June 6, 2008

Phoenix Returns High-Res Pictures of Dust and Sand

NASA scientists said on Thursday that the Phoenix lander, in its search for signs of life on Mars, has returned the highest-resolution pictures ever taken of dust and sand on the surface of another planet.

The $420-million craft touched down May 25 on the arctic circle of Mars after a 10-month, 420-million-mile (680-million-km) journey from Earth.

An optical microscope took the pictures, revealing particles"”some as small as one-tenth the diameter of a human hair"”that were collected on a slide after the lander kicked up dust from the surface.

"We have images showing the diversity of mineralogy on Mars at a scale that is unprecedented in planetary exploration," said Michael Hecht of the U.S. space agency's Jet Propulsion Laboratory.

The Scientists hope to find ice, which is considered key to enabling life on the planet. One of the tiny grains shown in the pictures, taken largely to test the lander's instruments, was clear and whitish but the scientists said it was a mineral"”possibly salt"”and not likely ice.

Other particles were reddish brown like the Mars surface or dark and glossy.

"What we're seeing in the microscope is almost certainly not ice because a particle of ice that small would have melted before it could be photographed," said Tom Pike, Phoenix geology team leader and a professor at Imperial College London.

He said the Phoenix team would be intrigued if they were salt deposits, which are often found around ice.

"The microscopic photos were never intended to seek out ice or other signs of water and life on Mars, and that the primary tool for that is a robotic arm," said Pike.

A communication glitch with an orbiting spacecraft delayed the lander's first experiment, collecting a soil sample from the Martian surface.

NASA officials are eager to study the samples obtain from initial tests by the robotic arm scoop that uncovered a layer 1.5 inches deep near the landing site.

The robotic camera on the Phoenix has also sent back images of what appears to be exposed ice under the lander. But that area"”dubbed "Snow Queen""”cannot be analyzed because it is out of the reach of the scoop.

In the past decade, NASA has used a fleet of orbiters and a pair of rovers to search Mars for signs of water and conditions that might have supported life.

In 2002, the Odyssey spacecraft detected subsurface water on Mars, prompting further exploration with the Phoenix mission.


Image Credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University


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