ORUs and tools, experiments, etc. 11/1/2020 42

Safety and Mission Assurance Strategies for Human Exploration – Gateway II PHA Summary Category Eliminated Controlled Accepted Risk Open Hazardous Causes Identified 0 77 0 2 Open Work from Hazard Analysis • An analysis of the radiation protection of the vehicle's final configuration should be done. This will affect the hazard controls for two conditions identified concerning excessive radiation in the crew habitable environment. 11/1/2020 43

Gateway Sparing Analysis for Avionics Subsystem 11/1/2020 44

Gateway, SEP and Suit Reliability 11/1/2020 45

Conclusions System Reliability & Sparing • Reliability Block Diagram Analysis predicted a Gateway reliability with no repair of approximately 72%. This reliability is associated with mission success modeling of all the supporting subsystems which includes EVA suits for telescope construction. • Sparing requirements for one re-supply cycle (10, 225 hours) of the Gateway will be significant given the reliabilities of the modeled subsystems. Crew Safety • The PHA has documented the subsystem design mitigations controlling the hazards identified. • All subsystems will meet fail-op/fail-safe requirements as specified in the Human Ratings Requirements with the option of the LTV ticket back to LEO. This however only applies to crew safety and not mission success. • Open Work: Analysis to evaluate the inherent radiation protection of the Gateway design 11/1/2020 46

Gateway Mass Summary 11/1/2020 Mass Limit: 35, 400 kg (Delta IV Heavy Capability) 47

Gateway Power Profile 11/1/2020 48

Gateway Cost Summary Gateway $ 979. 1 M ACS $ 31. 3 Thermal Control $ 62. 2 M Avionics $ 50. 8 d e at EVA $ 5. 1 Human Factors & Habitability $ 0. 45 M B o T Power $ 59. 1 M U e d p Robotics $ 104 M Propulsion $ 87. 9 M STR & MECH $ 453. 8 M Systems Integration & Test $ 59. 2 M ECLSS $ 130. 2 M PRICE –H Cost Analysis Assumptions • All masses and volumes are entered in metric units • Development start date(DSTART)=1/02 • Cost estimates are shown in 2001 dollars • Completion date of first prototype (DFPRO)=4/07 • Cost includes hardware development and manufacturing • Completion date of last proto/flight unit (DLPRO)=4/09 • Assume three prototype for each system 2 prototype / flight unit • Twenty percent program reserve added to PRICE-H cost figures • Year of technology (YRTECH) value is 2005 • Does not include recurring or operations costs 11/1/2020 49

Future Technology Investments • ACS – Flywheel technology • ECLSS – Vapor Phase Catalytic Ammonia Removal (VPCAR) – Lyophilization Water Recovery • EVA – Inflatable Airlock – Next Generation Space Suit • EPS – Fiber Li-Ion Batteries • Propulsion – Cryo Cooler • Structures – Radiation Protection Materials and Methods – MMOD Protection Materials and Methods 11/1/2020 50

Open Issues / Forward Work • No radiation protection analysis • Unknown long-duration material degradation in Lunar L 1 environment • Unknown effects of multiple spirals through Van Allen radiation belts • Need a detailed orbit propagation to determine exact stationkeeping requirements • Resupply vehicle design unknown • Gateway trash disposal • Need better definition of telescope mission requirements to complete design of Gateway systems • Examine rigid structure design for comparison to current inflatable concept 11/1/2020 51

Lunar L 1 Gateway Mission Architecture Solar Electric Propulsion (SEP) Stage Preliminary Configuration Summary of Oct. 12, 2001 Presentation NASA Glenn Tim Sarver-Verhey Tom Kerslake Len Dudzinski Leon Gefert Janice Romanin Robert Sefcik Dave Hoffman October 25, 2001 11/1/2020 52

Gateway Solar Electric Propulsion (SEP) Stage System Requirements • • • Launch on a Delta IV Heavy or Shuttle to 400 km 28. 5° LEO[1] – “Exploration Class” Delta IV Heavy presumed - 35 MT to LEO 30 MT payloads [2] – Lander & Habitat mass 35 MT Total SEP Stage Mass Limit – Derived from requirements #1 Maximum 6 -month LEO-to-Lunar L 1 trip time [2] – A 30 MT Lander must be delivered to Lunar L 1 every 6 months TRL 6 by 2005 for all systems technologies[1] Assumptions Made • • • Structural & electrical interfaces with SEP stage payloads – 5 k. W power transfer from SEP stage to Gateway Habitat payload – 12 m maximum Gateway Habitat payload diameter x 10 m length SEP stage housekeeping power 1% of total power required 20% SEP stage dry mass margin Sources: [1]“Lunar L 1 Gateway Introduction Package”, J. Geffre, 7/9/01 [2]“Lunar L 1 Architecture Timeline”, email from J. Geffre, 7/27/01 11/1/2020 53

