Scientists Have Assessed The Possibility Of Life In The Salt Brines Of Mars
American scientists have modeled the conditions that could exist in liquid salt brines on the Martian surface and concluded that the presence of life inside is questionable, according to the publication in the Nature Astronomy.
Because of the low temperatures and humidity, the presence of water on Mars is impossible, but salt brines that retain, at certain concentrations, a liquid state even at very low temperatures, may well exist on the surface of the red planet. At certain temperatures and humidity, salts on the planet's surface can begin to absorb water from the atmosphere, forming a salty liquid. Earlier, cameras recorded the formation of salt solution drops on the hot rack of the Phoenix lander.
American scientists have modeled conditions on Mars to understand whether life can exist in these brines and whether there is a risk of contamination of Martian samples with microorganisms brought from Earth.
"Our team studied specific regions on Mars where liquid water temperatures could allow known terrestrial organisms to reproduce," one of the study's authors, Dr. Alejandro Soto of the Southwest Research Institute, said in a press release. We used climate information from both atmospheric models and spacecraft measurements. Our model predicts where, when, and for how long brines will be stable on the surface and at a shallow depth below the surface of Mars."
"We have been conducting experiments at the University of Arkansas for many years to study the types of reactions that occur in the conditions of Mars. Based on laboratory data, we can predict what is happening on the surface of the planet," explains one of the authors of the study, Dr. Vincent Chevrier from the University of Arkansas.
The simulation results showed that the maximum possible temperature of liquid brines in the super-dry conditions of Mars is about minus 48 degrees Celsius. Such temperatures are possible only on 40 percent of the surface of Mars, but only during very short seasonal intervals, which make up about two percent of the Martian year and no more than six hours in a row. In the depths of the Martian soil, at a depth of up to eight centimeters, liquid salt brines can exist a little longer, during 10 percent of the Martian year.
Despite that this range is much wider than previously thought, even the most extreme representatives of terrestrial microorganisms can not survive at such low temperatures.
"This excludes life in the form in which we know it," notes Soto. "We have shown that on a planetary scale, the surface of Mars and the shallow interior is not suitable for terrestrial organisms since liquids can only be formed thereat rare moments of time," concludes the first author of the article, Dr. Edgar Rivera-Valentin from the lunar and planetary Institute (LPI) of the United States.
Scientists believe that there is no fear that future missions to Mars will bring terrestrial microorganisms there.