During one of the recent studies on the Red Planet, an underground reservoir was found - a good sign in terms of the likelihood of life there.
The new study, published on the morning of July 25th, has provided exciting evidence for liquid water beneath the surface of Mars. As a result, questions arise: can life be hiding in this environment, and what does it look like?
These questions are not confined to science fiction writers. Scientists have wondered over them for years, using direct and indirect observations of conditions on the planet to figure out what Martian life might be like - if it is there, or has ever been.
For example, in 2009, the Phoenix lander directly confirmed that there is water ice on the surface of Mars. An employee of the University of Washington, Dirk Schulze-Makush, said in an interview: “I would be very surprised if Mars were completely sterile. Once life takes root, it will find a way to maintain itself in ecological niches."
Life underground
Thanks to new research, one of these niches looks like an underground reservoir filled with salt water. The water there is at least twice as salty as the sea. In a sense, this is even good for the existence of life, because salt water does not freeze as easily as fresh water, and this is important, since the water temperature under the surface of Mars should be somewhere between minus 10-30 degrees Celsius. But there is some bad news too. Martian water will be full of perchloric acid salts, toxic to most forms of life on Earth. Most, but not all. A bacteria called Dechloromonas aromatica reduces the concentration of these salts by breaking them down into chlorine and oxygen, which is breathed in. These babies instinctively move towards the concentration of perchloric acid salts. Such organisms are called chemotrophic,since their growth is due to certain external chemical stimuli (but phototrophs live on the surface and receive chemical energy from sunlight).
Perhaps, somewhere deep below the surface of Mars, living organisms use some kind of chemical substances for survival, just like it happens on the bottom of the earth's seas and oceans. Samuel Kounaves, professor of chemistry at Tufts University and one of the leading scientists of the Phoenix project, recently told the online journal of astrobiology that some chemotrophic bacteria could live on Mars, using perchloric acid salts as an energy source - “maybe, there is a whole ecosystem, including liquid water."
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Methane secrets
In December 2014, NASA's Curiosity rover detected a methane burst ten times the normal level. This gave rise to conclusions about the existence deep underground of certain life forms that produce this gas.
Since then, Curiosity has taken up interplanetary geology. According to NASA, "rock chemistry could generate methane, but scientists cannot rule out the possibility of its biological origin." In this case, methane will seep from underground reservoirs, such as that was seen from the orbit of the Red Planet. It is also possible for the existence of such life forms that methane replaced oxygen as a vital element. This possibility is being considered by many Titan researchers.
To what extent can a hypothetical underground ecosystem on Mars grow? Chemotrophs tend to multiply rapidly. Take Hydrogenovibrio crunogenus, a bacteria that lives by converting sulfur from geothermal sources on the seabed into oxygen. If there is enough sulfur, the amount can double every hour. Care will need to be taken when drilling and sending samples to Earth.
What about complex life forms?
Could more complex organisms be found in the Martian environment? On Earth, in deep-sea depressions, larger animals like shrimp are helped by heat, which gets to them from the surface through organic materials. And some crabs and shrimps first accumulate a layer of bacteria on their bodies for further nutrition.
It is difficult to say what could have happened under the surface of Mars over the millennia. The amount of chemical energy available can limit the size of the creatures living there, but it's best not to rule out either option. In cold environments, organisms generally survive by forming symbiotic relationships with other organisms, making the interactions between Martian bacteria difficult to understand but impressive.
The most tenacious creature on Earth is considered to be a water bear, also known as a tardigrade, a microscopic invertebrate that lives in mosses, soil and lichens. They can survive in temperatures ranging from minus 253 to plus 151 degrees Celsius. So the cold won't kill them. But water bears, like most highly developed organisms, still need oxygen to survive.
As for life on Mars, there are, of course, many options. Bacterial colonies can produce oxygen from sulfuric acid, the same chemical that keeps water from freezing. And if bacteria are capable of producing oxygen, something larger and more durable may exist on the Red Planet. Perhaps the development of life is aided by some chemical alternative to oxygen, obtained from methane.
Until we start drilling, we won't know.
Joe Pappalardo