New Instrument to Probe Mars Surface for Signs of Life with Unprecedented Precision

Future missions to Mars will carry instruments designed to detect biological signals with unprecedented sophistication and the potential to determine once and for all whether life exists or has existed on the Red Planet.

An instrument developed by a scientist at Scripps Institution of Oceanography at UC San Diego, along with his colleagues at the Jet Propulsion Laboratory in Pasadena, UC Berkeley, NASA's Ames Research Center in Menlo Park and the Leiden Institute of Chemistry in the Netherlands, is designed to provide the most rigorous analysis possible for the past and present biotic potential of Mars' surface.

Scripps Oceanography Professor Jeffrey Bada will discuss details of the "Urey Mars Organic and Oxidant Detector" during the 2006 American Geophysical Union Fall Meeting (Friday, Dec. 15, at 1:40 p.m. in Moscone West Room 3024).

"Urey will be the most aggressive attempt yet to find out whether there is any evidence that life ever existed on Mars," said Bada. "If we discover convincing evidence for life on Mars, it will be the first demonstration that life may be ubiquitous in the universe wherever the conditions are favorable. This is a once-in-a-lifetime opportunity to carry out a cutting-edge investigation of whether life exists beyond Earth."

The Urey instrument, named after the late Nobel Laureate and UC San Diego scholar Harold Clayton Urey, will perform the first in-situ search for key classes of organic molecules in the Martian environment using state-of-the-art analytical methods at part-per-trillion sensitivities.

"Urey will able to detect key molecules associated with life at a sensitivity roughly a million times greater than previous instrumentation," said Bada, a professor of marine chemistry and director of the NASA Specialized Center of Research and Training in Exobiology at Scripps. "It will be the first instrument to have the capacity to detect amino acids, along with other possible biomolecules, and determine their origin on another planet."

Urey has been selected for the "Pasteur" payload of the European Space Agency's ExoMars rover mission, a Mars exploration mission scheduled for launch in 2011 that will focus on exobiology, the science of life in space and on other planets. ExoMars will include a highly mobile rover with a drill capable of extracting soil samples two meters below the Mars surface.

A compact instrument that you can hold in your 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 finger," a trap cooled to Mars' night time temperature, and then probed with a laser.

If amino acids are detected, the instrument examines the chirality, or "handedness," of the molecules to determine whether they come from biological sources. Non-biological amino acids contain nearly equal amounts of left- and right-handed forms, while those from organic matter exhibit excessive amounts of one hand or the other. Amino acids on Earth use only left-handed amino acids.

"Testing for chirality provides an unambiguous way of detecting life," said Bada. "So if we see a significant excess of right-handed amino acids, the only conclusion that's possible is: Eureka! We've detected unique Martian life that's not related to Earth life whatsoever."

Bada indicated that digging deep into the Martian soil is vital to the mission since ultraviolet and cosmic radiation have likely eliminated any potential indications of life on the planet's surface.

"Humans are incredibly intrigued about the possibility of life beyond Earth," said Bada. "We're at a moment in time when we are going to be addressing this issue in the most robust way that's ever been attempted. I think it is extraordinarily interesting that if we do detect life on Mars, it not only provides us with an opportunity to try and understand how life began on that planet, but also will help us understand how life began on our own planet."