London, Nov 15 : Reports indicate that the Mars rover Spirit is still working and is slowly recharging its batteries after a weekend dust storm that caused the craft's power levels to drop to an all-time low.
The storm that hit Spirit came less than two weeks after similar weather in the far north sent NASA's Phoenix Lander to an early grave.
Rover team members were awaiting a sign this week that the craft had survived the storm, which blanketed Spirit's solar panels with dust.
According to a report in New Scientist, during the storm, the amount of energy available to the craft dropped to an unsustainable 89 watt-hours, the lowest level seen since Spirit and its twin, Opportunity, landed on Mars with about 10 times that amount in January 2004.
On November 11, the team commanded Spirit to shut down all unnecessary heaters on the craft, which was supposed to wake up once a day to survey the transparency of the atmosphere.
To conserve its energy, the rover was ordered to wait until November 13 to communicate with the Mars Odyssey spacecraft as it passed by overhead.
But no one was sure if the commands took, or if the craft had entered a 'low-power fault mode.'
That would have shut down the rover's heaters in order to funnel as much energy as possible to the batteries, according to Mars Exploration Rover project manager John Callas of NASA's Jet Propulsion Laboratory in Pasadena, California.
Without the heaters, the rover would have been in a race to charge its batteries before they, and the rover's electronics, were damaged by the extreme cold, he added.
"Either the rover was doing exactly what we told it to do, or it was going to be really bad news," Callas told New Scientist.
But, Spirit beamed back telemetry on November 13 as scheduled, showing still-dusty skies but higher power levels.
The rover collected 161 watt-hours of energy on the Martian day ending November 13.
That energy level is not as high as it was before the storm, when the craft gathered some 240 watt-hours of energy per day. But, Spirit is now collecting enough solar power to replenish its batteries.
"We're above the break-even level," said rover project scientist Bruce Banerdt of JPL. "We're not draining the batteries. We're actually slowing charging them, as long as we don't tell them to do very much," he added.
Spirit is now parked on the sloping edge of a plateau called Home Plate in order to collect more sunlight.