After trundling across the Martian surface for 21 months, NASA鈥檚 Opportunity rover has finally reached its target 鈥� the 800-metre-wide Victoria Crater.
The crater is wider and deeper than any other studied by a rover on Mars, which should allow scientists to study further back in time than ever before by looking at older rock layers at the bottom of the crater.
Preliminary images reveal these layers on the crater walls and dunes on the crater鈥檚 floor.
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鈥淭his is a geologist鈥檚 dream come true,鈥� says rover principal scientist Steve Squyres of Cornell University in Ithaca, New York, US. 鈥淭hose layers of rock, if we can get to them, will tell us new stories about the environmental conditions long ago.鈥�
鈥淲e especially want to learn whether the wet era that we found recorded in the rocks closer to the landing site extended farther back in time,鈥� he continues. 鈥淭he way to find that out is to go deeper, and Victoria may let us do that.鈥�
Overcoming obstacles
The Eagle Crater, in which Opportunity landed in 2004, gave geologists about 0.5 metres of layered rock to study. Endurance Crater, where Opportunity spent about six months, provided 7 metres of layers. Victoria Crater appears to be at least 60 metres deep.
Opportunity鈥檚 first stop along the rim will be a region named Duck Bay. From there it will survey two promontories on either side of it to determine which to drive to. From one of these outlooks, Opportunity will make a panoramic image to see whether scientists can safely send the rover into the crater, as they hope to do.
Conceivably, Opportunity could spend its last days in Victoria. It has already defied expectations about its endurance 鈥� it has lasted more than 10 times longer than its estimated 90-day life span and has trekked about 9 kilometres, when it was only expected to travel 600 metres.
It has spent much of its journey and occasionally getting mired in a sand trap.
鈥淲e鈥檙e so proud of Opportunity, the rover that 鈥榯akes a licking but keeps on ticking,'鈥� says Cindy Oda, a rover manager at NASA鈥檚 Jet Propulsion Laboratory in Pasadena, California, US. 鈥淚t continues to overcome all challenges, despite its ageing parts and difficult terrain.鈥�
Unfortunately, Opportunity and its twin, Spirit, on the other side of the planet, will not be able to perform as many operations as usual in October because Mars will pass close to the Sun from Earth鈥檚 point of view, making radio contact difficult.
