Rare organic molecules on Mars are formed by life rather than anything else

Rare organic molecules on Mars are formed by life rather than anything else
Rare organic molecules on Mars are formed by life rather than anything else
Anonim

A rare species of organic matter may be evidence of the habitability of the Red Planet. If such substances were found in terrestrial samples, they would definitely be considered biogenic, the researchers are sure.

The details are set out in a scientific article published in the journal Astrobiology by Jacob Heinz and Dirk Schulze-Makuch of the Technical University of Berlin.

We are talking about thiophene (C4H4S) and its derivatives. On Earth, these substances are found in crude oil, natural gas, and some mushrooms. They are also present in microfossils and stromatolites.

Not so long ago, these compounds were discovered on Mars. Their origin, however, remains unknown.

"If we found thiophenes on Earth, we would think that they are biogenic. But in the case of Mars, the bar for the necessary evidence, of course, should be somewhat higher," says Schulze-Makuch.

The authors considered several possible routes for the synthesis of these substances.

It is easy to imagine that they were produced by Martian bacteria in those distant times when the Red Planet was wetter than modern Earth. This scenario seems to be the most natural by the expert.

But other options cannot be ruled out either. For example, these compounds could be formed during the fall of meteorites (for the abiogenic synthesis of thiophene, temperatures above 120 degrees Celsius are required).

“We have identified several biological pathways for [synthesizing] thiophenes that seem more likely than chemical ones. But we still need [additional] evidence,” explains Schulze-Makuch.

Researchers are pinning their hopes on the rover Rosalind Franklin, which is due to travel to the Red Planet in 2020 as part of the ExoMars mission. Its equipment uses more gentle analysis methods than Curiosity instruments. The latter decompose large organic molecules, and chemists restore the picture literally from their fragments.

In addition, the equipment of the new rover will make it possible to determine the content of various isotopes of sulfur and carbon in thiophene. On Earth, an unusually large fraction of light isotopes is clear evidence that the substance has been inside a living organism.

However, experts do not exclude that such a result will not be recognized as the final evidence of the existence of life on the Red Planet.

"As Carl Sagan said, extraordinary claims require extraordinary evidence," Schulze-Makuch concludes. …

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