Mars Odyssey Enters Safe Mode
NASA Mars Exploration Rover Update 8 April 2005
“Sol 446: Spirit and Opportunity use NASA’s Mars Odyssey orbiter as their main communications link between Mars and Earth. On April 2, Odyssey entered “safe mode,” which is a protective state a spacecraft automatically enters when onboard fault protection software instructs the spacecraft to disregard its onboard sequence of commands and wait for instructions from the ground. As a result, relay communication with the rovers was suspended, and Spirit did not receive any data from sols 444 and 445. With an unknown status of the rover after its drive, the Spirit team restricted rover operations to remote sensing.”