NASA engineers have brought a long-running Mars rover out of stand-by mode after the robot ran into trouble last month.

The Mars rover Opportunity is back up and running, according to Guy Webster, a spokesman for NASA.

"Confirmation has been received that Opportunity is back under ground control, executing a sequence of commands sent by the rover team," said Webster, in an email to Computerworld. "The rover is no longer in stand-by mode and has resumed normal operations."

Opportunity, which has been working on Mars for more than nine years, put itself into stand-by mode while it was out of communication with NASA engineers, who normally send it daily instructions. Early in April, communications began to break up and then stopped all together as the sun moved almost directly into the path between Earth and Mars in an event called a solar conjunction, which occurs about every two years.

During the nearly monthlong communications blackout, NASA scientists left instructions for the two working robotic rovers, Curiosity and Opportunity, as well as the orbiters, Odyssey and the Mars Reconnaissance Orbiter, to do minimal work. The rovers remained stationary.

The solar conjunction is just ending, and as communications began to be restored, NASA on Saturday learned of Opportunity's troubled status.

On Monday, NASA programmers sent new commands to Opportunity to try to get the robotic rover to resume operations. Engineers received confirmation on Wednesday that the commands worked and that Opportunity is back to working normally.

Opportunity and its robotic twin, Spirit, arrived on Mars early in 2004. While Opportunity is still working, Spirit was given up for dead in 2011 after it got stuck in dirt on the planet's surface a year earlier.

In 2010, Opportunity was upgraded with artificial intelligence software to enable the robotic rover to make some of its own decisions about what rocks or geological formations it should analyze.

Opportunity and Spirit, which were both designed to work for just three months, are considered to be two of NASA's most successful robotic projects.

This article, Long-distance CPR: NASA revives Mars rover Opportunity, was originally published at Computerworld.com.

Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, on Google+ or subscribe to Sharon's RSS feed . Her email address is sgaudin@computerworld.com.

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