NASA to send little Mars rover into gaping crater

WASHINGTON (Reuters) - NASA will send its Mars rover Opportunity into a gaping Martian crater in July to seek clues about the planet's bygone environment despite risks to the plucky little vehicle, officials said on Thursday.

There is the chance the six-wheeled fact-gathering robot will be unable to handle the terrain inside Victoria Crater or get out once it gets in, they said.

But U.S. space agency officials said they did not view this as a suicide mission for Opportunity and looked forward to the potential for a deeper understanding of Earth's planetary neighbor. It is one of two rovers now on the Martian surface.

Opportunity is due to enter the crater either July 7 or July 9, according to John Callas, rover project manager at NASA's Jet Propulsion Laboratory in Pasadena, California.

"We know that the rewards are worth the risk," added Alan Stern, associate administrator of NASA's science mission office. "Entering this crater does come with some unknowns."

"We can't be certain about the terrains and the footing down in the crater until we go there. We can't guarantee, although we think we're likely to come back out of the crater," Stern told reporters.

Victoria Crater, near the Martian equator, is about half a mile wide and was formed by the primordial impact by a space rock on the planet's surface.

Mission scientists have been directing Opportunity to roll around the rim of the crater, exploring layered rocks and looking for the easiest place to make its entrance. They settled on a rock-paved slope on an alcove dubbed Duck Bay.

Callas said Duck Bay has entry slopes of no more than 20 degrees, with the rover able to handle a slope as steep as 32 degrees. Callas said there is confidence the rover can travel safety at least 330 feet into the crater.

NOW OR NEVER

The rover, originally intended to operate for three months, has kept going strong for 12 times as long. The scientists have carefully plotted its mission to explore Victoria's secrets to enable an eventual exit but acknowledge that the rover could become trapped inside or lose some capabilities.

With the rover aging, it was now or never for this descent into the crater, they said.

The scientists want Opportunity to gather data on the composition of material in the crater's depths that may provide further evidence about an ancient environment on Mars that many experts think was wet and potentially habitable by at least microbial life forms.

As it goes deeper into the giant hole, it will be able to examine more ancient rocks in the crater's exposed walls.

"The rovers have been amazingly resilient to date. They're hardy little vehicles. We're quite confident," Callas said.

The crater is about five times wider than Endurance Crater, which Opportunity devoted more than six months exploring in 2004. Victoria Crater is about 4 miles south of the spot where Opportunity landed in January 2004.

Callas said the Victoria Crater mission was an easier jaunt for Opportunity than going into Endurance Crater because the initial slopes are somewhat less steep and the scientists have more experience guiding it in such terrain.

The robot's discoveries in Endurance Crater revealed evidence of the water-rich ancient history of Mars. Opportunity started rolling toward Victoria from Endurance 30 months ago.