NASA Mars orbiter to search for lost probes

Cameras need good light to take good pictures and that is why NASA's super-powerful Mars Reconnaissance Orbiter is waiting for a better angle and clear air to begin a photographic search for two Mars probes that disappeared, but are not forgotten.

MRO is presently circling the planet and its cameras are being used to determine if life was ever present on Mars and to characterize its climate and geology to prepare for future expeditionary crew landings. But another MRO mission is locating the crash sites of NASA's Mars Polar Lander and the British-built Beagle 2.

MRO is outfitted with an array of equipment, including the High Resolution Imaging Science Experiment (HiRISE) camera -- built to provide the most detailed view of MarsЎЇ surface to date. From Mars orbit, MRO can take zoom-in images of objects on the surface of the planet, checking out features that are about the size of a small dining room table.

"We'll search for Mars Polar Lander when the lighting conditions are good. Right now it's too dark down there," said Alfred McEwen, Director of the Planetary Image Research Lab at the University of Arizona in Tucson, Arizona. McEwen is MRO's HiRISE principal investigator.

"It's a matter of both illumination angle and atmospheric conditions," McEwen replied when asked to pinpoint a date.

NASA's Mars Polar Lander was launched in January of 1999 and contact was lost on December 3 that same year as the probe neared its south pole exploration target. What happened to the craft and its exact whereabouts is anyone's best guess.

The most probable cause of the failure was due to the generation of bogus signals when the craft's legs were deployed high above the martian landscape, according to a NASA investigation. Those misleading signals are thought to have produced a false indication that the spacecraft's outstretched legs had actually reached Mars.

That misread of its true altitude may have resulted in Mars Polar Lander prematurely shutting down its set of descent engines. Then, it is thought, the craft fell to an ugly ending within MarsЎЇsouth pole region.

The Mars Polar Lander site is on the edge of polar night right now, as Mars is not quite halfway through its southern winter, explained Richard Zurek, MRO's project scientist at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

Zurek said that even when spring comes again to the southern hemisphere on Mars -- February 8, 2007 -- the seasonal snows made largely of carbon dioxide ice will still cover the high southern latitudes. These won't be gone from the area until the latter part of May of next year, he added.

"Right now, MRO is focusing on the high northern latitudes, providing information for the Phoenix mission to use in selecting their landing site," said Zurek.

That will be the main focus for MRO until the end of the calendar year, he said, as Mars moves into late northern winter and observing conditions deteriorate over the north polar area.

NASA's Phoenix lander is to be launched next year, the first in a series of Scout-class spacecraft. It is also a resurrected Mars Polar Lander mission but this time headed for MarsЎЇwater-ice-rich northern polar region.

Early next year the focus will shift to looking at Mars Science Laboratory (MSL) candidate sites, Zurek pointed out. MSL is a hefty wheeled rover to be dispatched to the red planet in 2009.

Source:Xinhua/Agencies