The Spitzer Science Center: using metrics analysis to improve system stability

The Spitzer Science Center (SSC) Software Science Operations System (SOS) is a large, complex software system. Over 1.2 million lines of code had been written for the SOS by time of launch (August 2003). The SSC uses a defect tracking tool called GNATS to enter defect reports and change requests. GNATS has been useful beyond just tracking defects to closure. Prior to launch a number of charts and graphs were generated using metrics collected from GNATS. These reports demonstrated trends and snapshots of the state of the SOS and enabled the SSC to better identify risks to the SOS and focus testing efforts. This paper will focus primarily on the time period of Spitzer's launch and In Orbit Checkout. It will discuss the metrics collected, the analyses done, the format the analyses was presented in, and lessons learned. This work was performed at the California Institute of Technology under contract to the National Aeronautics and Space Administration.