August 5, 2008

Phoenix Lander Detected Harmful Substance In Martian Soil

NASA's Phoenix Lander may have discovered the presence of perchlorate, a chemically reactive salt, in soil samples taken from the surface of Mars, NASA scientists said on Monday.

If the finding is confirmed, it could add doubt to the theory of conditions on the planet being able to sustain life.

The space agency will be working to determine whether the perchlorate came from the Martian soil or the spacecraft. Perchlorate is an oxidizing substance used in rocket fuel. It is known to be harmful to humans under certain circumstances. It is also found in fireworks, pyrotechnics and other explosives.

On Earth, perchlorate is a natural and manmade contaminant sometimes found in soil and groundwater, but scientists are unable to explain how perchlorate forms on Mars or how much there is of it. NASA is investigating whether the substance could have gotten there by contamination before launch. Phoenix used another fuel, hydrazine, to power its thrusters and land on the red planet on May 25.

Previous tests performed by Phoenix showed "Earth-like soil. Further analysis has revealed un-Earthlike aspects of the soil chemistry," chief scientist Peter Smith of the University of Arizona in Tucson said in a statement Monday.

Phoenix detected the salt through a chemistry experiment. The lander mixed soil with water brought from Earth into a teacup-size beaker and stirred it. Two dozen sensors inside the beaker detect the soil's pH and probe for traces of mineral nutrients.

"This is surprising since an earlier (Thermal and Evolved Gas Analyzer) measurement of surface materials was consistent with but not conclusive of the presence of perchlorate," Phoenix chief investigator Peter Smith said.

"While we have not completed our process on these soil samples we have very interesting intermediate results," he said.

In trying to rule out the possibility that perchlorate could have been brought to Mars by Phoenix, NASA was reviewing its pre-launch contamination control processes.

The agency also extended the mission by five weeks, saying its work was moving beyond the search for water to exploring whether the planet was ever capable of sustaining life.

The extension will add about $2 million to the $420 million cost of landing Phoenix on May 25 for what was a scheduled three-month mission.


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