Organic material found in Mars Crater Lake

If, say, four billion years ago the Earth’s atmosphere was the same as it is now, then we would not be talking to you now – this atmosphere would have been “blown away” into space a long time ago. According to planetary scientists, the most common trend for all worlds in the universe is that their atmospheres lose most of their mass over time. There is a version that initially our atmosphere was as dense as that of Saturn’s satellite Titan, where you can basically attach wings to yourself and soar above the surface with inspiration. And then lighter and more volatile substances were carried into space, and only relatively heavy ones remained.

Roughly the same scenario is expected on Mars. Imagine a planet where the atmosphere is 15 or even 20 times denser than the current Earth, a planet with clouds, lakes, rivers, a greenhouse planet: yes, scientists think Mars was like that several billion years ago. The fact is that this greenhouse existed primarily because of molecular hydrogen, that is, molecules consisting of two hydrogen atoms. It is a very, very greenhouse gas. It is true that it is also extremely volatile. But some of the hydrogen was associated with oxygen and formed water, which filled the craters, flowed into the oceans, and collected in the form of steam in the lower layers of the atmosphere. This happy time lasted for long millions of years. But by geological standards, millions of years is not very long. And yet it is possible that it is enough for the same miracle that happened on Earth to take place: for more and more complex molecules to be assembled from atoms of carbon, nitrogen, oxygen, hydrogen, phosphorus, sulfur, and in the end – the most the amazing molecules of the universe: RNA and DNA.

Photo © NASA/JPL-Caltech/ASU/MSSS

In addition, scientists claim that the very atmosphere of hydrogen and not particularly oxygen on Mars was even more promising for the origin of life than that of Earth: oxygen is not the best element for the formation of prebiotic molecules.

What happened then? And then light molecular hydrogen flew away. This is confirmed, for example, by samples taken by the Curiosity rover (and they are about three billion years old): they contain much more of the heavy isotope hydrogen – deuterium than “classical” hydrogen. The problem is that time, as we see, did not spare even relatively heavy water vapor, which is why we now observe an atmosphere on Mars so rare that on Earth it is only at an altitude of 35 kilometers. But here we also have to remember that Mars has a very weak magnetic field, and the magnetic field is, as you know, a shield from solar and galactic radiation. Without it, this radiation bombards the atoms and easily carries them away with its wind.

Has the doomed planet managed to become happy, that is, to give rise to life? If you are looking for the answer to this question, then somewhere at the bottom of the former Martian reservoir. That’s why the crater lake was chosen for the Perseverance rover: the images clearly show that meandering channels of dry rivers border it. The rover has been touring there for the second year now and has collected a total of 12 soil samples from different locations so far. But if the rover previously encountered rocks mainly of igneous origin, the last four samples were taken from the river delta, that is, these are sedimentary rocks. Namely, particles of rock, which was called the “wildcat’s ridge” – Wildcat Ridge: it is quite clear to planetary scientists that it was formed from sand and everything else in the process of evaporation of a salt reservoir. So scientists were happy to report that some organic matter was found in this ridge, that is, the very building blocks of life. On Earth, ancient fossils of bacteria are found in such rocks. The researchers note that this is not the first time that organic substances have been found on Mars, but in this case they turned out to be exactly where it would be most convenient for prehistoric micro-Martians to live.

Rocks taken on Mars.  Photo © NASA/JPL-Caltech/ASU/MSSS

Rocks taken on Mars. Photo © NASA/JPL-Caltech/ASU/MSSS

By the way, earlier at the Space Research Institute they told Life that the predecessor of Perseverance, the Curiosity rover, actually did not even find organic matter, but very specific traces of living organisms, but the problem was and remains that it is necessary to prove that they were not retrieved from earth: no matter how you sterilize space technology, something living may well go on an interplanetary journey with it.

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Two endurance tests taken. Photo © NASA/JPL-Caltech/ASU/MSSS

What would you say if you were shown fossils of alien bacteria?

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