The variety of organic compounds on Mars amazes scientists – Futura

The variety of organic compounds on Mars amazes scientists – Futura

Not only rovers make it possible to study the geology of the red planet in detail. Martian meteorites are also a source of important data.

Fragments of Mars do indeed periodically fall to Earth. In fact, they are quite numerous. The Tissint meteorite crashed in Morocco’s Tata province on July 18, 2011. Its entry into the atmosphere was also observed in real time and the pieces of the meteorite were finally found by nomads a few months later. The total mass of the Tissint meteorite was estimated at around 7 kilos.

His analysis showed it to be a 582-million-year-old fragment of Martian rock that would have been ripped from the planet in a major impact about 1 million years ago. Studying the Tissint meteorite could therefore make it possible to better understand whether the Red Planet could have hosted life. And one of the elements to consider in this huge problem is the presence of organic molecules.

A meteorite that allows us to better understand the carbon cycle on Mars

Be careful, when we speak of organic molecules we must not think of molecules that are necessarily synthesized by living organisms. These are primarily carbon, hydrogen, oxygen, nitrogen, nitrogen or sulfide-rich molecules which, if they are actually involved in biological reactions, can result from so-called abiotic-abiotic (non-biological) reactions. However, understanding the processes and sequences that produced these organic molecules could shed light on whether Mars ever exhibited favorable conditions for habitability and what reactions might have led to the emergence of life. However, it turns out that the Tissint meteorite has a large variety of organic molecules. By correlating the nature of organic molecules with mineralogy, researchers were able to create a very complete catalog of the Martian diversity of organic compounds and better understand the evolution of the Red Planet’s crust and mantle in conjunction with water-rock interactions.

The Tissint meteorite turned out to be particularly rich in organic molecules containing magnesiummagnesium, molecules previously not observed on Mars, formed by chemical reactions at high pressure and temperature. These molecules show that the mineralogical evolution of the planet’s interior was closely linked to a carbon cycle, as on Earth. The results were published in the journal Science Advances.

A team of Japanese researchers first demonstrated the existence of nitrogenous organic molecules on Mars 4 billion years ago. This is good news for the appearance of life on the red planet at this time.

Article by Laurent SaccoLaurent Sacco published May 4, 2020

Ideally, the search for life on Mars would require all the analytical tools necessary to highlight at least traces of past life on the red planet. This is not possible, and for this reason it would be necessary to be able to bring samples of its soil back to Earth, such as samples obtained in a series of wells planned for NASA’s Mars 2020 mission. The Perseverance rover, which adopts the architecture of the Curiosity rover, will therefore take dozens of core samples from the Martian sediments in locations that are believed to have been favorable for the occurrence or at least the evolution of life forms.

In particular, these sites may belong to the geological period of Mars called the NoachianNoachian (from the name Noachi’s Terra), which corresponds to the oldest land since the planet’s formation, dating back at least 3.5 to 3.7 billion years, when the Red Planet probably still had a dense atmosphere that created a greenhouse effect that allowed the existence of large amounts of liquid liquid water. The Carrots of Perseverance would then await another mission to bring them back to Earth.

A presentation of the men and women behind the Perseverance rover’s mission. For a fairly accurate French translation, click the white rectangle at the bottom right. Then the English subtitles should appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose French. © NASA360

More than 200 Martian meteorites on Earth

However, we already have samples of Martian rock, about 200 meteorites, divided broadly into three broad classes, named for the villages near which people witnessed their fall. Thus in 1815 the case near the French village of Chassigny, that of Shergotty in India (1865) and that of Nakhla in Egypt (1911) were observed.

Often they are igneous rocks formed from the cooling of a magma magma, for example in the form of lava slaves on the surface of Mars, but also in its mantle. The impact of a small celestial body would have been strong enough every time to eject fragments of Mars into space with these boulders, with the planet’s low gravity helping to do this. In some cases, gas bubbles were found in these fragments found on Earth, the composition of which was close to the Martian atmosphere known since the Viking missions, which greatly helped clarify the origin of these meteorites.

One meteorite in particular has been much talked about, Allan Hills (ALH)84001, named for the region of Antarctica where it was discovered in 1984, as Futura recalled in the previous article below. In 1996, NASA researchers believed they had identified fossilized fossils of nanobacteria, which may not be of terrestrial origin or arose from purely Martian geochemical processes, reproducing biological structures without actually being one. They must have been disillusioned, but today Japanese researchers return to the Allan Hills (ALH)84001 case in a paper published in Nature Communications.

