OPPORTUNITY, NASA’s second rover, has landed safely – right in the middle of a crater. That’s great news for the geologists on the team as it will allow them to study something they have never had access to before: Martian bedrock.
The landing, on early Sunday morning GMT, was unexpectedly gentle. Within an hour, Opportunity had relayed the first pictures of its surroundings in Meridiana Planum back to NASA’s mission control in Pasadena, California. As expected, they show a very different landscape to anything previously seen by missions that have landed on Mars. The region, in a large zone rich in the mineral haematite, is dark, flat and virtually free of loose rocks and dust.
But the most important thing the scientists saw when Opportunity opened its eyes was that the craft has come down inside a small crater. Its smooth surface should make driving as easy as possible for the roving robot, and dead ahead, about 10 metres away on the edge of the crater, is a large outcrop of light-coloured bedrock. “This is exactly what it looked like in my wildest dreams,” enthused mission head Steven Squyres. “It’s going to be a wonderful place to get to.”
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Why all the excitement? To geologists studying Mars, bedrock is the holy grail. Until now every rock and boulder, every bit of soil and dust ever seen on the surface of Mars came from elsewhere, brought to its resting place by an unknown mix of winds, volcanic eruptions, impact blasts, or the action of waves, floods or glaciers. There is no way to tell just where any of this material came from, or when, making it practically impossible to compile a coherent geological history of the planet.
Not anymore. “Now we have an organised set of layers,” says science-team member Larry Soderblom of the US Geological Survey. “It’s like a library book, with the pages organised in time.” Because the rocks formed locally, the scientists who analyse them up close in the coming weeks will know that they are learning the history of this particular location. “That degree of certitude is priceless,” says Squyres.
And although it is too soon to say how the rocks in this outcrop formed, there is also a chance they will answer the question that has been uppermost on the science team’s mind: did Mars ever have lasting bodies of standing water?
Opportunity will use a microscope and two spectroscopes to study the structure and the mineralogy of the bedrock. If it contains layers of sedimentary rather than volcanic rock, that would be the first unequivocal evidence for the presence of large bodies of liquid water in the past.
Preliminary images from a camera on the European Space Agency’s Mars Express orbiter (see “Latest images reveal Red Planet’s watery past”) suggest finding water-related sediments on most parts of Mars may be tricky. In many areas, volcanic flows appear to have blanketed channels that were carved earlier by rivers, burying any evidence of water. “I’m not saying the rovers can’t do it but I’m saying it will be quite some task,” says Gerhard Neukum, the camera’s lead scientist. “Mars is a complicated planet. It’s not easy to understand its history because different processes occur on top of each other.”
But the Opportunity team may be in luck. An initial assessment suggests it may be one of the few places that does not have such complications. Instead, it seems to be composed of two geological units that both formed in place: the light bedrock, and the dark, fine-grained material that overlies it. That fine soil, draped over the rock, “must be the haematite-bearing unit”, says Squyres.
In fact, he says the two kinds of material inside the 2-metre-deep bowl are so rich in potential, “we could spend most of the mission” just studying this crater. But if the scientists do decide to travel further afield, there is a much bigger crater very close by, about 150 metres across, that could allow them to probe even deeper.
“We have a scientific jackpot,” adds Soderblom. Whatever the origin of the rock and the soil, the geologists are more hopeful than ever that a big chunk of the planet’s mysterious past will finally be revealed.
Additional reporting by Maggie McKee, Darmstadt
Spirit is Revived
After a dire week for NASA’s first lander, Spirit, scientists now hope the rover will resume its explorations soon. Spirit had a computer problem on 21 January, and for two days sent back no new data. On 23 January, project manager Pete Theisinger declared the rover’s condition “critical”, almost certain never to be fully back to normal.
But over the weekend, Spirit slowly started talking again. Its condition is now described as “guarded”, with Theisinger saying a full recovery seems likely after all. A definitive diagnosis was still eluding NASA as żěè¶ĚĘÓƵ went to press, but the focus has narrowed to the craft’s 256 megabytes of flash memory (a form of electronic memory similar to the card in a digital camera), or a bug in the software that controls it. If the flash memory is simply overloaded, then the problem might be solved by deleting old files, and limiting the build-up of new ones.
In any case, the team says the rover should regain its ability to roam, as well as the use of its cameras and scientific instruments, although it is possible that it may have to send back data at a reduced rate. And it may take another week or two to complete the diagnosis and devise the fix.