Operational modification of the Mars exploration rovers´ flight software

The Mars exploration rovers (MER) flight software (FSW) was designed from the outset to be modified during operations. Two principal methods were envisioned: modifying (patch) the existing image, or entirely replacing (load) the existing image with a new version. In fact, both methods have been successfully used since the rovers landed in January of 2004. This paper discusses the content of the uplink products that are sent to the rover, the planning of the patch and load activities, the testing of the products and procedures, and the actual operations themselves. Lessons learned and application to future missions are also discussed.