New results
from NASA's Phoenix Mars lander suggest that the surface layers of the Martian
arctic region may not be as friendly to life as initial results suggested, NASA
said today.
Two samples
analyzed within the last month by Phoenix's Microscopy, Electrochemistry and
Conductivity Analyzer (MECA) suggest that the Martian dirt may contain
perchlorate, a highly oxidizing substance, which would create a harsh
environment for any potential
life.
The
findings stand against the results from MECA's first analysis, which indicated
the dirt was Earth-like in certain respects, including its pH and the presence
of certain minerals.
"Initial
MECA analyses suggested Earth-like soil. Further analysis has revealed
un-Earthlike aspects of the soil chemistry," said Phoenix principal
investigator Peter Smith.
The news came
today on the heels of a report on Friday that MECA had found
intriguing results that had been shared with the White House. In
correspondence with SPACE.com, Smith denied that any briefing with the
White House had been held.
And the
findings are inconclusive as yet, Smith indicated. "We are committed to
following a rigorous scientific process," he said. "While we have not
completed our process on these soil samples, we have very interesting
intermediate results."
NASA will
hold 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 tiny
ovens heat the samples and then "sniffs" the vapors given off to
determine their composition.
Sunday's
TEGA experiment, which analyzed a sample taken directly above the ice layer,
found no evidence of perchlorate.
"This
is surprising since an earlier TEGA measurement of surface materials was
consistent with but not conclusive of the presence of perchlorate," Smith
said.
The team is
working to rule out the possibility that the perchlorate readings could be
contamination brought from Earth.
"When
surprising results are found, we want to review and assure our extensive
pre-launch contamination control processes covered this potential," said
Barry Goldstein, Phoenix project manager at NASA's Jet Propulsion Laboratory in
Pasadena, Calif.
MECA's wet
chemistry laboratory mixes samples of Martian dirt with water brought from
Earth. Sensors on the inner surface of the beakers act like electronic tongues
and "taste" the dirt to detect salts that can dissolve in water. The
sensors can also detect the pH of the surface.
All of this
information gives scientists a picture of what the surface layer of dirt looks
like now and whether or not it might have been a habitable area at some point
in the planet's past.
MECA's first
analysis showed that the Martian regolith contained several soluble
minerals necessary for life, including potassium, magnesium and chloride. The
surface also had an alkaline pH, which on Earth is suitable for growing some
plants, such as asparagus.
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