Probing Mars for Life

New life-probing instrument reaches next critical step to prepare for mission to Mars

Is there life on Mars? How would it compare to that on Earth? These questions and many others are closer to being answered as a new state-of-the-art instrument developed by a scientist at Scripps Institution of Oceanography at UC San Diego prepares for a mission to the Red Planet in 2013.

The Urey Instrument, developed by Scripps professor of marine chemistry Jeffrey Bada, received $2 million in NASA funding this month to further refine the design, technology for its eventual construction for the European Space Agency's ExoMars mission in 2013.

Named after the late Nobel Laureate and UC San Diego scholar Harold C. Urey, the Urey Mars Organic and Oxidant Detector will perform the first search for key classes of organic molecules in the Martian environment using state-of-the-art analytical methods at part-per-trillion sensitivities.

"If what we understand now about early Mars is correct, then there are compelling reasons to think that life may have begun there just like it did on Earth," said Bada.

Early Mars was believed to be wet with temperatures above the freezing point of water. Whether life could survive the cold and dry planetary conditions that exist today is not yet known. Scientists know that life is based on carbon and requires water, yet the basic organic carbon-containing components of life can be difficult to identify, here and on other planets.

To prepare for a life-detecting mission to Mars, Bada and his research team studied remote isolated regions on Earth, such as Antarctica and the Atacama Desert in Chile. Similar to the Mars environment, the chemical signal associated with life is very hard to detect in these remote regions on Earth because it is present at such low levels.

Landers in NASA's 1970s program Viking tested for organic molecules on Mars, but their sensitivity was inadequate to detect life even if there were a million bacteria per gram of soil.

"You need state-of-the-art analytical methods to detect life in remote areas on Earth," said Bada. "Designing this type of instrument to search for life on another planet is extremely challenging."

The next critical steps is to further refine this highly sensitive technology from operation on a remote desert of Chile to a spacecraft that can be launched, landed and will operate in the harsh Martian environment. For example, the instruments in Bada's lab used to analyze Atacama samples for amino acids, which are an integral component of life, weigh about 25 kilograms (60 pounds). The Urey instrument by comparison weighs only 4 kilograms (9 pounds). According to Bada, the Urey is even more capable of detecting low-level signals of life than the lab instruments and is lightweight to fit within the ExoMars payload.

A compact instrument that can be held in the palm of one's hand, Urey will search for trace levels of organic molecules, such as amino acids and some of the components of DNA and RNA, by heating and analyzing spoon-sized amounts of Martian soil. The molecules released from the heating are condensed on a cold trap. A lab on a chip laser-based device developed by team members at UC Berkeley will probe the trap's contents.

In addition to these organic compound analyses, another Urey component will also test the Martian samples for their ability to degrade organic compounds. The Mars Oxidant Instrument developed by team members at NASA Ames Research Center and the Jet Propulsion Laboratory will enable the scientists to evaluate the stability of compounds directly under Martian conditions. Even if no organic compounds are detected, this stability information will provide important data for understanding the reasons why organic compounds might not be preserved on Mars.

—Annie Reisewitz

May 2008

May 2008