Contingencies Manfred Bester THEMIS FDMO CDR Peer Review

Contingencies Manfred Bester THEMIS FDMO CDR Peer Review − Contingencies 1 June 1 -2, 2004

Contingencies Overview • • Flight System Contingencies Ground System Contingencies Contingency Operations Contingency Recovery THEMIS FDMO CDR Peer Review − Contingencies 2 June 1 -2, 2004

Flight System Contingencies Contingency Situations with Flight Systems • • • Flight Software or Command Load Problems On-board Computer Resets Malfunction of Critical Probe Systems Malfunction of Sensors or Instruments Temperature Induced Malfunction or Damage High-voltage Arcing Single Event Phenomena (SEU, SEL, SEB) Permanent Radiation Damage to Electronics Malfunction of Mechanical Systems Meteorite Hits or Solar Events On-orbit Collisions with Other Spacecraft or Debris Operator Errors THEMIS FDMO CDR Peer Review − Contingencies 3 June 1 -2, 2004

Ground System Contingencies Contingency Situations with Ground Systems • • Natural Disasters Intentional or Accidental Damage Extended Power Outages Loss of Network Connectivity Loss of Data Hardware Failures Unavailability of Critical Personnel THEMIS FDMO CDR Peer Review − Contingencies 4 June 1 -2, 2004

Contingency Operations • • • Assessment of Plausible Failure Modes Performed During Mission Design Phase Results Taken into Account in Probe Design Fault Tree Software Tool Will Allow FOT to Perform Quick Database Search Consultation with Bus and Instrument Engineering Support Team and Project Management for Contingency Recovery Corrective Actions Carefully Planned and Subsequently Executed Safe Mode • • Probes Passively Spin Stabilized Normal to the Ecliptic Plane Power Positive in 4π sr Fault Tolerant Design with Graceful Degradation Communications to Farthest Apogee at Low Data Rates CMD: 1. 0 kbps, TLM: 1. 024 or 4. 096 kbps THEMIS FDMO CDR Peer Review − Contingencies 5 June 1 -2, 2004

Contingency Recovery Contingencies During L&EO • • • Separation from PCA Probe Turn-on Attitude Maneuvers Phasing Errors of ACS Sensors Orbit Maneuvers RCS Anomalies Instrument Commissioning Ground Station Failure Ground Network Failure Constellation Related Contingencies Contingency Plan Under Development • • Swales, Hammers and UCB EO-1 Model Adopted for Layout of Contingency Tree THEMIS FDMO CDR Peer Review − Contingencies 6 June 1 -2, 2004