The Big Dig
Summary (Feb 21, 2004): Both rovers have started to dig into the martian surface. By locking all but one wheel, the rover is equipped to scoop out about a half-wheel diameter (20 cm). By then turning its instrumented robotic arm on the hole, the rover is able to look below the top layer in unprecedented ways.
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The Big Dig
based on NASA/JPL report "We dug a nice big hole on Mars," said Jeffrey Biesiadecki, a rover planner at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
The rover alternately pushed soil forward and backward out of the trench with its right front wheel while other wheels held the rover in place. The rover turned slightly between bouts of digging to widen the hole. "We took a patient, gentle approach to digging," Biesiadecki said. The process lasted 22 minutes.
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Trenches like this can be dug by locking 5 wheels and spinning the rover's remaining one (usually left front).
Image Credit: NASA/JPL |
The resulting trench -- the first dug by either Mars Exploration Rover -- is about 50 centimeters (20 inches) long and 10 centimeters (4 inches) deep. "It came out deeper than I expected," said Dr. Rob Sullivan of Cornell University, Ithaca, N.Y., a science-team member who worked closely with engineers to plan the digging.
Two features that caught scientists' attention were the clotty texture of soil in the upper wall of the trench and the brightness of soil on the trench floor, Sullivan said. Researchers look forward to getting more information from observations of the trench planned during the next two or three days using the rover's full set of science instruments.
Opportunity's twin rover, Spirit, drove 21.6 meters closer to its target destination of a crater nicknamed "Bonneville" overnight Monday to Tuesday. It has now rolled a total of 108 meters (354 feet) since leaving its lander 34 days ago, surpassing the total distance driven by the Mars Pathfinder mission's Sojourner rover in 1997.
Spirit has also begun using a transmission rate of 256 kilobits per second, double its previous best, said JPL's Richard Cook. Cook became project manager for the Mars Exploration Rover Project today when the former manager, Peter Theisinger, switched to manage NASA's Mars Science Laboratory Project, in development for a 2009 launch.
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Opportunity site in panorama at Meridiani
Image Credit: NASA/JPL |
Spirit's drive toward "Bonneville" is based on expectations that the impact that created the crater "would have overturned the stratigraphy and exposed it for our viewing pleasure," said Dr. Ray Arvidson of Washington University in St. Louis, deputy principal investigator for the rovers' science instruments. That stratigraphy, or arrangement of rock layers, could hold clues to the mission's overriding question -- whether the past environment in the region of Mars where Spirit landed was ever persistently wet and possibly suitable for sustaining life.
Both rovers have returned striking new pictures in recent days. Microscope images of soil along Spirit's path reveal smoothly rounded pebbles. Views from both rovers' navigation cameras looking back toward their now-empty landers show the wheel tracks of the rovers' travels since leaving the landers.
Each martian day, or "sol" lasts about 40 minutes longer than an Earth day. Opportunity approaches its first month, while Spirit is set to exceed the two month mark in early March. The two rovers are halfway around Mars from each other.
Related Web Pages
JPL Rovers
Opportunity Puts Hematite on Hold Water Signs Microscopic Imager Gusev Crater Pancam- Surveying the Martian Scene
Mössbauer spectrometer Alpha Proton X-ray Spectrometer
Note: Rocks
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Saturday, February 21, 2004