Gateway Solar Electric Propulsion (SEP) Stage Primary Issues/Trades Considered • What is the power required vs. trip time? – To deliver 30 MT to L 1 in 180 days, a 584 k. W SEP stage with 15. 0 MT dry mass and 20. 0 MT of xenon propellant is required - assuming 2, 700 s (Isp). • What is the cost? – ~$1 B Total SEP Stage Cost ($521. 5 M DDT&E + $435. 1 M Flight Unit) (FY 01 $). • Should the SEP stage remain attached to the Gateway Habitat? – No – better to re-use the stage since its excess power is not needed & its large deployed array area would impact Gateway Habitat field-of-view and work areas. • How many times can/should an SEP stage be reused? – At least 2 roundtrip transfers per SEP stage are feasible by oversizing the solar arrays and assuming LEO replacement of the electric thruster and xenon and A/C system fuels pallets is possible. Ø Should solar array pointing be solar inertial or articulating? – Inertial solar arrays have significant vehicle operations & mass advantages: reduces array area & mass, reduces structural dynamic impacts associated with articulation, allows constant power Hall Thruster operation, thruster boom provides isolation needed to mitigate thruster plume impingement. 11/1/2020 54

Gateway Solar Electric Propulsion (SEP) Stage System Specification Initial conceptual design sizing highlights…subject to further revision! Features ü 180 -day trip time, 400 km 28. 5° LEO to Lunar L 1 15. 0 MT SEP Stage Dry Mass Total, incl. margin 1. 87 Hall Engines & PPUs ü 46 -day return, Lunar L 1 to 400 km 28. 5° LEO 0. 13 Thruster Pallet & Gas Manifold ü 584 k. W SEP Stage Power (supports 2 round trips) 0. 15 PPU Thermal Control 1. 97 Articulated Boom, incl. power, fluid & data lines 1. 21 Xenon Pallet 1. 71 Xenon Tanks 0. 59 SEP Base Structure Mass Characteristics 0. 41 PMAD & Cables ü 15. 0 MT SEP Stage Dry Mass (incl. 20% margin) 0. 30 Attitude Control System 0. 63 Thermal Control System 0. 43 Energy Storage System (Li-ion Batteries) ü 30. 0 MT Payload 2. 93 Solar Array Assemblies ü 65. 0 MT Vehicle Initial Mass LEO 0. 03 Guidance, Navigation & Control 0. 15 Command & Data Handling 2. 50 Margin (20%) ü 7, 300 m 2 High-Voltage Thin-Film Solar Array (2 wings) ü 12 Direct-Drive Hall Effect 50 k. W Engines (incl. 1 spare) ü 20. 0 MT Xenon propellant 11/1/2020 55

Gateway Solar Electric Propulsion (SEP) Stage Issues & Concerns/Forward Work 1. LEO refurbishment Ø Remote/robotics or crew-tended? Ø Thruster pallet replacement Ø Xenon tank pallet replacement Ø ACS propellant replacement/refill 2. Large area array packaging & deployment Ø Dynamic analysis Ø Stiffness requirements 4. Attitude control subsystem refinement Ø Impacts of thruster boom movements Ø Impacts of large deployed area in LEO Ø Momentum wheel & ACS thruster & propellant sizing Ø Rendezvous & docking with payloads 5. Other subsystem sizing/refinement Ø GN&C Ø C&DH 3. Type of thruster boom Ø Deployable (SRTM) vs. rigid (ISS) or combination Ø Stowage & deployment of fluid & power lines Ø Dynamic analysis 11/1/2020 56

Gateway Solar Electric Propulsion (SEP) Stage Thrusters (TRL 3/4): 12 Direct Drive 50 k. W Hall Effect Thrusters (HET) • Xenon, 2500 - 2700 s Isp, 2. 6 N thrust per engine • ~8500 hrs life • 11 HETs required + 1 spare • HET mounted on replaceable 4 m diam. thruster pallet Deployable Thruster Boom (TRL 7): • 35 m articulated boom for thrust vectoring (18. 5 m deployable boom + 8 m inner & outer rigid booms) Replaceable Xenon Tank Pallet (TRL 7) • 4 m diam x 4 m cylinder (3 internal tanks) SEP “Main Body” Rigid Booms (at both ends of deployable boom) Xenon Tank Pallet Deployable Boom Solar Arrays not shown (see below) Radiator (x 4) Thruster Pallet with Hall Effect Engines Gateway Habitat Payload Photovoltaic Arrays (TRL 3/4): Two 3, 750 m 2 AEC-Able Square. Rigger style wings • Thin-film cells (12% AM 0 eff. , 2006 target) Xenon Pallet SEP main body (4. 5 m diam x 1. 5 m) contains: • Array mechanisms • Energy storage (Li-ion) & power processing • Attitude & reaction control systems • GN&C and C&DH systems • Docking interfaces 11/1/2020 SEP Main Body Thruster Boom HET Pallet 57