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Gabe Karpati May 17, 2002

Micro-Arcsecond X-ray Imaging Mission, Pathfinder (MAXIM-PF). System Overview. Gabe Karpati May 17, 2002. Outline. Requirements & Assumptions Baseline Configuration Options Considered Comments, Issues, Concerns. Requirements & Assumptions Study Overview. Mission objective

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Gabe Karpati May 17, 2002

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  1. Micro-Arcsecond X-ray Imaging Mission, Pathfinder (MAXIM-PF) System Overview Gabe Karpati May 17, 2002

  2. Outline • Requirements & Assumptions • Baseline Configuration • Options Considered • Comments, Issues, Concerns MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  3. Requirements & Assumptions Study Overview • Mission objective • X-ray interferometry mission, a pathfinder to full MAXIM • Original requirements • As formulated in the Prework and in K. Gendreau’s “going-in-13may02.ppt” • Original requirements modified during the study • Lifetime for Phase 1: 1 yr required / 50 targets (1wk/target); • Lifetime for Phase 2: 3 yrs required / 4 yrs goal (3 wks/target) • Additional constraints, challenges • 2015 launch • Primary purpose of this study • Identify mission drivers and breakpoints • Identify technologies required • Subsystem configuration, mass and cost estimates • Length of study • 5 days MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  4. Requirements & Assumptions Major Driving Requirement Areas • High precision pointing • Centroid image of a laser beacon for microarcsec LOS alignment • Point by referencing microarcsec image of stars or use GPB-like microarcsec grade Super-Gyro • Multi s/c formation flying • Orbital dynamics: Formation acquisition and control; Orbits; Transfer to L2 • Propulsion: Thrust needs to vary by several orders of magnitude • ACS: Position control to microns over 100’s of m, and to cm’s over 20000 km, knowledge to microns; Retargeting issues • Software • To accommodate all functions • Verification • Functional and performance verification 1 g environment • Thermal control • Handle two thermally very dissimilar mission Phases with one h/w • Control to .1 degree to maintain optical figure • “STOP” CTE effects • Communication • Complex communications web: Detector to Ground; Hub to Detector; Hub to FFs; FF to FF; Rough ranging using RF MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  5. Baseline Configuration Experiment Overview • Observatory configuration • One Hub spacecraft, one Detector spacecraft, six Free Flyer spacecraft • Hub communicates with Detector and the Free Flyers • Detector communicates with ground • Phase 1: 100 microarcsec Science • 2 formation flying objects at 200 km • Phase 2: 1 microarcsec Science • Hub surrounded by 6 identical Free Flyers in a circle of 200-500 m, Detector at 20,000 km • Distance from Hub to Detector: RF ranging course & time of flight for fine ranging and control (~5m) • Align Hub and Detector using Superstartracker that centroids the image at the Detector of a LISA - like laser beacon mounted on Hub (microarcsec) • LOS pointing: reference beacon image to image of stars in background w/ Superstartracker or use GPB - like Super-Gyro (microarcsec) • HUB to FF’s distance: w/ RF ranging course; Laser interferometer fine w/ corner cubes on Hub (~10 um); • FF position: use FF startrackers (~arcsecs)looking at LED on Hub MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  6. Baseline Configuration Experiment Overview Diagram courtesy of K. Gendreau Optics Hub S/C • Pitch, Yaw, control to ~ 1 arcsec, roll control to arcmins • Pitch, Yaw, Roll Knowledge to +/- 1 arcsecond • LOS to target knowledge to ~0.1 milliarcsec (~15 microns @ 20,000 km) • FreeFlyer S/C • Pitch, Yaw control to ~1 arcsec • Pitch, Yaw Knowledge to arcsecs • Roll Control to 30 milliarcsecs MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  7. Baseline Configuration Experiment Overview • Continuous full sun • Battery required for safe Phase only • Transfer to L2 • Takes up to 6 months • All S/C are attached together • High thrust chemical propulsion • Transfer stage is jettisoned at L2 • Communication web • HUB to Free Flyers • HUB to Detector • All Space-Ground communications performed by Detector spacecraft • IP, 50 Kbps; One contact day @ DSN 5 Mbps • Ranging for collision avoidance MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  8. Baseline Configuration Overview MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  9. Baseline Configuration Overview MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  10. Baseline Configuration Instrument Resources Summary MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  11. Baseline Configuration Metrology System Resources Summary MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  12. Baseline Configuration S/c Mass Summaries MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  13. Baseline Configuration Mission Mass Summary MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  14. Baseline ConfigurationPayload Cost [$M] MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  15. Baseline ConfigurationHub S/c Subsystems Cost [$M] MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  16. Baseline ConfigurationDetector S/c Subsystems Cost [$M] MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  17. Baseline ConfigurationOne FF S/c Subsystems Cost [$M] MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  18. Baseline Configuration Overall Cost Summary [$M] MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  19. Additional Issues To ConsiderSmaller RSDO Busses • RSDO On-Ramp II in force • RSDO On-Ramp IV selection in process • Several new buses added, to increase choice • Spectrum Astro SA 200B, Bus dry mass = 90 kg • Payload Power (OAV) (EOL) / Mass Limit: 86 W / 100 kg • Orbital - Microstar, Bus dry mass = 59 kg • Payload Power (OAV) (EOL) / Mass Limit: 50 W / 68 kg • Ball BCP 600, Bus dry mass = 203 kg • Payload Power (OAV) (EOL) / Mass Limit: 125 W / 90 kg • Orbital - Leostar, Bus dry mass = 263 kg • Payload Power (OAV) (EOL) / Mass Limit: 110 W / 101 kg • Surrey - Minisat 400, Bus dry mass = 207 kg • Payload Power (OAV) (EOL) / Mass Limit: 100 W / 200 kg • TRW - T200A, Bus dry mass = 242 kg • Payload Power (OAV) (EOL) / Mass Limit: 94 W / 75 kg SA 200B BCP 600 MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  20. Additional Issues To ConsiderBigger RSDO Busses • Swales EO-SP (new in RSDO II catalog) • Bus dry mass = 370 kg • Payload Power (OAV) (EOL) / Mass : 80 W / 110kg • Spectrum Astro SA 200HP • Bus dry mass = 354 kg • Payload Power (OAV) (EOL) / Mass Limit: 650 W / 666 kg • Lockheed Martin - LM 900 • Bus dry mass = 492 kg • Payload Power (OAV) (EOL) / Mass Limit: 344 W / 470 kg • Orbital StarBus • Bus dry mass = 566 kg • Payload Power (OAV) (EOL) / Mass Limit: 550 W / 200 kg • Orbital – Midstar • Bus dry mass = 580 kg • Payload Power (OAV) (EOL) / Mass Limit: 327 W / 780 kg • Ball BCP 2000 • Bus dry mass = 608 kg • Payload Power (OAV) (EOL) / Mass Limit: 730 W / 380 kg EO-1 Midstar SA200HP -DS1 MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  21. Comments, Issues and Concerns I&T, Requirements Verification • Environmental verification • Standard, per GEVS • Any end-to-end testing / verification of the critical subsystems is very difficult or near-impossible in a 1 g environment • E-E verification of orbit maintenance and formation flying capabilities near-impossible • E-E verification of metrology system near-impossible • E-E verification of X-ray beam focus and alignment is difficult • Reasonable trades must be made on verification approaches, goals, and requirements • That alone is a very significant body of work MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  22. Maturity,Technologies, TRL • MAXIM is feasible ! • MAXIM does not factor in any unrealistic technology expectations or technologies un-envisionable today • Fairly mature and serious plans, even for the metrology • Still, a staggering amount of technology development is required: • Metrology system: H/w and s/w elements • Superstartracker • GPB - like Super-Gyro for pointing • Software • Formation flying and “virtual-one-body” telescope control software • Analysis and simulation techniques • Propulsion system • Very low thrust technologies, extremely variable force thrusters • Verification approaches and technologies for FF LAI missions • Simulators • Low CTE optical/structural materials • General TRL Level of MAXIM key technologies today is 2-3 MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  23. TallPoles • Tall Pole 1: Multi s/c formation flying • ACS: Position control to microns over 100’s of m, and to cm’s over 20000 km, knowledge to microns; Retargeting issues • Orbital dynamics: