AEROSPACE REPORT NUMBER: ATR-2009-9369-1, CRITICAL CLEARANCES IN SPACE VEHICLES (31-OCT-2008)

AEROSPACE REPORT NUMBER: ATR-2009-9369-1, CRITICAL CLEARANCES IN SPACE VEHICLES (31-OCT-2008)., Subject matter experts from various National Security Space companies reviewed 164 ground and 24 onorbit anomalous deployment incidents and their root causes. Table 1 summarizes this study by showing the number of anomalies associated with various root cause �categories� shown. For the interested reader, Appendix A describes all the root cause �categories.� There was some overlap between on-orbit causes, i.e., some anomalies had more than one cause, which is why the total is less than the sum of the individual categories. The table clearly shows that insufficient critical clearances caused the most ground test anomalies, and contributed on par with other causes to on-orbit anomalies. The purpose of this paper, under the auspices of the SQIC, is to assist in further focusing attention on critical clearances processes, with the goal of reducing the number of critical clearance related anomalies in the future.