After getting out of a recent reboot into safe-mode status caused by some anomaly, the Mars Curiosity rover has halted operations for a few days after a new problem has been discovered: a soft short.* NASA engineers are running tests now.
But fear not, my fellow cosmonerds. According to Mars Science Laboratory Project Manager Jim Erickson at NASA's Jet Propulsion Laboratory, "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."
The voltage fluctuation was detected "between the chassis and the 32-volt power bus that distributes electricity to systems throughout the rover" on November 17. "The level had been about 11 volts since landing day, and is now about 4 volts."
This is not the first soft short experienced by Curiosity. There was another before and after landing, related to the "explosive-release devices used for deployments."
The good news: "The rover's electrical system is designed with the flexibility to work properly throughout that range and more — a design feature called floating bus."
The bad news: "Soft shorts reduce the level of robustness for tolerating other shorts in the future, and they can indicate a possible problem in whichever component is the site of the short."
So this is kind of worrying long term, although there's no immediate danger for the rover.
According to NASA, "analysis so far has determined that the change appeared intermittently three times during the hours before it became persistent." NASA's engineers will now check all the systems for potential root causes during the next few days.
* NASA's definition of a "soft" short: "a leak through something that's partially conductive of electricity, rather than a hard short such as one electrical wire contacting another."