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PASSPORT TO KNOWLEDGE - To MARS with MER
Mars Orbiter Sees Rover Tracks Among Thousands of New Images
September 27, 2004
NASA's Mars Global Surveyor, starting its third mission extension this week after seven years of orbiting Mars, is using an innovative technique to capture pictures even sharper than most of the more than 170,000 it has already produced.
One dramatic example from the spacecraft's Mars Orbiter Camera shows wheel tracks of NASA's Mars Exploration Rover Spirit and the rover itself. Another tells scientists that no boulders bigger than about 1 to 2 meters (3 to 7 feet) are exposed in giant ripples created by a catastrophic flood.
Those examples are available online at http://www.msss.com/mars_images/moc/2004/09/27/ and http://mars.jpl.nasa.gov/mgs. In addition, about 24,000 newly catalogued images that Mars Global Surveyor took between October 2003 and March 2004 have been added to the Mars Orbiter Camera Image Gallery at http://www.msss.com/moc_gallery/. These include additional pictures of the Mars Exploration Rover sites seen from orbit.
Wheel tracks left by NASA's Mars Exploration Rover Spirit, and even the rover itself, are visible in this image from the Mars Orbiter Camera on NASA's Mars Global Surveyor orbiter.
"Over the past year and a half, the camera and spacecraft teams for Mars Global Surveyor have worked together to develop a technique that allows us to roll the entire spacecraft so that the camera can be scanned in a way that sees details at three times higher resolution than we normally get," said Dr. Ken Edgett, staff scientist for Malin Space Science Systems, San Diego, Calif., which built and operates the Mars Orbiter Camera. The technique adjusts the rotation rate of the spacecraft to match the ground speed under the camera.
"The image motion compensation is tricky and the spacecraft does not always hit its target. However, when it does, the results can be spectacular," Edgett said.
The Mars Orbiter Camera acquires the highest resolution images ever obtained from a Mars-orbiting spacecraft. During normal operating conditions, the smallest objects that can be resolved on the martian surface in these images are about 4 to 5 meters (13 to 16 feet) across. With the adjusted-rotation technique, called "compensated pitch and roll targeted observation," objects as small as 1.5 meters (4.9 feet) can be seen in images from the same camera. Resolution capability of 1.4 meters (4.6 feet) per pixel is improved to one-half meter (1.6 feet) per pixel. Because the maneuvers are complex and the amount of data that can be acquired is limited, most images from the camera are still taken without using that technique.
Researchers' goal in taking this image was to look for boulders in the large ripples formed by an ancient catastrophic flood in Mars' Athabasca Vallis.
Mars Global Surveyor began orbiting Mars on Sept. 12, 1997. After gradually adjusting the shape of its orbit, it began systematically mapping the planet in March 1999. The Mars Orbiter Camera's narrow-angle camera has now examined nearly 4.5 percent of Mars' surface, including extensive imaging of candidate and selected landing sites for surface missions. The Mars Orbiter Camera also includes a wide-angle camera that observes the entire planet daily.
"Mars Global Surveyor has been productive longer than any other spacecraft ever sent to Mars, since it surpassed Viking Lander 1's longevity earlier this year and has returned more images than all past Mars missions combined," said Tom Thorpe, project manager for Mars Global Surveyor at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The mission will complete its 25,000th mapping orbit on Oct. 11.
Principal goals for the orbiter's latest mission extension, beginning Oct. 1, include continued weather monitoring to form a continuous set of observations with NASA's next Mars mission, Mars Reconnaissance Orbiter, scheduled to reach the red planet in 2006; imaging of possible landing sites for the Phoenix 2007 Mars Scout lander and 2009 Mars Science Laboratory rover; continued mapping and analysis of key sedimentary-rock outcrop sites; and continued monitoring of changes on the surface due to wind and ice. Because the narrow-angle camera has imaged only a small fraction of the surface, new discoveries about surface features are likely to come at any time. The extension runs two years, through September 2006, with a budget of $7.5 million per year.
This animation portrays the movements that NASA's Mars Global Surveyor undergoes to acquire an enhanced-resolution image using a technique called compensated pitch and roll targeted observation. Controllers adjust the rotation rate of the spacecraft to match the ground speed under the camera while the orbiter passes over the target.
Dr. James Garvin, NASA's chief scientist for Mars and the Moon, said, "Mars Global Surveyor continues to catalyze new science as it explores Mars at scales compatible with those that our Mars Exploration Rovers negotiate every day, and its extended mission will continue to set the stage for upcoming observations by the Mars Reconnaissance Orbiter."
Additional information about Mars Global Surveyor is available online at: http://mars.jpl.nasa.gov/mgs/. In addition to semi-annual releases of large collections of archived pictures, the Mars Orbiter Camera team posts a new image daily and last year began soliciting public suggestions for camera targets on Mars. These materials can be viewed online at http://www.msss.com . For more information about NASA and other space science programs on the Internet, visit http://www.nasa.gov.
JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Global Surveyor mission for NASA's Science Mission Directorate, Washington, D.C. JPL's industrial partner is Lockheed Martin Space Systems, Denver, which built and operates the spacecraft.