NASA’s Perseverance rover has detected the presence of organic chemical compounds in different samples of Martian rocks collected from the floor of Jezero crater, the place where it landed in February 2021. The finding has been published today in the journal Nature.
Although it is not the first time that organic molecules have been found on Mars, and their presence does not necessarily imply the existence of life, their identification and study are of great importance, since these molecules may be precursors of more complex and essential structures for humans. biological processes.
Specifically, Perseverance has discovered aromatic-type organic compounds. These molecules are made up of one or more rings of carbon bonds and with electrons that can circulate through the structure. The simplest example of an aromatic compound is benzene, a ring made up of 6 carbon and 6 hydrogen atoms.
One of the most relevant aspects of the discovery is the confirmation that organic molecules can be stable on Mars and survive, without decomposing, the effects of radiation from space. The planet does not have the protections provided by a magnetic field and atmosphere (Mars’s is too weak to function as a protective shield) and organic compounds are especially vulnerable to incident radiation.
The analyzes carried out by Perseverance also show that the detected molecules are associated with minerals formed in aqueous environments. These humid environments, which we know existed in the past on Mars, could have played a determining role in the synthesis, transport and preservation of organic compounds.
For detection, Perseverance has used the instrument called Sherloc, which has a laser and a spectrometer to study the samples, and which is installed on the robot’s articulated arm.
Without making any contact with the material to be analyzed, Sherloc irradiates it with ultraviolet light. The chemical molecules present in the sample absorb certain ranges of the incident radiation, and later re-emit it with a different energy, a phenomenon called fluorescence. Each type of chemical compound displays a characteristic fluorescence pattern that makes it easy to identify.
In this way, Perseverance has detected the signature compatible with different species of aromatic organic compounds, both single-ring and polycyclic, in the ten locations analysed. However, the identification of exactly which are the detected molecules will have to wait until more complete studies can be carried out in terrestrial laboratories.
Sherloc works in conjunction with Watson, another of the science teams Perseverance’s arm is equipped with. It is a camera capable of obtaining high-definition images that reveal fine details of the textures and structures of the minerals analyzed by Sherloc.
Mars is by far the most studied planet in the solar system beyond Earth. The evidence accumulated by numerous missions, both on the surface and in orbit, have confirmed that this world had abundant liquid water on the surface, in the form of lakes and river currents, between 4,100 and 3,000 million years ago. Then the temperatures were higher than today thanks to a much denser atmosphere made up of carbon dioxide, a greenhouse gas.
The first missions to search for life on Mars were the twin spacecraft of NASA’s Viking project, which arrived there in 1976. The results of the biological experiments they carried created some controversy, when it was believed that one of them had detected signs of metabolism in the analyzed sample, a finding that, almost certainly, was due to a simple chemical process of non-biological origin.
As a consequence of the learning provided by the Viking program, the scientific focus changed and focused on better understanding the present and past of the planet, in terms of its geology, mineralogy and climatology, before attempting again direct exploration in search of life.
Once enough information had been accumulated, thanks to the work of numerous previous missions, NASA once again bet on a project to detect signs of life and in 2020 sent the Perseverance rover to Mars. In reality, scientists believe that the current conditions of the planet are not favorable for life, at least as we understand it, so the bet with Perseverance is to discover evidence that suggests the presence of past life, when lakes and rivers existed on Earth. surface of mars.
During nearly two and a half years of exploration, Perseverance has conducted extensive rock and mineral analysis of the floor of Jezero Crater, a site once occupied by a large lake.
But, in addition, the robot has stored, in small tubes, samples of the most interesting rocks and sediments. So a subsequent mission, which NASA plans to carry out jointly with the European Space Agency (ESA), will travel to Mars to collect these samples and bring them to Earth for detailed study.
This sample transport mission is in the design phase, and it is expected that it can be launched into space around the year 2028 if it receives the necessary funding and return with the Martian material early next year.
The detection of life on Mars, even if it were evidence of its past presence, would be one of the most important discoveries in human history.
It would settle the question of the existence of life outside Earth and would open new frontiers of knowledge in fields such as biochemistry, biology or genetics. And perhaps it could contribute to a better understanding of the origin of life on our own planet.
