Maas Digital LLC for Cornell University and NASA/JPL via Wikimedia

The Mars rover Opportunity has put itself into a type of standby mode, and NASA managers are waiting for it to resume normal behavior. The rover may have sensed something amiss while it was waiting out the solar conjunction between Mars and Earth.

During conjunction, which is just about over, Mars and Earth are on opposite sides of the sun from each other. The star gets in the way of radio communications between the two planets, so rover drivers put Opportunity and Curiosity in a holding pattern for about a month.

While still in conjunction quiet-time, Opportunity was doing a routine check of atmospheric clarity on April 22. It may have detected something out of the ordinary, or noticed its cameras behaving strangely. “Our current suspicion is that Opportunity rebooted its flight software, possibly while the cameras on the mast were imaging the sun,” Mars Exploration Rover Project Manager John Callas said.

The engineering team sent new commands yesterday and are waiting for Opportunity to resume its mission. The rover has been on Mars for 9 years now, and it was originally supposed to work for three months. Its twin, Spirit, stopped communicating almost four years ago.