On-board guarded software upgrading for space missions

The authors describe an approach to guarded software upgrading through scenario-based descriptions. Their objectives are to avoid or minimize the unavailability and performance loss of spacecraft/science functions due to software upgrading activities and due to system failure caused by residual faults in an upgraded version. The approach emphasizes: 1) the utilization of nondedicated or inherent system resource redundancies such as an earlier software version and a processor that otherwise would be idle in the mission phase during which software upgrading activities are conducted, and 2) the low-cost efficient error containment and protection mechanisms based on adaptation/extension of the enabling technologies such as checkpointing and message logging