In just a few days, the Spirit rover will celebrate six incredible years on Mars. But JPL put out a press release today, as well as the video above, saying the outlook for Spirit’s survival is not good. Being stuck in a sand trap with wheels that aren’t working well are challenges to Spirit’s mobility that could prevent the rover team from using a key survival strategy — positioning the rover’s solar panels to tilt toward the sun to collect power for heat to survive the severe Martian winter. “The highest priority for this mission right now is to stay mobile, if that’s possible,” said Steve Squyres, principal investigator for the rovers.
I’m still holding out hope, however, that the rover team will work another miracle, and that 2010 will be another happy year for Spirit on Mars — see the image below created by Stu Atkinson.
But if mobility is not possible, the next priority is survival. To to that, the rover team will attempt to improve the rover’s tilt, while Spirit is able to generate enough electricity to turn its wheels. Spirit is in the southern hemisphere of Mars, where it is autumn, and the amount of daily sunshine available for the solar-powered rover is declining. This could result in ceasing extraction activities as early as January, depending on the amount of remaining power. Spirit’s tilt, nearly five degrees toward the south, is unfavorable because the winter sun crosses low in the northern sky.
Unless the tilt can be improved or luck with winds affects the gradual buildup of dust on the solar panels, the amount of sunshine available will continue to decline until May 2010. During May, or perhaps earlier, Spirit may not have enough power to remain in operation.
“At the current rate of dust accumulation, solar arrays at zero tilt would provide barely enough energy to run the survival heaters through the Mars winter solstice,” said Jennifer Herman, a rover power engineer at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
The team is evaluating strategies for improving the tilt even if Spirit cannot escape the sand trap, such as trying to dig in deeper with the wheels on the north side. In February, NASA will assess Mars missions, including Spirit, for their potential science versus costs to determine how to distribute limited resources. Meanwhile, the team is planning additional research about what a stationary Spirit could accomplish as power wanes.
“Spirit could continue significant research right where it is,” said Ray Arvidson of Washington University in St. Louis, deputy principal investigator for the rovers. “We can study the interior of Mars, monitor the weather and continue examining the interesting deposits uncovered by Spirit’s wheels.”
A study of the planet’s interior would use radio transmissions to measure wobble of the planet’s axis of rotation, which is not feasible with a mobile rover. That experiment and others might provide more and different findings from a mission that has already far exceeded expectations.