Mars Rover News: Operations On Hold Up Until Malfunction Is Fixed Remotely
Down here on planet Earth, we have a quick fix solution for nearly everything technical. However, there's no mechanic for millions of miles for Curiosity, NASA's Mars rover that suffered a technical snag on Nov. 17, stalling all operations.
On Sunday, Nov. 17, Curiosity was already into its 456th day on Mars when mission managers received alerts to a "voltage change" between the rover's chassis and the 32-volt power bus designed to distribute electric supply to its systems. According to NASA's Jet Propulsion Laboratory (JPL), "Science observations by NASA's Mars rover Curiosity have been suspended for a few days while engineers run tests to check possible causes of a voltage change detected on Nov. 17."
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However, except for this minor glitch, "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 Mars Science Laboratory Project Manager Jim Erickson at the JPL, based out of Pasadena, Calif. The problem is neither significant enough to cause alarm among mission engineers, nor is this first time that the rover has encountered a technical snag that failed to trigger an automatic reversal to "safe-mode." No one knows if this issue has any connection with Curiosity's recently triggered safe-mode by a computer re-boot early this month.
A "soft short" that Project Manager Jim Erickson referred to is caused when a small amount of electricity leaks through a material that's partially conductive, resulting in loss of some power from a system leading to otherwise inexplicable drop in power. A "hard- short," on the other hand, is caused when two bare wires cross causing, a short circuit that blows a fuse. The good news is that Curiosity is designed to tolerate these types of minor glitches, and they do not cause widespread damage.
For example, on August 5, 2012 shortly after landing inside Gale Crater, engineers noticed a reduction in bus-to-chassis voltage from 16 to 11. The engineers pinned the glitch to a soft short. The inbuilt advantage with Curiosity is that it has "floating bus" design which makes her resilient and operate normally even with 5 volt loss. The short on that occasion was linked to the explosive bolts experienced while separating the rover from skycrane on touching down.
The cause of the Sunday's soft short is yet to be identified even as engineers found that the voltage fluctuated thrice before turning persistent. The current bus-to-chassis voltage is held at 4 volts. Although Curiosity is known for its resilient design, its future tolerance has been decreased according to NASA, indicating a problem with one of the electrical components connected to the short. Meanwhile, till JPL engineers are able to remote fix the glitch, Curiosity can take a break from its normal 24/7 schedule.
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