The rovers on Mars this month were under a command moratorium as Mars passed behind the sun, an event known as solar conjunction. Now that the solar conjunction has ended, researchers have found something amiss with Mars rover Opportunity.

Mission controllers this week found Opportunity in a standby mode. NASA has stated that it appears the rover “sensed something amiss” during a camera check on April 22 and entered standby. Team members have prepared commands for Opportunity to bring it back to full operative status.

“Our current suspicion is that Opportunity rebooted its flight software, possibly while the cameras on the mast were imaging the sun,” said John Callas, Mars Exploration Rover Project Manager at NASA’s Jet Propulsion Laboratory. “We found the rover in a standby state called automode, in which it maintains power balance and communication schedules, but waits for instructions from the ground. We crafted our solar conjunction plan to be resilient to this kind of rover reset, if it were to occur.”

Opportunity was one of two rovers that landed on Mars in 2004 as part of the Mars Exploration Rover Project. The other rover, Spirit, became stuck in soft soil in 2009, and ceased communications in 2010.

The newest rover on Mars, Curiosity, is reported to be fully operational following the solar conjunction. Researchers are planning on sending it commands starting tomorrow.

(Image courtesy ASA/JPL-Caltech)