Washington, June 24 : A team of scientists from the US and the UK has developed a technique using ultraviolet light to identify organic matter in soils that could be used to find life on Mars.
Chemical compounds called polycyclic aromatic hydrocarbons (PAHs), often are found on comets, meteorites and in space between the stars, and are considered candidates for being one of the earliest forms of organic matter in the universe.
Like living organisms, these molecules fluoresce when excited by ultraviolet light, making them an ideal target for using this new technology, according to Martin Fisk, a professor of marine geology at Oregon State University and a co-author of the study.Since PAHs are found on meteorites, we would expect some of that material to fall from space onto the surface of Mars," said Fisk.
Computer simulations, including those carried out (by co-authors at) University College London, suggest that the organic material is protected under the surface of Mars, down below a meter or so, and can be brought up via a drill and identified.
In their experiment, the scientists created a fine, dusty soil by crushing a peridotite rock from a nickel mine in Riddle, Oregon, that they say closely replicates the Martian surface material.
A meteorite found in France, originating from Mars, consisted of 88 percent olivine, while the Oregon peridotite was 90 percent olivine.
They infused the peridotite granules with PAHs at a level of 50 parts per million, which is what they would expect to find on a meteorite, then took about a tablespoon of the soil and exposed it to different light waves from a meter away.
Using colored filters from the panoramic camera, or PanCam, that was the backup instrument for the Beagle 2-Lander, they were able to clearly identify as little as 1.5 micrograms of the organic material and pinpoint different PAHs by variations in their fluorescent response.
As part of their tests, the scientists set up a rig that could work under different conditions not dissimilar from the final system that would be mounted on a Mars lander or rover.
According to Jan-Peter Muller, a co-author on the study and a professor of imaging at the University College London's Mullard Laboratory, "Being able to test the fluorescence signature both under laboratory conditions and in the field has been critical to being confident that such a system will work on the surface of Mars."
"The addition of an ultraviolet triage system to search for hints of organic material fits well into the extensive suite of organic detection instruments planned for the MSL and ExoMars expedition," said Michael Storrie-Lombardi, lead author of the study.