NASA's Spirit rover is continuing on course for its scheduled roll-off from the Mars lander sometime early Thursday morning.
Engineers at the Jet Propulsion Laboratory in Pasadena have been rehearsing the roll-off using lander prototypes and are ready to begin the real process overnight Monday. The first step will be to sever the 2-inch cable connecting the rover to the lander using what amounts to a guillotine powered by a small explosive.
The rover will then back up about 8 inches to center itself on the lander, then turn about 45 degrees to its right, said JPL mechanical engineer Kevin Burke. Engineers will then evaluate pictures to make sure that the first part of the turn proceeded correctly. They also want to examine a section of the ground that has previously been covered by one of the solar panels.
If all goes well, they will complete the turn in two more stages overnight Tuesday, leaving the rover ready to roll off the lander early Thursday morning.
On Monday, the NASA team released a sweeping, high-definition panoramic picture of Gusev Crater, constructed of 225 separate images, that would help them identify possible targets for the rover.
By now, JPL researchers are expecting few surprises from the imagery, since they have already received a number of pictures of the site. But they have gotten a couple of surprises anyway.
One was the presence of fractured rocks, "which we haven't seen at any other landing sites," said Michael Malin, an imaging specialist who is part of the rover team. The conventional interpretation, he said, would be that the fractures were caused by a freeze-thaw cycle involving water.
Alternatively, the fracturing could have been caused by impacts when asteroids struck the surface.
Scientists have also been intrigued by the disturbed soil produced when the lander's air bags retracted. "This is data that wasn't anticipated," said geologist John Grotzinger of the Massachusetts Institute of Technology.
Particularly interesting is a thin section of the soil, perhaps a 5-inch square, that broke off and moved intact under the pressure from a retracting bag. Researchers have dubbed it a "magic carpet" and are attempting to figure out what forces are holding it together. It looks like it might be held together by water, but the team discounted such an explanation because any water would have quickly evaporated into the atmosphere.
Malin noted that he was not overly surprised by the magic carpet. "Very fine particles in the absence of water are capable of doing very strange things," he said.
Meanwhile, Mars scientists received bad news from Britain, where the latest attempt to contact the Beagle 2 lander produced no response. The lander reached the Martian surface on Christmas Eve but has not been heard from, and the prospect that it survived is growing increasingly dim.
Principal investigator Colin Pillinger of London's Open University said Monday that no more attempts would be made to contact Beagle 2 until Jan. 22. If the lander is still intact, the lack of signals from Earth will force it into a communications mode in which it will automatically transmit a signal throughout the Martian day.