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Micro-Arcsecond X-ray Imaging Mission Pathfinder (MAXIM-PF) System Overview

This document provides an overview of the MAXIM-PF mission, including the requirements, assumptions, baseline configuration, options considered, and comments and concerns. It covers major driving requirement areas, the baseline configuration experiment overview, and summaries of instrument resources, metrology system resources, s/c mass, mission mass, and payload cost.

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Micro-Arcsecond X-ray Imaging Mission Pathfinder (MAXIM-PF) System Overview

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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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