— The McMurdo panorama is the largest and most detailed image taken by either Mars rover to date. It shows the view from Spirit's spot in the Columbia Hills (Image: JPL/NASA)
The light-coloured strip of layered rocks, called Home Plate, may be the remains of an explosive volcanic eruption (Image: JPL/NASA)
Scientists hope to further investigate light-coloured sulphates churned up by Spirit's wheels. The sulphates are thought to have formed in the presence of liquid water (Image: JPL/NASA)
The most detailed panoramic view ever obtained on Mars has been returned by NASA's Spirit rover in time to mark its 1000th Martian day, or sol, on the Red Planet.
A total of 1449 individual images representing 500 megabytes of raw data were acquired for the view, called the McMurdo panorama.
Spirit took the images over a span of more than five months, while parked on a slope called Low Ridge Haven during winter in the planet's southern hemisphere. The relatively small amount of winter sunshine meant the rover did not have enough power to drive anywhere.
The panorama shows Spirit's view of part of the Columbia Hills region, where it has made many of its most interesting discoveries (see Water coursed through Martian hills). Many dark, volcanic rocks litter the area.
The tracks Spirit made to get to its current location are visible winding off to the left. In some places they have exposed light-coloured material that is rich in sulphates, which rover scientists believe formed in the presence of water (scroll down for close-up image).
They will be on the lookout for more of this material churned up when Spirit starts driving again. By examining it further, they hope to learn how long ago the water that produced it was present, says rover scientist Ray Arvidson of Washington University in St. Louis, US. "We're not exactly sure what the origin and evolution of this material is," he told New Scientist.
Spirit will make a very short drive in about a week to study new ground with its instruments. About a month from now, it will start a longer drive towards a formation called Home Plate, visible as a light-coloured strip of material in the upper right corner of the image.
Home Plate may be the remains of an explosive volcanic eruption. The explosion may have been triggered by underground water being heated by magma. The resulting build-up of steam may have blasted open the volcano, Arvidson says.
"We're interested in how much water was involved in causing that pressure that would cause the explosive eruption if, in fact, Home Plate is an eroded-down volcano," he says.
Spirit reached its 1000th sol on Wednesday, although like its twin, Opportunity, on the other side of the planet, it was designed to last just 90 sols.
Opportunity is on track to reach the 1000-sol mark in late November. It is perched on the edge of the 800-metre-wide Victoria crater, a scientific treasure trove (see Mars probes snap stunning images of giant crater).
The interior of the crater looks so interesting that the rover may drive in, even if there is no guarantee it will be able to get back out, says rover team member Jim Bell of Cornell University in Ithaca, New York, US. "My guess is that we'd go in anyway," he told New Scientist.
Examining the layered rocks in the crater could give scientists much better insight into the history of water on Mars.
The drive into the crater is probably a month or two away, Bell says: "We need to do some more driving around and sampling the view and the slopes."