Formation acquisition and control; Orbits; Transfer to L2 • Metrology System: swarm sensors, interferometric range sensors, beacon detecting attitude sensors • Tall Pole 2: High precision pointing • Centroid image of a laser beacon for microarcsec LOS alignment • Point by referencing microarcsec image of stars or use GPB-like microarcsec grade Super-Gyro • Tall Pole 3: Software • To accommodate all required functions • Tall Pole 4: Propulsion • Continuous smooth micro-thrusters • Thrusters force variable by orders of magnitude MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  24. TallPoles • Tall Pole 5: Verification science • Theoretical “risk-science” assessment on feasible verification vs. available resources • Functional and performance verification in 1 g environment • “STOP” CTE effects • Tall Pole 6: Thermal control • Control to .1 degree to maintain optical figure • Handle two thermally very dissimilar mission phases with one h/w • Tall Pole 7: Communication • Complex communications web: Detector to Ground; Hub to Detector; Hub to FFs; FF to FF; Rough ranging using RF • Tall Pole 8: Mirror element actuators & software • General TRL Level of key technologies today is 2-3 MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  25. Additional Issues To Consider • Startracker on FF opposite the Hub – Sun line would stare at Sun • Since 6 FF’s are 60 degrees apart, roll entire formation, to have two FFs closest to Hub – Sun line at equal 30 degrees • This concept doesn’t work for a higher number of FF’s, unless FF startracker FOV is sufficiently narrowed (complicates access to star-field) • Structural-Optical-Thermal effects • Not fully addressed yet • Thermal control to 1.5 mK required – not trivial ! • Lower CTE optical/structural materials? • Structural stability between the attitude sensor and the instrument • It is good practice to mount the attitude sensors and the instrument on a common temperature controlled optical table • Free Flyers station fixed • Free Flyer station clocking position in circle around Hub is constrained • To change position, while keeping mirrors in alignment requires rolling the FF s/c • Rolling of FF s/c is disallowed for sun / anti-sun sides must be pointed right • Mounting FF Mirror Assemblies on turntable would allow repositioning of any FF s/c to any station MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  26. Additional Issues To Consider • Other mission orbits should be fully explored • Earth leading/trailing drift away orbit at .1 AU/year • Distant retrograde orbits • Solar-libration: “kite-like” solar sail “floating” on a toroid-like pseudo-libration surface which envelops L1 between Sun-Earth • Calibration Plan • Calibration may be a major requirements driver, must be factored in early on • Communications network architecture • Communications between constellation elements: much refinement is required • TDRSS at L2? Servicing at L2? • Explore synergies and joint funding possibilities w/ other LAI missions at L2 • Servicability at L2 • Design shouldn’t of the bat preclude future serviceability • Coordinate w/ servicing planners MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  27. Supporting Data • Systems spreadsheet tool: “LAI-MAXIM-PF_System_Sheets.xls” • System configuration summaries • Mass and cost rollups and detailed ISIS subsystem data • Quick propulsion calculator • Prework information • WBS template: “Generic_WBS_Template_by_GSFC_NOO.doc” • Full NASA mission’s complete Work Breakdown Structure • Compiled by GSFC New Opportunities Office • Useful web sites • Access to Space at http://accesstospace.gsfc.nasa.gov/ provides launch vehicle performance information and other useful design data. • Rapid Spacecraft Development Office at http://rsdo.gsfc.nasa.gov/ provides spacecraft bus studies and procurement services. MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

  28. System Summary • GSFC Contact: Keith Gendreau • Phone Number: 301/286-6188 • Mission name and Acronym: MAXIM-Pathfinder • Authority to Proceed (ATP) Date: Dec 2007 • Mission Launch Date: 2015 • Transit Cruise Time (months): n/a • Mission Design Life (months): 48 • Length of Spacecraft Phase C/D (months):72 • Bus Technology Readiness Level (overall): 3 • S/C Bus management build: TBD • Experiment Mass: 3000kg MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

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