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| This approximate true-color image taken by the panoramic camera on the Mars Exploration Rover Opportunity shows the impact crater known as "Endurance," roughly 130 meters (430 feet) across and, from the highest point on the rim, more than 20 meters (66 feet) deep. Opportunity is perched 40 centimeters (15.7 inches) away from the crater's edge. Copyright © Cornell University Click on the image for a high-resolution version (3000 x 587 pixels, 372K), or "onClick="window.open('../../Utilities/notice.html','cawindow','resizable=yes,toolbar=no,status=no,scrollbars=no,menubar=no,width=200,height=210');">Click here for the full size version (really big, 24MB!). If you have a pair of red and blue glasses there is a black and white 3D version |
After a six-week trek across Martian flatlands, the Mars rover Opportunity is standing on the rim of a stadium-sized crater, lined with multiple layers of exposed bedrock.
"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," Cornell astronomer Steven Squyres said about a color panorama of Endurance crater released at a news conference yesterday (May 6) at a press briefing at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif. Squyres, professor of astronomy at Cornell, is the principal investigator for the science instruments on both Opportunity and its twin rover, Spirit.
The layers of bedrock lining the deep crater, and their thickness, could 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 much shallower Eagle crater where Opportunity spent its first eight weeks on Mars.
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.
On the other hand, Opportunity might be asked, in essence, to commit suicide. Scientists might send it down into the crater with the expectation that it would not be able to climb 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 at NASA headquarters in Washington, D.C.
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 Endurance, the deepest crater nearby. 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 could 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."
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