NASA's Mars rover Curiosity has returned to active status and is on track to resume science investigations, following two days in a precautionary standby status, "safe mode."

Next steps will include checking the rover's active computer, the B-side computer, by commanding a preliminary free-space move of the arm. The B-side computer was provided information last week about the position of the robotic arm, which was last moved by the redundant A-side computer.

The rover was switched from the A-side to the B-side by engineers on Feb. 28 in response to a memory glitch on the A-side. The A-side now is available as a back-up if needed.

"We expect to get back to sample-analysis science by the end of the week," said Curiosity Mission Manager Jennifer Trosper of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Engineers quickly diagnosed the software issue that prompted the safe mode on March 16 and know how to prevent it from happening again.

Other upcoming activities include preparations for a moratorium on transmitting commands to Curiosity during most of April, when Mars will be passing nearly directly behind the sun from Earth's perspective. The moratorium is a precaution against interference by the sun corrupting a command sent to the rover.

earlier report New Curiosity 'Safe Mode' Status Expected to be Brief
NASA's Mars rover Curiosity is expected to resume science investigations in a few days, as engineers quickly diagnosed a software issue that prompted the rover to put itself into a precautionary standby status over the weekend.

Curiosity initiated this automated fault-protection action, entering "safe mode" at about 8 p.m. PDT (11 p.m. EDT) on March 16, while operating on the B-side computer, one of its two main computers that are redundant to each other. It did not switch to the A-side computer, which was restored last week and is available as a back-up if needed. The rover is stable, healthy and in communication with engineers.

The safe-mode entry was triggered when a command file failed a size-check by the rover's protective software. Engineers diagnosed a software bug that appended an unrelated file to the file being checked, causing the size mismatch.

"This is a very straightforward matter to deal with," said the project manager for Curiosity, Richard Cook of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We can just delete that file, which we don't need any more, and we know how to keep this from occurring in the future."

The mission's science observations have been on hold since a memory glitch on the A-side computer on Feb. 27, which prompted controllers to command a swap from the A-side computer to the B-side computer. That operator-commanded swap put Curiosity into safe mode for two days. The rover team restored the availability of the A-side as a backup and prepared the B-side to resume full operations.

Cautiously bringing Curiosity out of safe mode status on the B-side is expected to take a couple of days. A four-week moratorium on sending commands to the rover will begin April 4 due to solar system geometry of Mars passing nearly directly behind the sun from Earth's perspective. The moratorium is a precaution against interference by the sun corrupting a command sent to the rover.