The Mars Reconnaissance Orbiter on Friday returned the first test images from its super high-resolution cameras, the most powerful photographic equipment to be trained on the Red Planet in NASA's search for water and life.

　　The black-and-white photos, taken by three cameras, show deep channels and layered surface debris around the planet's midsection, features that probably were formed by water, said Alfred McEwen, a mission scientist and University of Arizona professor of planetary science.

　　The images were taken from an altitude of 1,547 miles above the surface, about three times higher than the orbiter will be when it formally begins its science mission in November.

　　The spacecraft, which reached orbit on March 10, is to map about 1 percent of the Martian surface for future landings by robotic probes and human astronauts.

　　The resolution of the test images is comparable to those captured by the less powerful cameras of three other orbiters circling Mars, but the tests show that cameras survived the seven-month space trip that began in August.

　　NASA scientists will use the images to calibrate the cameras, and will later combine the images to create broader view and to add color. They are available for viewing at www.jpl.nasa.gov.

　　Over the next seven months, the orbiter will "aerobrake," dipping into Mars' atmosphere and gradually changing its elliptical orbit into a near-circle about 185 miles above the planet's surface. In the lower orbit, scientists will be able to distinguish surface objects as small as 3 feet (1 meter) wide, McEwen said.

　　The Mars Reconnaissance Orbiter has a suite of onboard instruments to map the planet's subsurface minerals, monitor its atmosphere and look for evidence of subsurface ice or water.

　　"At this point we have an idea that water is probably abundant on Mars in the form of ice," McEwen said. "It's not a matter of finding water on Mars but learning its importance in climate change ... and clearly it has been important to shaping the landscape."

　　The orbiter's first mission is to find landing sites for the Phoenix Mars Lander, set to arrive on Mars in May 2008 to dig for subsurface water ice, and for the 2009 arrival of the Mars Science Laboratory, a larger version of the twin robotic geologists Spirit and Opportunity, which have been traversing the planet's surface since 2004.