Four billion years ago, the surface of Mars appeared to be quite habitable. Rivers and lakes flowed along it, there was even a deep ocean. Some astrobiologists regard ancient Mars as a cradle for life, even more suitable than the Earth, and suspect that life on our planet may have appeared long ago on Martian rocks and was thrown into space by a powerful blow.
Everything changed when Mars lost its global magnetic field. Charged particles emanating from the Sun, were able to carry away the Martian atmosphere, and she gradually exhausted. This process turned Mars into a cold, dry world that we see today, another 3.7 billion years ago. Earth has a global magnetic field left, which explains the suitability of our planet for life.
But such a turn of events does not mean that Mars today is a dead planet.
“If life was on Mars 4 billion years ago, life is on Mars now. Nothing that would have destroyed life has happened on Mars, ”says Michael Finney, co-founder of The Genome Partnership, a non-profit organization that holds conferences on the subject of advances in biology and genome technology.
“If life had been on Mars, it would have gone somewhere, it might have hidden, but it probably would have been still there,” Finney says.
Life on Mars in the Underground
One of the most promising shelters for life will be the underground part of Mars. Although on the surface of the Red Planet today there is no liquid water – except, perhaps, temporary streams on warm slopes – in underground aquifers, most likely, a lot of moisture. Observations of the Mars Express orbiter in Europe show that a large lake can hide under the southern pole of the Red Planet.
The motley inhabitants of the Earth talk about their presence in a very obvious way; An advanced alien civilization could probably quickly understand the existence of life on our planet, simply by scanning our atmosphere.
We do not see such obvious traces in the Martian air, but recently scientists have found some interesting things. NASA’s Ciuriosity rover went through two streams of methane in the 154-kilometer-wide Gale crater. This crater six-wheeled robot explores from the very moment of landing in 2012. The mission of the rover also determined that the concentrations of methane in the air in the Gale crater vary with the season.
More than 90% of methane in the Earth’s atmosphere is produced by microbes and other organisms, so it is quite possible that this gas speaks of modern Martian life.
But disputes on this subject are still underway. Methane can also produce lifeless processes, for example, the reaction of hot water with certain rocks. And even if Martian methane is of biological origin, the creatures that created it can be long dead. Scientists believe that the methane geysers on the Red Planet made their way out of the ground and no one knows how long the gas layer remained sharpened below, before making its way to the surface.
Looking for Martian DNA
NASA’s Mars Rover, which will travel to the planet in 2020, next summer, will look for signs of a long-dead life. The European-Russian ExoMars rover, whose mission will begin at about the same time, will also do the same.
But some scientists want to expand this hunt and to life, which can exist to this day. One of them was molecular biologist Gary Ruvkun, who works at the Massachusetts General Hospital and Harvard Medical School.
Ruwkun is one of the three main researchers in the Search for Extraterrestrial Genomes Project (SETG), which is developing a tool for detecting past or present life based on DNA or RNA on Mars and other alien worlds.
Part of this idea is based on panspermia, the idea that life has spread widely throughout the solar system, and possibly throughout the galaxy, in a natural or artificial way. If life really came to Earth from somewhere else, the likelihood is high that it once flourished on Mars. The red planet could become the source of life, or it was “seeded” like the Earth.
Ruvkun considers panspermia as a very plausible theory. He believes that the main argument in its favor is the very early appearance of ATP synthase, an enzyme that provides the appearance of the adenosine triphosphate molecule.
ATP synthase, according to Ruwkun, fully goes back to the foundation of the tree of life on Earth, which means that this complex molecule appeared about 4 billion years ago.
“It’s not just that life has even appeared. The fact is that she developed too quickly. That is why the idea of panspermia is so attractive. ”
If panspermia is true, any life forms that we find on Mars – or anywhere else in our solar system – are likely to be associated with us. That is, such organisms will use DNA or RNA as their genetic molecule. So we must look for this material.
“It would be foolish not to look for DNA on Mars,” says Ruwkun. “This is an experiment worth doing.”
Not only mars
Mars is not the only place in our solar system where alien life could flourish today. Most astrobiologists would place the Red Planet at the end of the list, putting Europe and the satellites of Enceladus and Titan ahead of Jupiter’s moon.
Under the ice sheets of Europe and Enceladus deep oceans with salty liquid water are hiding. On Titan, too, is believed to have a water ocean, and on the surface of this satellite found lakes and seas with liquid hydrocarbons.
Even a red-hot Venus could have quite habitable spaces.
Like Mars, Venus was once rich in water on the surface, but the irresistible greenhouse effect roasted everything and left the planet with temperatures at which lead melts. However, at an altitude of 50 kilometers above the surface of Venus, it is possible to live.
What do you think, on what planet will the first extraterrestrial life be found?