Absence of Mars organic compounds studied

ARGONNE, Ill., June 15 (UPI) -- U.S. scientists have offered a new theory as to why no organic compounds such as proteins have been found in martian soil.

"There may be no 'safe haven' for these organic molecules on Mars," said Ilya Shkrob, Sergey Chemerisov and Timothy Marin, from the Argonne National Laboratory and Benedictine University in Illinois.

Unlike Earth, where plants and other organisms convert carbon dioxide and water into organic compounds via photosynthesis, the researchers posit the opposite occurs on the surface of Mars.

The scientists explain iron oxides in martian soil that give the planet its distinctive red color are photocatalysts. They use energy from ultraviolet light absorbed through Mars' thin atmosphere to oxidize carbon-containing organic molecules trapped in soil particles, converting them to carbon dioxide and gases such as methane.

The researchers say that's why it might not be realistic to rely on the discovery of proteins, amino acids and other carbon-containing compounds in the upper soil layers of Mars to determine whether life forms are or have been present on the planet.

The study appears in the journal Astrobiology and is available at: http://www.liebertonline.com/doi/pdfplus/10.1089/ast.2009.0433.