Searching for Life on Mars

In March, scientists at NASA concluded from evidence gathered by the two Mars Rovers, Opportunity and Spirit, that the red planet probably did at one time have deposits of liquid water-suggesting the sustainability of past Martian life.

Meanwhile, UC Berkeley researchers, in conjunction with the Jet Propulsion Laboratory and UC San Diego's Scripps Institution of Oceanography, are working on the next step in the search for past life: the presence of amino acids-the building blocks of proteins-in Martian soil.

"There are two main ingredients that are required for development of life on Mars: water and organic molecules. We have already found evidence of water; now we need to find organic molecules such as amino acids." said Berkeley professor of Chemistry and principle investigator Richard Mathies.

Mathies and his team have already received $2 million in grants from NASA to develop an instrument, dubbed the Mars Organic Analyzer (MOA), which will potentially fit aboard NASA's robotic rover, the Mars Science Laboratory, slated for launch in 2009. In addition the MOA may also be used aboard the European Space Agency's ExoMars Mission, also slated for launch in 2009.

The MOA will incorporate state of the art technology, the same used in sequencing the human genome, to test for the presence and characteristics of amino acids in the soil.

More importantly, provided that amino acids are found in the soil, the MOA will then test for the handedness, or chirality, of the amino acids present. Testing for chirality would indicate whether or not the amino acids were made by past life forms.

All amino acids come in one of two 3-dimensional forms: left handed and right handed. A fundamental characteristic of life on Earth is that amino acids made via life are only left handed.

In space, however, amino acids can be spontaneously made through non-life processes. These non-life processes only produce racemic mixtures; that is, mixtures with equal amounts of left handed and right handed molecules.

"The implications of this device are huge," said Alison Skelley, graduate student on the project, "if we go to Mars and find homochirality, an excess of one form of amino acid over the other, we will have very strong evidence of past or present life on Mars."

The MOA, building off a precursor designed by Jeffrey Bada of Scripps known as the Mars Organic Detector or MOD, would first search for the presence of amino acids and then check for their handedness.

The MOD works by heating a sample of Martian soil to high temperatures, causing the organic material in the soil to vaporize into a tube which then cools the material onto a finger-like substrate. The substrate is coated with a dye that only attaches to amino acids. This then allows for detection of amino acids.

The second step then involves drawing the amino acids into a small tube to detemine what types of amino acids are present.

The Mathies team addition incorporates a glass micro-chip that tests for chirality of the molecules by driving them down a tube that separatesthe left and right handed amino acids.

The amino acids are separated by a molecule in the tube that impedes the movement of left handed molecules. The results will give an idea of the percentage of left and right amino acids.

The MOA, however, still has to undergo considerable engineering and field testing to account for size, weight, and energy consumption restrictions as well variable conditions on Mars.

In February Skelley traveled to the Atamaca Desert in Chile to see if the MOA could detect amino acids in harsh arid regions, similar to what would be expected on Mars.

"We are optimistic that our device will be able to handle whatever Mars throws at us." said Skelley.

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