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

effects appear greater than ground testing would indicate. Though all of these subjects were studiedextensively before launch, our best knowledge about how the instrument operated was not as accurate asanticipated. Only on-orbit operation made it possible to identify and mitigate these issues.4. Invest in high fidelity simulations. Hardware in the loop simulators are critical to validate the overalleffectiveness of a complicated scientific instrument and satellite system. Where the instrument cannot beoperated on the ground, suitable high fidelity simulations with flight compatible interfaces must bedeveloped. These simulators, however, must be vetted against flight data and updated once actualperformance data are known. This is required to be able to resolve operational anomalies16.1.3 IOC Observations by Lewis Wooten of NASA MSFCThe GPB Operations team has done an exceptional job conducting the Launch and the IOC phases of themission. The team is very intelligent, extremely dedicated, and has an unprecedented commitment to missionsuccess. Plus, they are just a wonderful group of individuals to work with. I measure an operations teamperformance on its ability to learn from mistakes, and adapt quickly to change, and make the right subsequentdecisions. On this basis, the GP-B team is one of the best in the business, and it is a team that will continue tomake adjustments and improve along the way. With that being said, I have very little to offer in terms ofsuggestions for improvements at this phase of the mission. However, if I am pressed to come up withsomething, I have provided the following two observations for consideration.16.1.3.1 Execution of Pass Plan Change RequestIssue Summary: The PPCR screening, approval, and execution process work extremely well for the majority ofthe cases, however it was not always consistentDescription of the GP-B experience:Given the dynamic approach used in troubleshooting some of the ATC sub-system problems, many of theirPass Plan Change Requests (PPCR’s) was executed without a through review with the flight team. There weretimes when they were pressed to send the commands before a specific communication pass expired, withoutbeing given the opportunity to participate in the screening process. The flight team are not “just buttonpushers”, they should be aware of what, why, when, the expected results, and fallback plans before they given “aclear to execute.” I did see this as a significant problem and it should not be an issue during the science missionphase.Lesson:Take the time necessary to get the flight team completely onboard before they are asked to execute a PPCR.Stanford modified the PPCR process to address this issue, which improved the process for a group that had alarge number of issues. It allowed them to work the problems yet it maintained discipline while not becomingadministratively difficult.Gravity Probe B — Post Flight Analysis • Final Report March 2007 453