Nitrogen-containing organic molecules in carbonates

Allan Hills 84001 is an orthopyroxenite, an igneous rock composed almost entirely of pyroxene pyroxenes that crystallized in the interior of Mars about 4.1 billion years ago, during the Noachian period. It is one of the oldest known Martian meteorites. It contains nodules of carbonates, mostly precipitating in groundwater, which inherently suggests a hot and humid environment early in Martian history, favorable for life.

Organic molecules have been found in these aerated minerals, but the whole question at first was whether these molecules had formed on Mars more than 4 billion years ago or were the result of very recent terrestrial contamination. For the first hypothesis, quite convincing arguments were made more than 10 years ago, as explained by Futura in the previous article below. Wanting to go further, the team of Japanese researchers prepared samples of ALH84001 to be even more certain that there was no contamination, in particular by detecting for the first time nitrogen in the organic molecules present. Remember that nitrogen (N) is an essential part of amino acids, amino acids and also DNADNA and RNARNA, the molecules of life.

Astrochemists in a clean room used a silver tape to tear tiny grains of carbonate, the width of a human hair, from meteorite ALH84001. They then prepared these grains to remove possible surface contamination using a focused ion beam from a scanning electron microscope. A technique of X-ray absorption spectroscopy allowed them to detect nitrogen, which was present in very small amounts and forms.

Since the igneous minerals near the carbonate minerals did not provide any detectable nitrogen, this showed that the nitrogenous organic molecules were only found in the carbonate nodules, which cannot be explained by contamination. The researchers also found no nitrates like those that make the Martian soil very oxidizing and not conducive to surface life, suggesting they didn’t exist in the Noachian, another reason to believe in the habitability of Mars around 4 billion years ago.

On the other hand, it remains difficult to know whether these nitrogenous molecules are the product of abiotic processes, such as comets and meteorites, or, on the contrary, of life forms. In any case, this indicates that the Martian chemistry of the time supported life anyway.

Article by Laurent Sacco, published on 12/13/2007

The world-famous Martian meteorite Allan Hills 84001 is once again making headlines. Without providing any indisputable proof of the presence of life on Mars in the past, this time it proves that the Martian environment allows the synthesis of organic molecules: this is a first!

We remember NASA’s overwhelming announcement of August 6, 1996 of evidence of past life on Mars. By analyzing Martian meteorite ALH84001, an achondrite discovered in December 1984 in Antarctica in the Allan Hills region, hence its name, NASA researchers believed they had indeed uncovered fossils of nanobacteria not native to Earth or biological structures could reproduce themselves through purely geochemical processes without really being such.

Things have clouded over fairly quickly in recent years, and these tracks are no longer considered solid evidence that life appeared on Mars billions of years ago. However, scientists at the Carnegie Institution’s Geophysics Laboratory now believe they used the same meteorite to prove that at least some of life’s basic carbon molecules were actually synthesized by the Red Planet.

The message from the land of the armored bears

The discovery comes from comparing this piece of Marslava, crystallized 4.5 billion years ago, with samples of terrestrial lava from Svalbard, the region also called SpitzbergSpitzberg and therefore not a simple invention of Philip Pullman’s novels now known as “At the Crossroads.” of the Worlds” were brought to the screen.

The Svalbard lava studied by the team erupted in the Arctic Ocean about a million years ago. The cold climate approximates Martian conditions. However, within these lavas there are small spheres of aerated minerals containing organic molecules closely associated with a fairly famous iron oxide in the form of a mineral mineral called magnetite magnetite. During a volcanic eruption, magnetite acted as a catalyst in contact with fluids rich in carbon dioxide, carbon dioxide and water, although life was not possible at the time due to the temperature. Small spheres of this type were found in ALH84001 and are therefore most likely molecules synthesized by Martian chemistry and not by later terrestrial contamination. This is the first time evidence of this type has been presented, and it reinforces the belief that organic molecules must easily surface on the surfaces of large telluric planets in the Universe, even when it’s cold there! Launched in 2009 to support Spirit and Opportunity, Opportunity, if they’re still active, will no doubt tell us more.