After several days of Curiosity being in safety mode, NASA engineers have resumed communication with their Mars rover.

NASA announced that engineers are working to restore the robotic rover, which landed on Mars in August 2012, to full working mode.

Curiosity is stable and not in danger.

The rover, which discovered that ancient Mars held key chemicals needed for life as well as evidence of ancient water flows, put itself into safe mode on July 2.

NASA said Curiosity's team has not yet pinpointed why the robot took that precautionary step, which meant it stopped all activities that weren't necessary for keeping itself running on a basic level.

Engineers are requesting the rover send home data that should help them diagnose the problem.

"Engineers are working to determine the cause of safe-mode entry," NASA noted on its website. "Preliminary information indicates an unexpected mismatch between camera software and data-processing software in the main computer."

Before this computer glitch, Curiosity put itself into safe mode on three other occasions -- all of them in 2013.

NASA sent Curiosity to Mars to try to find evidence that the Red Planet had at any point in its history been capable of sustaining life, even in microbial form.

The rover hit that goal in its first year on Mars when it discovered evidence that more than 3 billion years ago at least one area of the planet had fresh-water lakes and rivers.

Just last week, NASA approved a two-year extension to Curiosity's work.

NASA also has the rover Opportunity working on Mars. Opportunity's sibling, Spirit, has stopped working.