Scientists have a new idea of ​​Mars' mystery of methane and its implications for life

For centuries, scientists have speculated about the existence of life on Mars. But it is only in the past 15 years that the search for life (past and present) has really begun to heat up.

It is at this time that methane, an organic molecule associated with many forms of life on Earth (ie a "biosignature") was detected in the atmosphere of Mars .

Since then, attempts to study atmospheric methane from Mars have yielded varying results. In some cases, methane was found to be several times higher than normal; in others, he was absent.

In an attempt to answer this mystery, an interdisciplinary team from Aarhus University recently conducted a study in which she investigated a possible mechanism for removing methane from the Mars atmosphere.

On March, methane production appears to be seasonal in nature, fluctuating from about 0.24 ppb in the northern hemisphere in winter to about 0.65 ppb in summer.

At the same time, extensive plumes were detected, which shows that it is also periodically released from discrete regions. Twice, the Curiosity rover was near plumes; in December 2014 and again in June.

Different mechanisms have been proposed for the production and disappearance of this methane over the years. In terms of production, they range from non-biological processes such as serpentinization (interactions between water, carbon dioxide and olivine rock) to biological production by microbes.

As for the way it is removed, it also remains a mystery, but more so.

(NASA)

The most obvious mechanism is photochemical degradation, where the Sun's UV radiation causes the decomposition of methane to carbon dioxide, formaldehyde and methanol. However, this process can not explain how atmospheric methane disappears so quickly, which is the most important part of the process.

As part of their study, recently published in the scientific journal Icarus, the Mars Simulation Lab research team of the University of Aarhus proposed that "saltation" be the cause. They essentially argue that wind erosion could be responsible for the ionization of methane into compounds such as methyl (CH3), methylene (CH2) and carbyne (CH).

With the aid of Mars-like minerals, such as basalt and plagioclase, the team discovered that these solids could be oxidized and ionized gases during the erosion process, thus showing that ionized methane reacts and binds to mineral surfaces. They also discovered that silicon atoms in plagioclase (a major component of the Mars surface material) bind to the carbon atoms present in the methyl group derived from methane.

Simulation of wind erosion on Mars. (Mars / AU simulation laboratory)

Based on these findings, the team concluded that this mechanism is much more efficient than the photochemical process and could explain how methane is removed from the Martian atmosphere and deposited in its soil within the observed time frame. But what is perhaps most interesting is the implications of these discoveries on the possible existence of Martian life.

In addition to its effects on methane, the study also showed that these researches on minerals can lead to the formation of oxygen – reactive chemicals such as peroxides, superoxides, and carbon monoxide. other chemicals that are very toxic to organisms, including bacteria. The presence of these compounds essentially means that there is little chance that life can exist on the Martian surface or nearby.

In the future, the team plans to conduct follow-up studies to examine what is happening with bound methane, the more complex organic matter that may come from Mars or have been deposited by meteorites . In short, they want to see if the same erosion process could be responsible for altering or removing this material as atmospheric methane.

We hope that the results of these surveys will shed additional light on a key issue related to the search for life on Mars, namely how organic materials are preserved in the Martian environment. They will also inform future Mars missions looking for clues to life, such as ESA's ExoMars 2020 rover and NASA's March 2020 rover (both of which are expected to arrive in 2021).

This article was originally published by Universe Today. Read the original article.