New resultsfrom NASA's Phoenix Mars lander suggest that the surface layers of the Martianarctic region may not be as friendly to life as initial results suggested, NASAsaid today.
Two samplesanalyzed within the last month by Phoenix's Microscopy, Electrochemistry andConductivity Analyzer (MECA) suggest that the Martian dirt may containperchlorate, a highly oxidizing substance, which would create a harshenvironment for any potentiallife.
Thefindings stand against the results from MECA's first analysis, which indicatedthe dirt was Earth-like in certain respects, including its pH and the presenceof certain minerals.
"InitialMECA analyses suggested Earth-like soil. Further analysis has revealedun-Earthlike aspects of the soil chemistry," said Phoenix principalinvestigator Peter Smith.
The news cametoday on the heels of a report on Friday that MECA had foundintriguing results that had been shared with the White House. Incorrespondence with SPACE.com, Smith denied that any briefing with theWhite House had been held.
And thefindings are inconclusive as yet, Smith indicated. "We are committed tofollowing a rigorous scientific process," he said. "While we have notcompleted our process on these soil samples, we have very interestingintermediate results."
NASA willhold a press briefing tomorrow to further discuss the new MECA findings.
The Phoenix team had been waiting for results from Phoenix's Thermal and Evolved-Gas Analyzer(TEGA) to see if it also detected perchlorate in dirt samples. TEGA's tinyovens heat the samples and then "sniffs" the vapors given off todetermine their composition.
Sunday'sTEGA experiment, which analyzed a sample taken directly above the ice layer,found no evidence of perchlorate.
"Thisis surprising since an earlier TEGA measurement of surface materials wasconsistent with but not conclusive of the presence of perchlorate," Smithsaid.
The team isworking to rule out the possibility that the perchlorate readings could becontamination brought from Earth.
"Whensurprising results are found, we want to review and assure our extensivepre-launch contamination control processes covered this potential," saidBarry Goldstein, Phoenix project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
MECA's wetchemistry laboratory mixes samples of Martian dirt with water brought fromEarth. Sensors on the inner surface of the beakers act like electronic tonguesand "taste" the dirt to detect salts that can dissolve in water. Thesensors can also detect the pH of the surface.
All of thisinformation gives scientists a picture of what the surface layer of dirt lookslike now and whether or not it might have been a habitable area at some pointin the planet's past.
MECA's firstanalysis showed that the Martian regolith contained several solubleminerals necessary for life, including potassium, magnesium and chloride. Thesurface also had an alkaline pH, which on Earth is suitable for growing someplants, such as asparagus.
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