Phoenix Gets Close-up Look at Mars Dirt
NASA's Phoenix Mars Lander got its first (very) close-up look at Martian soil, scientists said Friday.
"This is the highest resolution image of the soil of Mars," said the mission's geology team leader, Tom Pike of University College London. "This is the first time we've reached down to this level."
The microscope images show a wide variety of particle sizes, colors and types in the soil. One of the particles viewed through the microscope is just 50 microns across, a little less than diameter of human hair. It is greenish in one part, which Pike says could be olivine, a mineral seen elsewhere on Mars. The other part of the particles "the very characteristic orange color" of the Martian soil as a whole, Pike said.
Another particle is black, glassy and more rounded in its shape. "This may very well be a volcanic glass," Pike said.
The microscope images also showed that the clumpy tendencies of the soil go right down to the microscopic level. The green-and-orange particle is actually "a clump of even finer particles," Pike said.
"It's obviously a very sticky material right down to the finest scale," he added.
The tendency of the soil particles to stick together has caused some problems for the mission. When the first soil sample was delivered to the Thermal and Evolved-Gas Analyzer (TEGA) on June 6, it got stuck behind the screened entrance to the instrument. After using a vibrator on the machine, the soil eventually loosened and fell into TEGA. Results from TEGA's first analysis should be sent back to mission scientists next week.
To get around the clumping problem, scientists are now using a "sprinkle" technique to deliver samples. The scoop on the robotic arm is tilted forward, and then a rasp at the end (designed for scraping up hard ice) is run to dribble the soil into the instrument, like a salt shaker. This was the technique used to deliver the sample to the microscope.
The robotic arm continued digging
into its first two trenches, Dodo and Baby Bear, revealing more of the
unidentified white material seen under the surface layer of regolith.
To find out what the material is,
"we need to gather a sample of it and put it in our instruments,"
principal investigator Peter Smith of the
TEGA in particular will be useful: It is extremely sensitive to water, so if the white material is ice, TEGA should sniff it out right away.
The meteorological instruments have
also continued observing the Martian atmosphere. Images of the air above
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