We need to dig deeper to find traces of life on Mars, NASA experiment showed

(ORDO NEWS) — Martian rovers need to take soil samples from depths of about two meters or more to detect signs of ancient life, according to a new NASA lab experiment, because ionizing radiation from space degrades small molecules, such as amino acids, relatively quickly.

“Our results show that amino acids are being degraded by cosmic rays in rocks and regolith on the surface of Mars at a much higher rate than previously thought,” said Alexander Pavlov of NASA’s Goddard Space Flight Center, USA.

“Modern all-terrain missions penetrate the soil for sampling to a depth of only about five centimeters. At these depths, the complete destruction of amino acids takes only 20 million years. The addition of perchlorates and water further increases the rate of degradation of amino acids.”

A period of 20 million years is a relatively short period of time, as scientists are looking for traces of the presence on the surface of ancient life that could have inhabited the Red Planet for billions of years at a time when Mars was more like our Earth.

These results necessitate a new strategy for missions whose sampling capabilities are limited to shallow depths only.

“In the case of missions limited to sampling from shallow depths, one should look for fresh outcrops of deep strata to the surface that is, recent microcraters that are less than 10 million years old, or material erupted from such craters,” said Pavlov, who is the chief the author of a new study.

In their work, Pavlov’s team mixed several types of amino acids with samples of silica, hydrated silica, and perchlorate to replicate Martian soil conditions, and then sealed the samples in laboratory test tubes to mimic the rarefied Martian atmosphere.

Some samples were kept at room temperature, while other samples were cooled to minus 55 degrees Celsius, a temperature more typical of Mars. In addition, the samples were exposed to different levels of gamma radiation to simulate exposure to cosmic rays.

This experiment differs from previous similar experiments in that, for the first time, the effect of radiation was produced not on isolated organic molecules, but on organic molecules mixed with imitation of Martian soil.

As it turned out, silica and perchlorate additives significantly reduce the resistance of organic molecules to destruction under the action of ionizing radiation.


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