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Mars rover Curiosity bounces back from electrical glitch

NASA's Mars rover Curiosity took this self-portrait, composed of more than 50 images using its robotic arm-mounted MAHLI camera, on Feb. 3. The image shows Curiosity at the John Klein drill site. A drill hole is visible at bottom left.NASA / JPL / MSSS / Marco Di Lorenzo / Ken Kremer

NASA's Mars rover Curiosity is back in action after being sidelined for nearly a week by an electrical problem.

The 1-ton Curiosity rover resumed science operations on Saturday, six days after mission engineers noticed an odd voltage change and stood the robot down to investigate.

"We made a list of potential causes, and then determined which we could cross off the list, one by one," rover electrical engineer Rob Zimmerman, of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement.

The mission team eventually determined that the likely cause of the change in voltage was an internal short in Curiosity's radioisotope thermoelectric generator, which powers the rover by converting the heat of radioactive decay to electricity.

The electrical glitch shouldn't have any lasting effects, mission team members say.

"Due to resiliency in design, this short does not affect operation of the power source or the rover," NASA officials wrote in a Curiosity status update Monday. "Similar generators on other spacecraft, including NASA's Cassini at Saturn, have experienced shorts with no loss of capability."

The voltage difference between Curiosity's chassis and power bus had been about 11 volts since the rover touched down inside Mars' Gale Crater in August 2012. On Nov. 17, engineers noticed that it had dropped to just 4 volts and called a halt to the rover's science operations in response. But the difference returned to 11 volts on Nov. 23, officials said.

Curiosity's main task is to determine if Mars has ever been capable of supporting microbial life. The mission has already answered that question in the affirmative, finding that a site in Gale Crater called Yellowknife Bay was indeed habitable billions of years ago.

Curiosity is now engaged in a long trek to the base of the towering Mount Sharp, whose many layers record a history of Mars' changing environmental conditions over time. The rover should reach Mount Sharp sometime around the middle of next year, mission team members have said.

In its return to science operations over the weekend, Curiosity used its robotic arm to deliver powdered rock to some of its onboard instruments. The rover had stored this powder in its arm since drilling into a target rock called "Cumberland" six months ago, NASA officials said.

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