The NASA Spirit rover, which has been wandering Mars for the past six years, appears to be permanently stuck in the strange patch of Martian soil it’s been lodged in for the past several months.
With winter approaching, Spirit’s handlers have decided to put the rover into a hibernation mode intended to protect its electronics from temperatures that could drop close to the design limit of negative 67 degrees Fahrenheit.
“The Rover will be like a polar bear hibernating and it could be for many months, on the order of 6 months that the Rover will be in this state,” said John Callas, the Rover project manager at the Jet Propulsion Laboratory, during a media teleconference. “This is not like the Phoenix mission. This rover is electrically active, but it has insufficient power to be awake each day.”
Spirit’s electronics were designed to withstand temperatures of negative 40 Fahrenheit while operating and negative 67 when hibernating. NASA scientists predict that the temperature will drop below negative 40, necessitating taking moves to protect the rover.
“The estimate is that the rover, even though it is getting cold, will stay within its design limits, but those were tested for a brand new rover fresh out of the box and this one has been on the surface for six years,” Callas said. “These will be temperatures that are colder than anything we’ve seen on the surface of Mars.”
Spirit’s sibling, the Opportunity rover, is located closer to the equator and will continue to operate through the winter months.
When the level of solar energy reaches high enough, Spirit will be contacted and wake back up to continue her life not as the rover of yore but as a stationary scientific platform.
Steve Squyres, a planetary scientist at Cornell University and principal investigator for Spirit and Opportunity, tried to put a happy face on this new phase of the mission.
“That imperative to drive is relaxed,” Squyres said. “That enables us to focus on new classes of science that you can only do from a science platform that isn’t moving around a lot.”
In particular, he said that the team would focus on tracking Spirit’s radio signal very precisely, which could allow them to determine whether the Martian core is solid or liquid through a telltale wobble in the planet’s rotation.
“The way that Mars wobbles depends on its internal structure,” said Squyres. “When you go through the math, if Mars has a solid core of iron, it will wobble in a certain well-defined way. But if that core is liquid, it will wobble in an ever-so-slightly different way. And by tracking the signal, we can distinguish between the two.”
The Mars scientists are also excited about the area in which they’ve become stuck.
“The area has the highest concentration of sulfates we’ve seen anywhere on the planet,” Callas said. “We were driving around on a crust of this stuff that was strong enough to support the rover and then we broke through it. We’re very fortunate that this new landing site … turned out to be a good one.”
The sulfates may have been formed by steam vents in the distant Martian past, Squyres said, and subsequently transported by water processes.
Despite the science that can be done at the site, the probable end of Spirit’s career as a mobile unit seemed discouraging to JPL rover driver, Ashley Stroupe. A week and a half ago, the rover team changed their approach to getting the rover unstuck and experienced much greater success.
“We had a tremendous amount of hope,” Stroupe said.
In the end, though, they ran out of time. Now, their main task is positioning the rover to capture the greatest amount of solar energy possible: The rover is currently tilted south, away from the sun in the northern sky. If they can reduce the tilt, Spirit may be able to periodically communicate with Earth throughout the winter. If they can’t, it will be a long, silent winter for the robot.
Image: NASA/JPL. Spirit’s self-portrait.
- Spirit Rover Wiggles Her Wheels
- Spirit’s Low on Mars
- Free Spirit: NASA Recreates Mars Surface to Liberate Rover
- Robot Rescue Party Aiding Mired Martian Rover
- Mars Rover “Spirit” Needs Sunny Slope to Survive Winter
Oh, it’s a sad day for NASA, whose Mars rover “Spirit” is being put into hibernation after a long, long life: 6 years of duty that was only designed for 90 days!