It has most likely begun its hibernation

Apr 1, 2010 18:01 GMT  ·  By

The Mars Exploration Rover (MER) Spirit may have begun its month-long, low-power hibernation, researchers at the NASA Jet Propulsion Laboratory (JPL), in Pasadena, California, announce. The robot missed a scheduled check-in on March 30, which could mean that its power levels were inadequate to allow for the transmission of data to Earth. If the rover does not relay its signals through the Mars Reconnaissance Orbiter (MRO), using its low-gain antenna, then it needs to use its high-gain one, which drains a lot of power.

The fact that Spirit missed the check-in came as no surprise for the JPL team managing the machine. The engineering team here developed recent power-supply projections, which showed that the machine might go into its low-power hibernation mode around this date. It announces, though, that the internal clock on the MER component is still operational. All other activities and communications have ceased, however, as the team plans to conserve as much power as possible. Over the coming months, the Sun will spend very little time in the sky above Spirit's location, and the robot needs every bit of sunlight it can get, if it is to survive another Martian winter.

The internal clock, heating and battery recharging are the only active processes going on at this point, the team reports. A communication schedule has been set up for Spirit as it endures the Martian winter, but the rover has been “told” not to attempt to stick to it if it experiences inadequate power supplies. Periodically, its onboard computer will check the battery status. If sufficient electricity is generated, then the machine will attempt to send status reports to the JPL crew.

“We may not hear from Spirit again for weeks or months, but we will be listening at every opportunity, and our expectation is that Spirit will resume communications when the batteries are sufficiently charged,” JPL MER Project Manager John Callas, who is in charge of the team taking care of both Spirit and its twin Opportunity, explained. He says that the winter solstice will take place on Mars in mid-May, which means that this is the most critical time in Spirit's new trial. The main concern the group has is the rover's solar panels, which have a lot of dust on them. This is bound to hinder the absorption of the sunlight, at a time when this is absolutely essential.

“The temperature limit was for a new rover. We now have an older rover with thousands of thermal cycles on Mars, so the colder temperatures will be a further stress. We are checking other less-likely possibilities for the missed communication, but this probably means that Spirit tripped a low-power fault sometime between the last downlink on March 22 and yesterday. The recent downlinks had indicated that the battery state of charge was decreasing, getting close to the level that would put Spirit into this hibernation,” Callas said a few days ago.