Flight Software Design Guidelines for Enhancing On-Orbit Maintenance
Alexander Calder, Peter H. Kutt · AIAA Infotech@Aerospace Conference · 2009
The goal of on-orbit modification of flight software is to make necessary changes to flight code with as little disruption to mission operations as possible. However, certain characteristics of the software can present obstacles to making localized modifications that are easily installed in flight. These obstacles are not always apparent during software development, and frequently depend on the detailed behavior of the tools used to build the code. In some cases, the obstacles may be related to coding practices that are normally considered desirable. This presentation will describe how lessons learned during on-orbit maintenance have been used at the Goddard Space Flight Center to implement design guidelines during flight software development that help to improve the maintainability of the software after launch. Examples will be given from several missions, including the Solar Dynamics Observatory (SDO) and the Swift Burst Alert Telescope (Swift/BAT). Most of the code in these examples was written in C, linked statically, and built with the GNU compiler/linker tool set. The Swift/BAT code was written in C++ and dynamically linked.