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Gabe Karpati May 17, 2002

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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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outline
Outline
  • Requirements & Assumptions
  • Baseline Configuration
  • Options Considered
  • Comments, Issues, Concerns

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

requirements assumptions study overview
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

requirements assumptions major driving requirement areas
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

baseline configuration experiment overview
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

baseline configuration experiment overview1
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

baseline configuration experiment overview2
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

baseline configuration overview
Baseline Configuration Overview

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

baseline configuration overview1
Baseline Configuration Overview

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

baseline configuration instrument resources summary
Baseline Configuration Instrument Resources Summary

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

baseline configuration metrology system resources summary
Baseline Configuration Metrology System Resources Summary

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

baseline configuration s c mass summaries
Baseline Configuration S/c Mass Summaries

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

baseline configuration mission mass summary
Baseline Configuration Mission Mass Summary

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

baseline configuration payload cost m
Baseline ConfigurationPayload Cost [$M]

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

baseline configuration hub s c subsystems cost m
Baseline ConfigurationHub S/c Subsystems Cost [$M]

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

baseline configuration detector s c subsystems cost m
Baseline ConfigurationDetector S/c Subsystems Cost [$M]

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

baseline configuration one ff s c subsystems cost m
Baseline ConfigurationOne FF S/c Subsystems Cost [$M]

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

baseline configuration overall cost summary m
Baseline Configuration Overall Cost Summary [$M]

MAXIM-PF, May 13-17, 2002Goddard Space Flight Center

additional issues to consider smaller rsdo busses
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

additional issues to consider bigger rsdo busses
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

comments issues and concerns i t requirements verification
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

maturity technologies trl
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

tall poles
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

tall poles1
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

additional issues to consider
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

additional issues to consider1
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

supporting data
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

slide28

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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