March 5, 2013
Curiosity Is Back On Track After Memory Glitch Forced JPL To Switch Computers
Lawrence LeBlond for redOrbit.com - Your Universe Online
On February 28, a team of engineers at the Jet Propulsion Laboratory (JPL) in California switched their Mars Curiosity rover over to a redundant onboard computer after discovering a memory issue within the main computer system. That swap put Curiosity into “safe mode,” allowing the team to investigate the main computer before returning the rover back to a normal routine.
Like most spacecraft, Curiosity was developed with two redundant main computers in case one fails. Each of the computers, an A-side and a B-side, have redundant subsystems, as well, that are linked to one computer or the other. The rover operated on its B-side through most of the trip to Mars, switching over to the A-side shortly before landing on the Red Planet last August. It remained on the A-side until just last week when the glitch occurred.
With the A-side computer now labeled as inactive, B-side becomes the main computer.
"We are making good progress in the recovery," said Mars Science Laboratory Project Manager Richard Cook, of NASA's JPL. "One path of progress is evaluating the A-side with intent to recover it as a backup. Also, we need to go through a series of steps with the B-side, such as informing the computer about the state of the rover -- the position of the arm, the position of the mast, that kind of information."
Communication with Curiosity was not affected when the issue was discovered last Wednesday. However, the craft could not transmit recorded data back to Earth. It did send current status information that revealed the computer had not switched to its usual daily sleep mode as scheduled, which helped engineers pinpoint the issue to its memory databank.
The team still does not know the exact reason why the memory failed, but one theory revolves around space radiation.
This past week´s memory issue has been the biggest single crisis to befall Curiosity since it began its “Seven Minutes of Terror” descent onto Mars on August 5, 2012.
Curiosity has been hard at work over the past several months exploring the areas inside the Gale Crater looking for signs Mars may have once been a habitable environment for microbial life to exist. The rover grabbed its first sample of Martian soil back in October and just last month drilled its first rock.
The Mars Science Laboratory and Curiosity project is operated by the JPL, a division of the California Institute of Technology in Pasadena. It manages the project for NASA´s Science Mission Directorate in Washington.