GP-B Post-Flight Analysis—Final Report - Gravity Probe B - Stanford ...

Figure 5-4. Metric of risk item closure prior to launch of GP-B. All risk items were either acceptedor closed prior to launch.During the on-orbit phase of the mission, we continued the risk management approach on GP-B. Table 5-1provides a summary of the open risk items at the end of the IOC phase. Figure 5-5, Figure 5-6, and Figure 5-7provide the open risk items at the end of the science mission phase.Risk management was successfully implemented on GP-B and provided a disciplined process to identifying andmanaging program risk.Table 5-1. Summary of Open GP-B risks at the end of IOCRisk # Subject Owner Mitigation5 B side switch impact to attitudeand recovery to star. SV rollsdown to 0.1 rpm on b-sideswitch.22 Maintain ATC attitude control forscience25 Loss of suspension due tountested post spin upoperations29 Roll Frequency Accelerations atRotor. SI at roll. Variation is sumof the squares of voltages onone electrode axis.BarryKirschenbaumFD,MD,ARBKeiserDraft B-side safemode recovery procedurecompleted. Walk-through scheduled for 9/14/04.Close risk when procedure and training arecompleted. On-call team available for recovery.Reassess the limits for DBE test activation. Plan B-sidetable top rehearsal and additional FD & MD trainingfor initial actions to stop roll down.Recent improvements made in pointingperformance. Roll phase variation improvementexpected by star tracker alignment implemented on9/10/04. Monitor ATC attitude performance. RTWorksupgrade in work for loss of star identification. Watch.Continuous mitigation - Increased vigilance onPPCR's and changes. Maintain constant MOCdiscipline. Minimize GSS commanding.Open – Watch – continue to monitor. Preliminarylook by Alex advises we are OK.Gravity Probe B — Post Flight Analysis • Final Report March 2007 135