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On the left is a fragment of the Allan Hills Martian meteorite. On the right is an enlarged image of carbonate mineral grains in which organic matter containing nitrogen was found.
Mizuho Koike et al. / Nature Communications
In the Allan Hills 84001 Martian meteorite, found in 1984 in Antarctica, Japanese planetologists were able to detect ancient organic nitrogen-containing molecules. This means that in early Mars there was organic matter carried by meteorites or formed directly on the planet. Article published in Nature’s Communications.
The question of the existence of life on Mars has been studied in detail for many decades. The presence of organic substances in Martian rocks was confirmed by studies carried out by automatic stations on the planet’s surface and the analysis of meteorites of Martian origin found on Earth. Chloromethane on Mars was discovered by Viking missions, and NASA’s Curiosity rover found sulfur and chlorine-containing hydrocarbons in sedimentary rocks of the 3.5 billion-year-old Gale crater. And in the 84001 Allan Hills meteorite, a sample of igneous rock from the Noah period, scientists discovered organic compounds. However, little is known about the origin, distribution, conservation, and evolution of these organic substances, as well as their possible relationship with biological activity on Mars.
So far, they have not tried to find nitrogen compounds in Martian meteorites. Their search was not carried out due to technical difficulties: it was believed that it was impossible to achieve the necessary purity of the experiment, since meteorites are inevitably contaminated with organic matter of terrestrial origin. This problem is even characteristic of Allan Hills 84001, which until its discovery spent many years on Antarctic ice.
Mizuho Koike of the JAXA Institute for Space and Astronautics and his colleagues developed a new method of analysis that allowed me to find nitrogen-containing compounds in a meteorite. Allan Hills 84001 contains orange-colored fine-grained carbonate mineral formations that precipitated into near-surface Martian waters approximately 3.9-4.04 billion years ago. Using a silver double-sided adhesive tape, the scientists extracted several grains of such minerals approximately 50 microns in size and irradiated the samples with X-rays, analyzing them using XANES spectroscopy of the structure near the threshold of the X-ray absorption spectrum, which helps determine substances by measuring the energy with which they absorb radiation. To exclude contamination of the samples with terrestrial substances, all experiments were carried out in a clean laboratory. As a result, nitrogen, which is part of organic molecules, was discovered in carbonate grains. The authors of the article believe that these substances probably formed on Mars or were brought to the planet’s surface by meteorites.
However, regardless of their origin, the very presence of organic nitrogen-containing compounds on Mars from the Noi period indicates the importance of studying the nitrogen cycle on this planet. If organic matter in a significant quantity and variety was formed or brought to Mars and preserved in its surface layers during the geological ages, this matter had the opportunity to develop in more complex ways. Thorough investigation of Martian meteorites, as well as missions involving the collection of soil samples on Mars and its satellites, will help bring you closer to understanding this process.
Scientists at Brown University previously concluded that ancient Mars had enough hydrogen to support underground life for hundreds of millions of years. We also talked about how astronomers calculated that the period of the potential habitability of Mars was approximately 700 million years.
Evgenia Skaredneva
