NASA Eyes Lifeless Mars

The latest images from NASA's Mars Global Surveyor portray a climatically diverse yet lifeless planet -- a place where a mountain soars 17 miles high and a canyon plunges 11 miles deep.

More than 350 researchers gathered in Pasadena on Monday at a conference to discuss the findings of Surveyor, which began mapping the planet in March and will do so for 687 days, a full Martian year.

The Surveyor mission has yet to produce any evidence that life could ever exist on Mars. An instrument that studies the composition of surface minerals has so far found no rocks from which the building blocks of life could develop, said Arden Albee, Surveyor's project scientist and organizer of the Fifth International Conference on Mars.

"Things that we thought would be the precursors of life have not shown up," he said.

But four months into the mission, scientists say they have acquired the most accurate picture of any planet in the solar system.

"We know the topography of Mars better than we know the topography of Earth," Albee said.

The $250-million spacecraft already has found that Mars is shaped like a pear; its mountainous southern half is nearly two miles higher than its flat northern hemisphere. Its surface has the highest, lowest and smoothest landforms found in the solar system.

"We are seeing a very interesting planet in that we have no idea of how it got into that form," said David Smith of NASA's Goddard Space Flight Center in Greenbelt, Md. Smith is the principal investigator for the instrument that measures the planet's elevations.

Smith's instrument, known as a laser altimeter, has never been used to systematically measure all of Earth's continents, although such a mission is planned for the future.

The Surveyor altimeter will re-scan the same areas to find out how those regions have changed. Researchers hope to learn more about how the planet's ice caps grow as well as its weather patterns.

A landing site for the next Mars probe, which arrives in December, will be determined over the next few months using Surveyor data.