Article Posted on : - Nov 28, 2013

Artist concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life. Photo: NASA/JPL-Caltech

WASHINGTON (PTI): NASA's Mars rover Curiosity has resumed full science operations after a successful diagnosis of the likely cause of a change in voltage on the six-wheeled robot.

The one tonne rover resumed operations on November 23, NASA said.

Activities over the weekend included use of Curiosity's robotic arm to deliver portions of powdered rock to a laboratory inside the rover.

The powder has been stored in the arm since the rover collected it by drilling into the target rock "Cumberland" six months ago.

Several portions of the powder have already been analysed. The laboratory has flexibility for examining duplicate samples in different ways.

The decision to resume science activities resulted from the success of work to diagnose the likely root cause of a November 17 change in voltage on the vehicle.

The voltage change itself did not affect the rover safety or health. The vehicle's electrical system has a "floating bus" design feature to tolerate a range of voltage differences between the vehicle's chassis - its mechanical frame - and the 32-volt power lines that deliver electricity throughout the rover. This protects the rover from electrical shorts.

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

Science operations were suspended for six days while this analysis took priority.

The likely cause is an internal short in Curiosity's power source, the Multi-Mission Radioisotope Thermoelectric Generator.

Due to resiliency in design, this short does not affect operation of the power source or the rover.

Following the decision to resume science activities, engineers learned that the rover had returned to its pre-November 17 voltage level.

This reversal is consistent with their diagnosis of an internal short in the generator, and the voltage could change again.