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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 2  Requirements & Assumptions  Baseline Configuration  Options Considered  Comments, Issues, Concerns Outline

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 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 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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 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 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

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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 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 DSN 5 Mbps  Ranging for collision avoidance

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 8 Baseline Configuration Overview

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 9 Baseline Configuration Overview

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 10 Baseline Configuration Instrument Resources Summary

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

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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 13 Baseline Configuration Mission Mass Summary

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 14 Baseline Configuration Payload Cost [$M]

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 15 Baseline Configuration Hub S/c Subsystems Cost [$M]

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 16 Baseline Configuration Detector S/c Subsystems Cost [$M]

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 17 Baseline Configuration One FF S/c Subsystems Cost [$M]

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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 19 Additional Issues To Consider Smaller 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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 20 Additional Issues To Consider Bigger 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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 23 Tall Poles  Tall Pole 1: Multi s/c formation flying  ACS: Position control to microns over 100’s of m, and to cm’s over 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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 24 Tall Poles  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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 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

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 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 provides launch vehicle performance information and other useful design data.  Rapid Spacecraft Development Office at provides spacecraft bus studies and procurement services.

Final Version MAXIM-PF, May 13-17, 2002 Goddard Space Flight Center System Page 28 System Summary  GSFC Contact: Keith Gendreau  Phone Number: 301/  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: 3000 kg