ACE Science Workshop March 10 th, 2009 Armin T. Ellis, Deborah Vane, Mark Rokey Jet Propulsion Laboratory

 Context of study  Payload and mission parameters  Study results  Conclusions

 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

 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 CPR + HSRL HSRL Orbit 450 km Sun Sync 705 km Sun Sync 450 km Sun Sync 705 km Sun Sync Spacecraft Bus Spectrum Astro Ball Aerospace

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

 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

 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)

 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 Option 1Option 2Option 3Option 4 Spacecraft Bus Ball BCP 2000 Orbital LEO Star II Orbit 450 km Sun Sync 705 km Sun Sync 405 km Sun Sync 705 km Sun Sync

 Maneuvering with other space assets may yield different results, depending on their station keeping strategies

 Orbit Maintenance (Ground Track) at 450 km ◦ 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 ◦ 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

 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)

 Add Poker Flats and Wallops: ◦ added cost was approx $1.5 M  Reduce data: ◦ Science impact, compression software and hardware development with no heritage Svalbard Wallops Poker Flats Ground Station Access Time Plot

 Svalbard has contacts ranging from 4.34 to 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

 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

February 11th & 12th, Spacecraft in Fairing (Front View) Spacecraft in Fairing (Top View) 3m Spacecraft in Fairing (Iso View) 5m

February 11th & 12th, Spacecraft (Side View) Spacecraft (Front View) Spacecraft (Flying View)

S/C Wet Mass LV Mass Margin Data Storage Ground Stations Controlled De-orbit Cost 450km 2200 kg 68%343 Gbit3117 m/s$592.7M 705km 2175 kg 67%343 Gbit1184 m/s$584.1M Atlas V 401

 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

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

22February 11th & 12th, 2008