Mars Rover Suffers Glitch, Operations On Hold
The issue with roving on another planet is that should something go wrong, there’s no mechanic for millions of miles and any fix to an electrical problem needs to be found remotely. On Sunday, NASA’s Mars rover Curiosity has experienced such a glitch, ceasing all roving and science operations.
On Nov. 17, Curiosity’s 456th day (or sol) on Mars, mission managers were alerted to a “voltage change” between the rover’s chassis and 32-volt power bus that distributes electricity to systems throughout the rover, a JPL news release reports. Although the problem is significant enough to warrant close inspection by engineers, this isn’t the first time the rover has suffered a glitch of this nature and it did not trigger an automatic “safe-mode.” Also, there is “no indication” to suggest that this event has any connection to Curiosity’s safe-mode that was triggered by a computer re-boot earlier this month.
“The vehicle is safe and stable, fully capable of operating in its present condition, but we are taking the precaution of investigating what may be a soft short,” said Jim Erickson, Mars Science Laboratory Project Manager at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.
As opposed to a “hard” short where two bare wires cross, creating a short-circuit and blowing a fuse, a “soft” short is caused when a a small amount of electricity leaks through a material that’s partially conductive, bleeding some power from a system. The result can be a drop in power that may not otherwise be explained.
Fortunately, Curiosity is a tough old ‘bot and engineers designed some tolerance into her power systems to make sure glitches like these don’t cause widespread damage.
Shortly after landing inside Gale Crater on Aug. 5, 2012, engineers identified a soft short as the culprit of a reduction in bus-to-chassis voltage from 16 to 11 volts. Curiosity’s “floating bus” design makes the robot resilient to such a reduction, allowing it to operate as normal despite the 5 volt loss. On that occasion, the short was identified as being associated with the explosive bolts that separated the rover from its skycrane as it touched down. The cause of the soft short on Sunday, however, has yet to be identified, though engineers deduce that the voltage fluctuated three times before becoming persistent. The bus-to-chassis voltage is now holding at 4 volts.
Although this may sound dramatic, Curiosity is designed to continue to work with huge tolerances of voltage change, but NASA admits that the robot’s future tolerance has been decreased and this glitch could indicate a problem with one of the electrical components associated with the short.
So, while JPL engineers troubleshoot the problem from afar, Curiosity remains parked up, taking a break from science and roving operations until the most likely culprit for the soft short is identified. Enjoy the rest while you can, Curiosity, you have a long climb ahead of you.
Image: One of the last raw images from Curiosity’s Navcam to be uploaded to the mission’s website on Nov. 17. Credit: NASA/JPL-Caltech(Nov 20, 2013 04:48 PM ET // by Ian O'Neill)
