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

Anomalies are classified into 4 categories:1. Major Space Vehicle Anomalies—Major Space Vehicle Anomalies endanger the safety of the spacecraftand/or the payload. These anomalies generally have contingency plans that have been pre-approved forimmediate identification and response within the MOC at the direction of the Flight Director. Responseto these anomalies is time-critical.2. Medium Space Vehicle Anomalies—Medium Space Vehicle Anomalies do not endanger the safety ofthe space vehicle but may impact the execution of planned timeline. These are the most probable type ofanomaly because the vehicle safing mechanisms are designed to allow the vehicle to be autonomous for72 hours given any single failure. The response to these anomalies is not time-critical if addressed withinthe 72 hour window.3. Minor Space Vehicle Anomalies—A Minor Space Vehicle anomaly does not endanger the safety of thespace vehicle and does not stop the execution of the timeline. These anomalies also do not have any longtermimplications to on-orbit operations. This category covers extremely low risk problems with thevehicle that are typically completely corrected by taking the appropriate corrective action.4. Space Vehicle Observations—In addition to formal anomaly categories, the space vehicle may exhibitoff-nominal or unexpected behavior that does not appear initially to be an operational or functionalissue and does not violate any limits, but may warrant attention over time. Any team member whonotices such issues contacts the anomaly room with the report. These items are designated an“observation” and will be reported daily to the Mission Director and the program on a daily basis, andare resolved on a time-available basis. Observation items may be elevated to an anomaly category if it isjudged to be serious enough to warrant a high-priority investigation.5.3.2 Anomaly Review OrganizationThe anomaly review process is organized into three different entities: the Anomaly Resolution Coordinator, theAnomaly Review Board, and a number of Anomaly teams and Engineering Analysis teams. The roles of theseentities are outlined in Figure 5-1 below.Gravity Probe B — Post Flight Analysis • Final Report March 2007 127