Posted on 08/18/2004 4:33:37 PM PDT by ElkGroveDan
Now that NASA's Mars Exploration Rover Spirit is finally examining bedrock in the "Columbia Hills," it is finding evidence that water thoroughly altered some rocks in Mars' Gusev Crater.
Spirit and its twin, Opportunity, completed successful three-month primary missions on Mars in April and are returning bonus results during extended missions. They remain in good health though beginning to show signs of wear.
On Opportunity, a tool for exposing the insides of rocks stopped working Sunday, but engineers are optimistic that the most likely diagnosis is a problem that can be fixed soon. "It looks like there's a pebble trapped between the cutting heads of the rock abrasion tool," said Chris Salvo, rover mission manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We think we can treat it by turning the heads in reverse, but we are still evaluating the best approach to remedy the situation. There are several options available to us."
Opportunity originally landed right beside exposed bedrock and promptly found evidence there for an ancient body of saltwater. On the other hand, it took Spirit half a year of driving across a martian plain to reach bedrock in Gusev Crater. Now, Spirit's initial inspection of an outcrop called "Clovis" on a hill about 9 meters (30 feet) above the plain suggests that water may once have been active at Gusev.
"We have evidence that interaction with liquid water changed the composition of this rock," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the science instruments on both rovers. "This is different from the rocks out on the plain, where we saw coatings and veins apparently due to effects of a small amount of water. Here, we have a more thorough, deeper alteration, suggesting much more water."
Squyres said, "To really understand the conditions that altered Clovis, we'd like to know what it was like before the alteration. We have the 'after.' Now we want the 'before.' If we're lucky, there may be rocks nearby that will give us that."
Dr. Doug Ming, a rover science team member from NASA's Johnson Space Center, Houston, said indications of water affecting Clovis come from analyzing the rock's surface and interior with Spirit's alpha particle X-ray spectrometer and finding relatively high levels of bromine, sulfur and chlorine inside the rock. He said, "This is also a very soft rock, not like the basaltic rocks seen back on the plains of Gusev Crater. It appears to be highly altered."
Rover team members described the golf-cart-sized robots' status and recent findings in a briefing at JPL today.
Opportunity has completed a transect through layers of rock exposed in the southern inner slope of stadium-sized "Endurance Crater." The rocks examined range from outcrops near the rim down through progressively older and older layers to the lowest accessible outcrop, called "Axel Heiberg" after a Canadian Arctic island. "We found different compositions in different layers," said Dr. Ralf Gellert, of Max-Planck-Institut fur Chemie, Mainz, Germany. Chlorine concentration increased up to threefold in middle layers. Magnesium and sulfur declined nearly in parallel with each other in older layers, suggesting those two elements may have been dissolved and removed by water.
Small, gray stone spheres nicknamed "blueberries" are plentiful in Endurance just as they were at Opportunity's smaller landing-site crater, "Eagle." Pictures from the rover's microscopic imager show a new variation on the blueberries throughout a reddish-tan slab called "Bylot" in the Axel Heiberg outcrop. "They're rougher textured, they vary more in size, and they're the color of the rock, instead of gray," said Zoe Learner, a science team collaborator from Cornell. "We've noticed that in some cases where these are eroding, you can see a regular blueberry or a berry fragment inside." One possibility is that a water-related process has added a coarser outer layer to the blueberries, she said, adding, "It's still really a mystery."
JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Science Mission Directorate, Washington. Images and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University at http://athena.cornell.edu .
This approximate true-color image taken by the Mars Exploration Rover Spirit shows a rock outcrop dubbed "Longhorn," and behind it, the sweeping plains of Gusev Crater. On the horizon, the rim of Gusev Crater is clearly visible. The view is to the south of the rover's current position. The image consists of four frames taken by the 750-, 530- and 430-nanometer filters of Spirit's panoramic camera on sol 210 (August 5, 2004).
This image composite shows some of the holes that the Mars Exploration Rover Opportunity has dug into the slopes of "Endurance Crater" with its rock abrasion tool. The red line indicates the rover's path into the crater, and yellow dots show key abrasion-tool holes. The inset to the right is a false-color image of the holes. Both pictures were taken by Opportunity's panoramic camera.
This movie shows winter clouds drifting across the skies at "Endurance Crater." It consists of three images taken by the Mars Exploration Rover Opportunity's panoramic camera over a period of one minute. Clouds are more common at Meridiani Planum now that winter has arrived.
This image taken by the Mars Exploration Rover Opportunity shows a bizarre, lumpy rock dubbed "Wopmay" on the inner slopes of "Endurance Crater." Scientists say the rock's unusual texture is unlike any others observed so far at Meridiani Planum. Wopmay measures approximately 1 meter (3.3 feet) across. The image was taken by the rover's panoramic camera on sol 195 (Aug. 11, 2004). Opportunity will likely travel to this or a similar rock in coming sols for a closer look at the alien surface.
This image taken by the Mars Exploration Rover Opportunity shows the dunes that line the floor of "Endurance Crater." Small-scale ripples on top of the larger dune waves suggest that these dunes may have been active in geologically recent times. The image was taken by the rover's panoramic camera on sol 198 (Aug. 14, 2004).
Cool.. all different pics FRom than the ones I just posted .. Whew!!! ;-)
Coral???????
Everytime I see or hear the word "Bedrock"; all I can hear in my head is....WIIILLLLMMMMMAAAA ! Did they find any of the bones Dino buried there yet ?
Pillow Lava?
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