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THEMIS Constellation Operations Dr. Manfred Bester University of California at Berkeley

THEMIS Constellation Operations Dr. Manfred Bester University of California at Berkeley. Mission Profile Launch & Early Orbit Campaign Instrument Deployment & Commissioning Coast Phase Mission Orbit Placement Tail Season Science Operations Constellation Status Summary. Mission Profile.

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THEMIS Constellation Operations Dr. Manfred Bester University of California at Berkeley

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  1. THEMIS Constellation Operations • Dr. Manfred Bester • University of California at Berkeley • Mission Profile • Launch & Early Orbit Campaign • Instrument Deployment & Commissioning • Coast Phase • Mission Orbit Placement • Tail Season Science Operations • Constellation Status Summary

  2. Mission Profile

  3. Launch Campaign at KSC • Delta II 7925-10 • 5 Probes in Fairing

  4. Launch & Orbit Insertion • Launch: • Feb. 17, 2007 • Probe Release: L + 70 min • Responsibility for Constellation Operations Transitioned to U.C. Berkeley

  5. THEMIS Mission Data Flows THEMIS Probe TDRS Berkeley Ground Station Wallops Ground Station KSC & Astrotech Merritt Island Ground Station (1) (3) Compatibility Test Van JPL I&T Facility UCB I&T Facility (3) White Sands Complex (3) Secure Intranet Santiago Ground Station Secure VPN Tunnel via Open Internet (2) GSFC NMC Open IONet Dial-up ISDN Line Berkeley Mission Operations Center Notes: Open (1), Restricted (2) or Closed (3) IONet Hartebeesthoek Ground Station Different Routes for End-to-end Data Flows Between Probes and GS Elements

  6. Probe Placement Decision • Probe Placement Decision • Followed Initial Probe Bus and Instrument Check-out and Commissioning Operations on LD + 38 Days • Assigned Constellation IDs (P1−P5) to Probe Buses (A−E) THEMIS B −> P1 4 − Day Orbit THEMIS C −> P2 2 − Day Orbit THEMIS D −> P3 1 − Day Orbit THEMIS E −> P4 1 − Day Orbit THEMIS A −> P5 4/5 − Day Orbit • Decision Based on Probe Bus and Instrument Performance • Only Differences Noted Were in Telecom System – Strongest Performers (THEMIS B & C) Chosen for Largest Orbits • Coast Phase Orbit Set-up • Followed Probe Placement Decision • Maneuver Operations for THEMIS A−E to Rearrange Constellation into String-of-Pearls Configuration in 32-Hour Orbit • Interleaved with EFI Deployment Operations on THEMIS C−E

  7. Coast Phase Orbit Placement Intermediate Orbits Towards Coast Phase Alignment

  8. EFI Deployment • EFI Spin-plane and Axial Boom Deployment • THEMIS C (P2) Was Trailblazer • 13 Deployment Steps Plus Initial Spin-up to 20 rpm • Fortunately No Restrictions on Transmitter-on Times • Four Sets of Alternating Operations • Wire Boom Reel-out on X and Y Axes in 5-m Steps • Spin-up Maneuvers • Sensor Diagnostic Tests • Last Step Was Release of +Z and −Z Axial Booms • All Completed in 7 Working Days • THEMIS D (P3) & E (P4) Followed 3 Weeks Later • Performed Interleaved with Back-to-back Operations • Optimized On-console Staffing • Instrument and Mechanical Engineers for Boom Deploy Operations • Propulsion and Flight Dynamics Teams for Spin-up Operations • All Completed in 5 Working Days • THEMIS B (P1) & A (P5) Deployed After Mission Orbit Placement

  9. Coast Phase Operations • Coast Phase Operations • Purpose of Coast Phase • Additional Mission Phase Inserted to Control Orbital Dispersions Prior to Mission Orbit Placement • Dayside Science Campaign in July and August 2007 • String-of-Pearls Orbit Configuration in 32-Hour Orbit • Instrument Characterization and Tuning • SST Attenuator Operations • EFI Bias Currents, Usher and Guard Voltages, Sensor Diagnostic Tests (SDTs) • Science Data Acquisition • Tuning of Science Trigger Algorithms • Usage of Predicted Magnetospheric Regions of Interest • Optimization of Acquisition and Recovery of Science Data Volumes

  10. Mission Orbit Placement • Mission Orbit Placement • Very Complex Maneuver Operations Schedule • Frequent Rescheduling Required Due to Small Differences Between Predicted and Achieved Maneuver Performance • Also Needed to Work Around Tank Pressure Profile • Total Number of Thrust Operations • Including Entire Orbit Placement and All EFI Deployments: 170 4-Probe Conjunction on Wedding Day (Feb. 2, 2008)

  11. Data Acquisition & Recovery • Science Data Acquisition • Science Data Acquisition Controlled via Predicted Crossings of Magnetospheric Regions of Interest and On-board Triggers • Slow Survey (SS), • Fast Survey (FS) • Particle Burst (PB) • Wave Burst (WB) • Science Data Recovery • Ground Station Passes • Primary Ground Station at U.C. Berkeley • Secondary Ground Station Support via NASA Ground Network and Universal Space Network • Tracking Schedule • One Pass per Perigee at High Data Rate for Data Recovery • Additional Tracking Passes Scheduled for Orbit Maintenance • Transition to Fully Automated, Lights-out Operations Almost Completed

  12. Constellation Status Summary • Constellation Status Summary • THEMIS Mission Completed Almost One Year on Orbit • Currently in Primary Magnetospheric Tail Observing Season • All Five Probes Are Completely Deployed and Very Healthy • All Probe Bus Subsystems Performance Is Nominal • All Instruments Are Powered On and Function Nominally • All EFI Spin-plane and Axial Booms Are Deployed • All Five Probes Are in Their Primary Mission Orbits • Synchronized Orbits with Periods of 4, 2, 1, 1 and 4/5 Days • Attitudes Are Ecliptic North (3) and South (2) • Mission Operations Status • Ground Systems Are Functioning Well • Flight Dynamics Operations Are Almost Routine • THEMIS Web Site at UCB Contains More Information http://themis.ssl.berkeley.edu

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