Opportunity suffered a warm reboot last week. After the flight computer rebooted, the spacecraft went into "safe mode." This error caused the team to miss two Odyssey passes.
The evening pass was missed because the reboot occurred during the Odyssey pass. The morning pass was missed because safe mode enforces the deep sleep behavior.
Real-time commands were sent on sol 597 in order to access the state of the vehicle. Opportunity was healthy and the team regained control of the vehicle. A "lite" master sequence was loaded and sol 597 became a stand down day. On sol 598, the initial system recovery steps were taken and subsystems were tested. All subsystems look good.
This is the first time this fault has been seen on Opportunity. It was seen twice before on Spirit, in May and August of 2004. The decision at that time was to not fix the software bug that causes this problem, and accept the rare interruptions in operations.
The bug is a window of vulnerability in the process of lifting memory write protects and replacing them. The bug allows a 51 microsecond window where another write request can interrupt the first request. When the writes collide, the software protects itself and the vehicle by terminating activities.
This week Opportunity will continue with nominal operations. The rover will continue to move west around Erebus Crater.
Sol-by-sol summaries
