[meteorite-list] Phoenix Analyzing Martian Soil Data

[Ron Baalke]

Aug. 4, 2008

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown at nasa.gov

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov

Sara Hammond
University of Arizona, Tucson
520-626-1974
shammond at lpl.arizona.edu

RELEASE: 08-199

NASA SPACECRAFT ANALYZING MARTIAN SOIL DATA

WASHINGTON -- Scientists are analyzing results from soil samples 
delivered several weeks ago to science instruments on NASA's Phoenix 
Mars Lander to understand the landing site's soil chemistry and 
mineralogy.

Within the last month, two samples have been analyzed by the Wet 
Chemistry Lab of the spacecraft's Microscopy, Electrochemistry, and 
Conductivity Analyzer, or MECA, suggesting one of the soil 
constituents may be perchlorate, a highly oxidizing substance. The 
Phoenix team has been waiting for complementary results from the 
Thermal and Evolved-Gas Analyzer, or TEGA, which also is capable of 
detecting perchlorate. TEGA is a series of ovens and analyzers that 
"sniff" vapors released from substances in a sample.

NASA will hold a media teleconference on Tuesday, Aug. 5, at 2 p.m. 
EDT, to discuss these recent science activities. Participants will be 
introduced at the start of the briefing. To participate in the 
teleconference, reporters should contact Steve Cole on 202-358-0918 
for dial-in and passcode information.

Confirmation of the presence of perchlorate and supporting data is 
important prior to scientific peer review and subsequent public 
announcements. The results from Sunday's TEGA experiment, which 
analyzed a sample taken directly above the ice layer, found no 
evidence of this compound.

"This is surprising since an earlier TEGA measurement of surface 
materials was consistent with but not conclusive of the presence of 
perchlorate," said Peter Smith, Phoenix's principal investigator at 
the University of Arizona, Tucson.

Scientists at the Phoenix Science Operations Center at the University 
of Arizona, Tucson, are specifically looking at the data from these 
instruments to provide information on the composition of Martian 
soil.

"We are committed to following a rigorous scientific process. While we 
have not completed our process on these soil samples, we have very 
interesting intermediate results," said Smith, "Initial MECA analyses 
suggested Earth-like soil. Further analysis has revealed un-Earthlike 
aspects of the soil chemistry." 

The team also is working to totally exonerate any possibility of the 
perchlorate readings being influenced by terrestrial sources which 
may have migrated from the spacecraft, either into samples or into 
the instrumentation. 

"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.

Since landing on May 25, Phoenix has been studying Martian soil with 
MECA's wet chemistry lab, two microscopes and a conductivity probe, 
TEGA's ovens and two cameras. 

MECA's robotic wet chemistry lab studies soluble chemicals in the soil 
by mixing a soil sample with a water-based solution with several 
reagents brought from Earth. The inner surface of each cell's beaker 
has 26 sensors that give information about the acidity or alkalinity 
and concentrations of elements such as chloride or perchlorate. The 
beaker also can detect concentrations of magnesium, calcium and 
potassium, which form salts that are soluble in water. 

With continuing results and the spacecraft in good condition, the 
mission has been extended through Sept. 30. The original prime 
mission of three months ends in late August. The mission extension 
adds five weeks to the 90 days of the prime mission.

The Phoenix mission is led by Smith at the University of Arizona with 
project management at NASA's Jet Propulsion Laboratory in Pasadena, 
Calif., and development partnership at Lockheed Martin in Denver. 
International contributions come from the Canadian Space Agency; the 
University of Neuchatel, Switzerland; the universities of Copenhagen 
and Aarhus in Denmark; the Max Planck Institute in Germany; and the 
Finnish Meteorological Institute. For information about Phoenix, 
visit: 

http://www.nasa.gov/phoenix

	
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