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Martian soil too oxidizing for life |
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Written by Derek Kessler on
Wednesday, 20 August 2008
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 With the samples that NASA’s Phoenix Mars Lander has collected in the Martian arctic, we have been able to confirm the presence of water on Mars. However, the probe’s Microscopy, Electrochemistry and Conductivity Analyzer (MECA) is now indicating that the soil contains perchlorate, a highly oxidizing substance that would make for a harsh environment for plant life. Apart from the perchlorate, the soil is quite Earth-like in pH and mineral composition.
The MECA is a wet chemistry lab, where samples of the Martian soil are mixed with purified water brought from Earth. The small laboratories then analyze the electric conductivity of the mix to detect any salts that may be dissolved. The sensors are also capable of determining the pH (acidity or alkalinity) of the soil.
The Thermal and Evolved Gas Analyzer (TEGA) did not detect any conclusive signs of perchlorate in the samples that it baked. The TEGA superheats a sample of soil and then “sniffs” the vapors given off to determine the chemical composition. There have been indications that the samples might have contained perchlorate, but the readings have been incomplete, and thus inconclusive.
Mars’s soil has been found to be strongly alkaline and contains many soluble minerals considered necessary for life, including potassium, magnesium, and chloride. This chemistry, excluding the perchlorate, would make Martian soil suitable for the cultivation of some Earth plants, like asparagus. Of course, some liquid water would also be helpful.
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