ANSI/AIAA guide for estimating spacecraft systems contingencies applied to the NASA GLAST mission

An assessment is conducted of the mass and power contingency trends experienced by NASA's gamma ray large area telescope (GLAST) mission from the bid to CDR program design stages with respect to the ANSI/AIAA guide for estimating and budgeting weight and power contingencies for spacecraft systems G-020-1992. The GLAST spacecraft is a gamma ray telescope observatory that is scheduled to be launched into low Earth orbit in late 2007. The GLAST observatory consists of a spacecraft bus that supports two instruments - the large area telescope (LAT) and the GLAST burst monitor (GBM). Mass and power contingencies for each of these three observatory elements have been allocated and managed based on application of the ANSI/AIAA guide. The correlation of the GLAST experience with the guide is analyzed and suggestions are offered to potential users of the guide for increasing the effectiveness of their application of it on other missions. The results of this paper contribute to the constructive evolution of this important aspect of systems engineering design practice.