London, May 2 : European Space Agency's (ESA) ExoMars mission in 2013 will use the Urey instrument to drill down 2 metres into the Martian soil in search for life.
According to a report in New Scientist, if there is life on Mars, it might soon be coaxed out of hiding by the new instrument, which is designed to detect the subtle chemical traces of biological activity.
With one of its aims being scouting for amino acids, the Urey instrument will separate out different chemicals inside a set of fluid-filled channels using a process called electrophoresis.
Chemical signs of life can be ambiguous, but scientists are hoping that Urey will be able to tell whether any amino acids on Mars were made by living organisms or some other process.
The key is to measure the symmetry, or "chirality" of each amino acid, which can be in either of two mirror-image configurations, labelled L and D.
"Life on Earth is based on chiral molecules, so our underlying assumption is that this is a central feature of biochemistry," said instrument team leader Jeffrey Bada of the University of California, San Diego, US.
The lesson from Earth is that biology will use only one of the two possible chiral forms. All amino acids in terrestrial life are of the L form, whereas synthetic amino acids come in equal mixtures of L and D.
The instrument will contain a "lab on a chip", where different chemicals will be separated out inside a set of fluid-filled channels by a process called electrophoresis, which takes advantage of the fact that different ions move at different speeds in an electric field.
According to scientists, Urey should be able to distinguish between the two forms of a given amino acid by the way they react with another chiral molecule, g-cyclodextrin.
As well as being lightweight and having low power consumption - both vital for use in a space mission - this technology is sensitive to very small quantities of a given chemical.
"We're down to the level of being able to detect a few cells per gram," Bada told New Scientist.
The ideal outcome, according to Bada, would be if Urey finds only D-amino acids. That would be compelling evidence of life, and truly alien life, based on a biochemistry that is a mirror image of our own.
"But if we find L acids, then things get more complicated," said Bada.
It could mean that during the emergence of life on Earth and Mars, both happened to choose L acids by chance. "Or it may imply we're related in some way, that microbes from Earth seeded Mars, or vice versa," he said.
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