Only in the past few months have we learned of new evidence that complex organic molecules have survived in Martian rocks. Each of these discoveries is another reason to look for extraterrestrial organisms on the surface of Mars, they write "7 Days". Perhaps soon we will find the first evidence that life exists not only on our planet?
Only in the past few months have we learned of new evidence that the Martian rocks retained complex organic molecules, presumably essential for life; that there are seasonal variations in methane in the atmosphere of Mars; and under the surface of the planet itself there are huge reserves of liquid water.
Each of these discoveries is another reason to look for extraterrestrial organisms on the surface of Mars. Perhaps soon we will find the first evidence that life exists not only on our planet?
And while the signs of once-existing alien life would be an incredible discovery, we are faced with an even bigger question: What does Mars mean for future life?
Life on Mars … What news it would be! However, it would be a mistake to assume that last summer's discoveries mean that we will see something similar.
To begin with, the 4.6 billion-year history of Mars is complex and sad. Ancient Mars was a completely different planet. In fact, Mars resembled Earth. Its atmosphere trapped heat and was protected by a magnetic field that was able to stop cosmic radiation and ultraviolet rays, and the planet's surface was almost certainly teeming with huge bodies of water that could support life as we know it.
"Scientists agree that Mars most likely resembled a typical summer Arctic day," said Natalie Cabrol, a NASA astrobiologist who is actively involved in the search for signs of alien life on Mars. - For life to exist, you need energy, water, nutrients, shelter, and all this was once on Mars. If there was a time when life could have arisen, it was the era of early Mars."
But today Mars is very different. Even in the most ideal conditions, such as on a summer day, the temperature on Mars can reach almost 70 degrees Fahrenheit.
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But at night the temperature drops to below -100 degrees. Mars does not have the atmosphere that would keep the climate warm and temperate. And Mars lost its magnetic field long ago, which means there is still radiation on the surface.
“I always compare it to the kitchen,” says Cabrol. - There are ingredients on the table. Two people can mix these ingredients and get the same results. But if one of them is a great chef, and the other is a complete zero in cooking, you get two different dishes."
These two chefs are Earth and Mars, respectively. And, although the Earth has managed to cook all kinds of biological delicacies, Mars was unlikely to be able to make something edible.
Three months ago, the Curiosity rover near the Martian equator stumbled upon a mountain three miles high - Gale Crater, whose valley appeared to contain methane, a sign of primitive organic life.
But scientists are in no hurry to draw conclusions about the structure of organic substances. "The chemical structure [of the molecules], as far as we know, is pretty random," says Roger Everett Sammons, a planetary scientist at MIT and a member of the team that discovered Gale Crater.
They are, chemically speaking, the building blocks of life, but they lack the structure that actually allows them to become part of a living organism. It's a bit like how concrete is not cut into small blocks, but into strangely shaped pieces from which nothing can be built.
“The fact that [these organic substances] are still around after millions of years of cosmic radiation and UV waves speaks volumes about the stability of these materials,” explains Sammons. "But that says nothing about their origin."
Summons believes that because of their structure, organic molecules did not form on Mars, but ended up on the red planet as part of meteorites.
Dirk Schulze-Makuch, a German astrobiologist and professor at the Technical University of Berlin, interprets the structure of organics differently and believes that it may be a sign of pre-existing extraterrestrial life.
But he also notes that these organic matter are showing signs of degradation. “This process is not going in the opposite direction, towards life,” he said. - It goes in the direction of decay. It would be appropriate to assume that these molecules were once part of organisms or, less likely, meteorites from space. But they will not develop into life."
Even if conditions on Mars changed, becoming more favorable - say, people would settle on it and reshape the red planet into Earth 2.0 - Schulze-Makuch doubts that molecules have the necessary chemical structure to come together and create life.
“Even in today's earthly conditions, I don’t think we will be able to see the beginning of life,” he explains. - Oxygen will immediately begin to oxidize organic molecules. The same thing will happen on Mars - cosmic radiation easily oxidizes molecules, so we won't get the desired fusion reaction. I do not see a realistic development of events on Mars when this could happen."
Caroline Freyssinette, at the Laboratory of Atmosphere (LATMOS) at the French National Center for Scientific Research and another member of the Gale crater discovery team, also pointed out that even if all of the above problems did not exist, the main reason why these molecules could not create new life on Mars, will remain the same: there are not enough of them on the planet.
“You can touch the soil on the surface of the Earth and find more organic matter there than on all of Mars,” she says.
“We know that life is like a disease,” explains Cabrol. - It is very difficult to get rid of her! If life had arisen on the surface of Mars, it would not have stopped so easily and would still be there”.
So, what would this life look like on today's Mars? Cabrol has done much of her research in this area, studying some of the harshest, coldest places on Earth, including microbes called extremophiles that have survived these conditions. These environments are the closest terrestrial counterparts of potential Martian life.
In her opinion, extremophile endoliths that live in the clay of porous rocks are most reminiscent of what we can find on Mars, if anything else is there.