'New technique may help zero in on Martian life'

Washington, Sep 18 MIT scientists have developed a novel spectroscopic technique that may help NASA's new Mars rover, to be launched in 2020, find signs of present or former extraterrestrial life on the red planet.

In 2020, NASA plans to launch a new Mars rover that will be tasked with probing a region of the planet scientists believe could hold remnants of ancient microbial life.

The rover will collect samples of rocks and soil, and store them on the Martian surface; the samples would be returned to Earth sometime in the distant future so that scientists can meticulously analyse the samples for signs of present or former extraterrestrial life.

Now, scientists at Massachusetts Institute of Technology (MIT) in the US have developed a technique that will help the rover quickly and non-invasively identify sediments that are relatively unaltered, and that maintain much of their original composition.

Such "pristine" samples give scientists the best chance for identifying signs of former life, if they exist, as opposed to rocks whose histories have been wiped clean by geological processes such as excessive heating or radiation damage, researchers said.

The team's technique centres on a new way to interpret the results of Raman spectroscopy, a common, non-destructive process that geologists use to identify the chemical composition of ancient rocks.

Among its suite of scientific tools, the 2020 Mars rover includes SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals), an instrument that will acquire Raman spectra from samples on or just below the martian surface.

SHERLOC will be pivotal in determining whether life ever existed on Mars.

Roger Summons, professor at MIT, said the chemical picture that scientists have so far been able to discern using Raman spectroscopy has been "somewhat fuzzy." Nicola Ferralis, a research scientist at MIT, discovered hidden features in Raman spectra that can give a more informed picture of a sample's chemical makeup.

Specifically, the researchers were able to estimate the ratio of hydrogen to carbon atoms from the substructure of the peaks in Raman spectra.

This is important because the more heating any rock has experienced, the more the organic matter becomes altered, specifically through the loss of hydrogen in the form of methane, researchers said.

The improved technique enables scientists to more accurately interpret the meaning of existing Raman spectra, and quickly evaluate the ratio of hydrogen to carbon - thereby identifying the most pristine, ancient samples of rocks for further study.

Summons said this may also help scientists and engineers working with the SHERLOC instrument on the 2020 Mars rover to zero in on ideal Martian samples.

The research was published in the journal Carbon.

PTI