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

This chapter summarizes some valuable lessons that were learned during the GP-B mission, selected bestpractices employed during this time that helped to make mission operations effective and efficient, and finally,some lessons about the GP-B Management Experiment, summarized from Gravity Probe B: A Management Study, anindependent report presented to NASA by Edward S. Calder and Bradley T. Jones in April 2006.16.1 Lessons LearnedGravity Probe B logged 23 anomalies of various levels of severity and 170 observations during the 17-monthflight mission. Most of these are specific to the Gravity Probe B vehicle and mission, and thus do not havesignificant applicability outside of the project. However, the following lessons have been identified that havebroad applicability across other spaceflight projects. Included in this list are also significant lessons learned fromthe vehicle development and testing period preceding launch that also may be beneficial to other spaceflightprograms.Throughout the development and operation of the satellite, Gravity Probe B has also attempted to adopt “bestpractices” from lessons learned from other programs as well as the combined wisdom and experience of theteam at Stanford, Lockheed-Martin, and NASA Marshall. We would like to affirm a number of practices asespecially effective and worthy of continued adoption by the community.16.1.1 Pre-launch lessons learnedThe following subsections summarize lessons learned prior to launch of the GP-B spacecraft on April 20, 2004.16.1.1.1 Power system monitoringIssue Summary: Extensive, detailed power system monitoring is beneficial.Description of the GP-B experience:Both during pre-launch testing and on orbit, it has been useful to carefully monitor the performance of thepower system throughout the space vehicle. Many of the spacecraft and payload subsystems provide some levelof power system monitoring, however, in some important instances, no explicit pre and post regulation powermonitoring was provided. The engineering team, thus, had to rely on some of ancillary monitors to infer theperformance of some box power systems.Lesson:• Include voltage and current monitoring for the primary and secondary sides of all power conversionsystems as a standard design requirement for all custom designed power supplies.16.1.1.2 Early engineer involvementIssue Summary: Involve subsystem engineers early in display page development.Description of the GP-B experience:Formatting and design of operations console display pages (numeric data displays and graphs) were many timesput together without RE input. There wasn’t enough time spent to ensure presentation of data was sufficient.Lessons:1. Involve the users early enough to allow them to have input into the monitors that they will need to use.Many displays pages have monitors that were useful for testing, but not for operations.2. The display page should allow the user to easily modify the display.Gravity Probe B — Post Flight Analysis • Final Report March 2007 443