The Phoenix Mars Lander may have detected perchlorate, a potentially toxic substance used in rocket fuel, in soil samples taken from the Red Planet, NASA scientists said on Monday.
The space agency said further tests were required to confirm the presence of perchlorate in Martian dirt and rule out contamination from the spacecraft.
Phoenix is the latest NASA probe to discover whether water, a crucial ingredient for life, ever flowed on Mars and if life, even in the form of microbes, exists or ever existed there.
Last week, NASA said Phoenix had provided definitive proof that water exists on Mars after further tests on ice found by the lander in June.
A NASA spokeswoman declined to characterize perchlorate as detrimental to life.
But perchlorate, an oxidizing substance, is known to be harmful to humans under certain circumstances and its existence in the soil could suggest that Mars is less hospitable to life than the scientists have so far believed.
"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.
He said an initial analysis suggested soil similar to that on Earth but further examinations had revealed "un-Earthlike aspects of the soil chemistry."
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.
Phoenix touched down in May on an ice sheet and samples of the ice were seen melting in photographs taken by the lander's instruments in June.
Mission scientists said then that Martian soil was more alkaline than expected and had traces of magnesium, sodium, potassium and other elements. They described the findings as a "huge step forward."
Last Mod: 05 Ağustos 2008, 14:34