• E-mail
• Print
• Comment
• Font Size
• Digg
• del.icio.us
• Discuss article

Opportunity Rover May Be Sent Into Deep Crater

Posted on: Friday, 7 May 2004, 06:00 CDT

Jet Propulsion Lab -- Scientists and engineers celebrated when they saw the first pictures NASA's Opportunity sent from the rim of a stadium- sized crater that the rover reached after a six-week trek across martian flatlands.

Multiple layers of exposed bedrock line much of the inner slope of the impact crater informally called "Endurance."

Such layers and their thicknesses may reveal what the environment on Mars was like before the salty standing body of water evaporated to produce the telltale rocks that were explored in the tiny "Eagle" Crater. That’s where Opportunity spent its first eight weeks on Mars.

"It's the most spectacular view we've seen of the martian surface, for the scientific value of it but also for the sheer beauty of it," Dr. Steve Squyres of Cornell University, Ithaca, N.Y., said about a color panorama of Endurance Crater released at a news conference today at NASA's Jet Propulsion Laboratory, Pasadena, Calif. He is the principal investigator for the science instruments on both Opportunity and its twin Mars Exploration Rover, Spirit.

In coming days, Opportunity will circle the rim of Endurance, observing the crater's interior from various angles. Scientists and engineers have begun to identify interesting science targets and assess how difficult it would be for the rover to descend partway into the crater and climb back out.

"We will need to decide whether the science is compelling enough to send the rover into a crater it might never leave, or whether to explore other sites first before entering Endurance," said Orlando Figueroa, director of the Mars Exploration Program, NASA Headquarters, Washington.

At Eagle Crater, an outcrop of bedrock only about the height of a street curb yielded evidence that the site was once covered by a body of salty water deep enough to splash in.

"That was the last dying gasp of a body of water," Squyres said. "The question that has intrigued us since we left Eagle Crater is what preceded that. Was there a deep body of water for a long time? Was there a shallow, short-lived playa? We don't know."

The strategy for seeking answers is to examine older rocks from deeper layers, so Opportunity was sent on drives totaling about 800 meters (half a mile) to reach the deepest crater nearby, Endurance.

This crater excavated by the impact of a tiny asteroid or a piece of a comet is about 130 meters (430 feet) wide and, from the highest point on the rim, more than 20 meters (66 feet) deep, 10 times as deep as Eagle.

An exposure of outcrop in a cliff high on the inner wall across from the rover's current position reveals a stack of layers 5 to 10 meters (16 to 33 feet) tall. Other exposures around the inner slope of the crater may be more accessible than the cliff, and chunks from the same layers may have been thrown out onto surrounding ground by the crater-forming impact.

"There is a rock unit below what we saw at Eagle Crater," Squyres said. "It looks fundamentally different from anything we've seen before. It's big. It's massive. It has a story to tell us."

Brian Cooper, leader of JPL's squad of rover drivers for Spirit and Opportunity, said the initial view of the crater doesn't settle accessibility questions yet.

"The slope right in front of us averages 18 to 20 degrees. Getting into the crater is no problem, but we have a lot more work to do to assess whether we could get back out. That depends on soil properties and slippage, as well as slope."

The planned circuit around the rim will also require careful navigation. "If you don't go close enough to the lip, you can't look in, but if you go too far, you could fall in," he said. "We're going to have a very interesting few weeks."

When NASA sent astronauts to the lunar surface more than 30 years ago, it was decided not to allow them to enter craters as fresh and steep as Endurance, but Opportunity may be able to do what no human has done before on another planet.

This image shows Opportunity in comparison to the impressive impact crater dubbed "Endurance." Credit: NASA/JPL

This image highlights a feature called "Karatepe" within the impact crater known as "Endurance." Image credit: NASA/JPL/Cornell

This map illustrates the Mars Exploration Rover Spirit's position as of sol 112 (April 26, 2004), near the crater called "Missoula." Credit: NASA/JPL

'Columbia Hills' on the Horizon

Halfway around Mars, Spirit is now approximately 1.7 kilometers (1 mile) away from the base of the "Columbia Hills" after three long sols of driving. Its odometer currently reads 1,566 meters (.97 miles) and counting.

Sol 118 was a record-breaking driving sol for Spirit. The Gusev Crater rover moved 92.4 meters (303 feet) across the surface in one sol, breaking its previous record of around 90 meters (295 feet). The Opportunity rover still has Spirit beat with a one-sol driving record of 140 meters (459.3 feet).

Sol 119 proved to be a more difficult sol for Spirit. An uplink configuration error prevented the sequence load from successfully getting on board the rover. Rover controllers took advantage of the down day by deleting afternoon communication sessions and enabling the rover to charge its battery during a long afternoon nap.

It was back to business as usual on sol 120. Before embarking on its drive, Spirit imaged a rock called "Tulula" with the panoramic camera. The rover then successfully executed a blind drive before using the autonomous navigation system to continue into uncharted territory.

After reaching the time-of-day driving limit, Spirit turned and performed penultimate (next to last stop) imaging. The next move would have taken the rover 85 centimeters (33.5 inches) to its ultimate stopping point, but did not execute because Spirit was facing a small sand ridge that was perceived as a hazard.

Without a penultimate/ultimate image pair, rover controllers could not be sure that the area underneath the rover was clear of hazards for instrument arm deployment.

As a result, Sol 121 will be another driving sol that controllers hope will place Spirit in a suitable location to use the instruments on its instrument deployment device.

-----

Follow every step of the Mars Exploration Rover Mission with RedNova. Click here to learn more...

-----

On the Net:

Mars Exploration Rover Mission

NASA

Cornell University Athena

More science, space, and technology from RedNova

Copyright © 2004 The Associated Press. All rights reserved. The information contained in the AP News report may not be published, broadcast, rewritten or redistributed without the prior written authority of The Associated Press.

More News in this Category