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ACE Architecture: Mission design studies

ACE Architecture: Mission design studies. ACE Science Workshop March 10 th , 2009 Armin T. Ellis, Deborah Vane, Mark Rokey Jet Propulsion Laboratory. Outline. Context of study Payload and mission parameters Study results Conclusions. Context of Study.

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ACE Architecture: Mission design studies

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  1. ACE Architecture: Mission design studies ACE Science Workshop March 10th, 2009 Armin T. Ellis, Deborah Vane, Mark Rokey Jet Propulsion Laboratory

  2. Outline • Context of study • Payload and mission parameters • Study results • Conclusions

  3. Context of Study • Not ACE, but a study that will provide tradeoff data and lay the ground work for other configurations • Provide a reference for future studies to build on • This study: • Consider only Cloud Profiling Radar (CPR) instrument on platform • Use commercial buses • Gain an understanding of available margins

  4. Upcoming Studies • Consider a commercial bus platform with both the CPR and HSRL (High Spectral Resolution Lidar) • GSFC – MDL: • PACE Platform (Ocean Color + Polarimeter) • Radar + Lidar + Polarimeter

  5. Team-X: Concurrent engineering • Customer presents mission outline • Team-X performs analysis: Mission analysis, Propulsion, Attitude Control, Thermal, Communications, Ground systems, Data Handling, Science, Risk, Cost, etc.

  6. Overview of System Parameters • Launch Date: January 1, 2018 • Launch Vehicle: Atlas V 401 • Mission Life: 1 Month On-Orbit Checkout and 3 Year Science Operations • Consumables sized to allow for 2 year extended mission • Redundancy: Dual (cold) • Stabilization: 3-Axis • Mission Class: B

  7. Payload: Cloud Profiling Radar • Dual frequency (35.6GHz, 94GHz) radar with Doppler capability • High flight heritage from the CloudSat mission • Basic requirements • Power 600W • Data rate 20Mbps (can be compressed and reduced) • Mass 460Kg • Pointing requirements • Accuracy: 72 arc seconds • Knowledge: 40 arc seconds • Stability: 10 arc seconds / seconds • Dimensions • Electronics – 0.3m x 2m x 1.6m • Baseline Antenna – 5m x 2.5m, 1.6m deep (paraboloid)

  8. Study Options • Primary – Consider the CPR payload in two orbits (EarthCARE and GCOM-W), on two different commercial busses • Secondary – Obtain maximum antenna size with two standard launcher fairings

  9. Results

  10. Station Keeping • Maneuvering with other space assets may yield different results, depending on their station keeping strategies

  11. Station Keeping • Orbit Maintenance (Ground Track) at 450 km • 11-40 days between maneuver sets (two maneuvers per set) • Worst-case maneuver magnitude 0.5 m/s per maneuver at end of mission • Launch Cleanup: 15 m/s, Drag-Make up: 96 m/s Total delta-V budget of 111 m/sec • Orbit Maintenance (Ground Track) at 705 km • 40-195 days between maneuver sets • Worst-case maneuver magnitude is 0.14 m/s per maneuver at end of mission • Launch Cleanup: 15 m/s, Drag-Make up: 6 m/s, De-orbit: 38 m/s Total delta-V budget of 59 m/sec Not needed for 450km orbit

  12. Ground Stations – 450km Orbit • Svalbard passes range from 0.9 to 8.6 minutes (mean 7.3 minutes) – Insufficient time to download data given the heritage 343Mb Solid State Recorder size • Trades considered: • Add more ground stations • Lower data acquisition (still under study)

  13. Ground Stations – 450km Orbit • Add Poker Flats and Wallops: • added cost was approx $1.5 M • Reduce data: • Science impact, compression software and hardware development with no heritage Wallops Svalbard Poker Flats Ground Station Access Time Plot

  14. Ground Stations – 705km Orbit • Svalbard has contacts ranging from 4.34 to 11.68 minutes (mean 9.58 minutes) – Sufficient time to download data given the heritage 343Mb Solid State Recorder size Wallops Svalbard Poker Flats Ground Station Access Time Plot

  15. Maximizing Radar Dish Size in Atlas V 401’s 4m Fairing • Antenna width increase from 2.5m x 5m to 3m x 5m • Minimal cost change: • Cost should remain the same since manufacturing is cost is dependent on the maximum dimension of the dish • Tilting the antenna may save some mass in the antenna support structure with smaller struts • Reduced Risk: • No deployment necessary

  16. Larger Antenna Spacecraft 3m 5m Spacecraft in Fairing (Top View) Spacecraft in Fairing (Front View) Spacecraft in Fairing (Iso View) 16

  17. Larger Antenna Spacecraft Spacecraft (Flying View) Spacecraft (Side View) Spacecraft (Front View) 17

  18. Summary of Results Atlas V 401

  19. Conclusions

  20. Conclusions • Station keeping easier at higher orbit • Controlled re-entry is needed higher orbit • Science objectives satisfied in both orbits with the radar antenna size achievable on AtlasV or larger vehicles • Fewer ground stations needed at 705 km • There are advantages to both orbits (EarthCARE and GCOM-W) • 67% mass margin with Atlas 401 launch vehicle – Multiple payloads on the same launch vehicle or more payloads on the same bus

  21. Acknowledgments • Deborah Vane, Mark Rokey, Simone Tanelli, Stephen Durden, Chialin Wu - JPL • Team-X members • Lisa Callahan, Mark Schoeberl – GSFC Questions?

  22. Design Assumptions

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