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X-Ray Gratings Mission

X-Ray Gratings Mission. Mission Systems Rud Moe Theo Bugtong Frank Kirchman 19 – 23 March, 2012. X-Ray Grating Mission Requirements (from customer). X-Ray Grating Mission Requirements, cont’d. X-Ray Grating System Design Overview. Mechanical

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X-Ray Gratings Mission

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  1. X-Ray Gratings Mission Mission Systems Rud Moe Theo Bugtong Frank Kirchman 19 – 23 March, 2012

  2. X-Ray Grating Mission Requirements (from customer)

  3. X-Ray Grating Mission Requirements, cont’d.

  4. X-Ray Grating System Design Overview • Mechanical • 8 Sided Gr-Ep S/C structure surrounding primary mirror • Lower deployable SA to match CP to CG and provide sunshade • Thermal • Sunshades to accommodate +25, -45 Pitch angle • Cold bias baseline with heater control • Propulsion • Mono prop system for orbit maintenance and momentum unloading, 12 thrusters • Attitude Control • Star trackers (2 heads, redundant processor), SIRU (internally redundant), sun sensors (8) for determination • Momentum wheels (4) for control • Communications • Two DSN S/Ka-band transponders • Two 10 watt Ka-band TWTAs • Gimbaled 0.5 M dual frequency high-gain antenna • DSN 34m antenna • Power • 6.7 m2 SA • 28V bus • 100 AH battery

  5. X-Ray Grating System Design Overview, cont’d. • Avionics • Build to print system • Primary C&DH System with Cold Backup system • SW • High heritage reuse • No challenging requirements for Xray Grating • I&T • GSFC facilities baselined • MSFC XRCF consideration for optical verification • Ops • COTS/GOTS MOC baselined • Reliability • Class B • Launch Vehicle • Falcon 9 • Orbital Debris • No specific disposal method required • Flight Dynamics • Standard L-2 halo or Lissajous

  6. X-Ray Grating Mass

  7. X-ray Grating Mission Timeline

  8. X-Ray Grating Ops Concept

  9. X-Ray Grating Observatory Concept

  10. X-Ray Grating S/C Block Diagram

  11. X-Ray Grating Power

  12. X-Ray Grating CommunicationsFunctional Configuration decrypter S S/Ka-band Transponder Diplexer Hybrid S S-Band omnis PA SWITCH K S decrypter S C&DH Diplexer PA S SWITCH S/Ka-band Transponder S Hybrid SWITCH ISOLATOR Ka-band TWTA SWITCH S / Ka HGA Triplexer K Ka-band TWTA

  13. X-Ray Grating Program flow Mission Critical Design Review (CDR) 9/28/2018 Phase B Start S/C Bus 8/8/2016 Preliminary Design Review (PDR) 9/1/2017 S/C Bus Contract Award System Definition Review (SDR) Project Start 8/8/2014? Phase A Preliminary Analysis Phase B Definition and Prelim Design Phase C Final Design Preliminary Design Mission Definition System Definition Final Design 11 months 24 months 13months Transition To Nominal Ops 7/11/2021 End of Primary Mission 3/15/2024 Instrument Delivery 2/1/2019 4/10/2020 5/8/2020 Launch 6/11/2021 Ship 2/26/2021 Funded Reserve Phase D-1 Subsystem Development, S/C Integration & Test, Launch Prep Phase E/F Operations Phase D-2 Launch & Checkout Funded Reserve Fab., S/C Assy & Func. I&T ~16mo.s Prep for Launch ~3mos Obser. I&T 9.5mo.s Cruise, Orbit Insertion & Checkout PrimaryMission Reserve 7 mo.s Launch & Checkout Extended Mission ? 29months 7months 1 month 2mo 33 mo Timeline not to scale

  14. X-Ray Grating – Systems Implications for CAT configuration • CAT instrument potential system-wide impacts and implications • Instrument Mass reduced to 84.5 kg • Structure mass • Fuel mass • Thrusters size • Inertia • Attitude Control torquers size • CG • CP-CG shield position • Thrusters alignment • Instrument Power reduced to 85 W (affects power and thermal) • Solar Array size • Battery DOD or size • Thermal load • Radiator sizes • Avionics TT&C and FSW specifics • System interaction impacts not fully assessed

  15. X-Ray Grating Issues/Considerations • Tracking required for 1 msec absolute timing • Reaction wheels sized for 1-month momentum management cycle • 21-day nonpropulsive tracking arc may possibly be shortened • Portion of timing error allocated to position uncertainty is TBD • Pitch pointing produces CP-CG offset and solar pressure momentum accumulation, and may require more frequent momentum management • Momentum management with coupled thrusters produces a small contribution to position delta-V • Position uncertainty also influences station-keeping delta-V • Arrangement of target pointing sequence may help balancesolar pressure momentum accumulation • Aperture cover mechanism versus safehold solar pointing reliability • Aperture cover is jettisoned; recloseable cover is not baselined • Increased reliability of safehold solar pointing may be more cost effective and reliable than a recloseable cover

  16. X-Ray Grating Future Work • Weight-optimized configuration • Reconfigured Payload configurations • Extensive redesign needed to reach smaller LV accommodations • Attitude determination analysis • Error budgets

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