London: Reports indicate that a second wheel may now be broken on NASA’s Spirit rover, dampening hopes for freeing the robot from a sand trap it has been trapped in for seven months on Mars.
Spirit has been struggling to escape from a patch of soft, sandy soil since April. Its three left wheels are almost entirely buried and have little traction, and its right-front wheel is of no use, as it seized up permanently in 2006.
Now, according to a report in New Scientist, Spirit’s right-rear wheel is also having problems and may be permanently disabled, increasing the rover’s risk of freezing to death in the coming winter.
The right-rear wheel stalled on 28 and 21 November during attempts to start driving the rover out of the sand trap.
Each wheel has its own motor, and the rover team commanded Spirit to try to spin the wheel again during a series of tests on 3 and 4 December – but it did not budge.
In the previous stalls, the wheel had at least moved a little bit before unexpectedly stopping. But no motion at all was detected in the tests.
“That’s troubling,” said rover project manager John Callas of NASA’s Jet Propulsion Laboratory in Pasadena, California. “It’s conceivable we’re witnessing a deterioration on the wheel,” he added.
If the wheel cannot be coaxed into working again, then Spirit will likely be trapped forever, according to Callas.
“It was questionable whether we could get a five-wheel-driving rover out. If we have a four-wheel-driving rover with only one driving wheel on the right-hand side, then extracting the rover from its current embedded location is unlikely,” he said.
“Spirit could die if it remains stuck when winter arrives six months from now at the rover’s location in Mars’s southern hemisphere,” he added.
In previous winters, Spirit rested on slopes that angled its solar arrays in a way that captured as much sunlight as possible.
That allowed the rover to power heaters designed to keep its electronic innards from freezing.
But, Spirit’s solar panels are not currently at a good angle to maximise sunlight.
Meanwhile, dust is slowly accumulating on the panels, reducing their efficiency. If the rover is unable to move, it could run out of power and die in the frigid Martian night.