Last week, the search for life on Mars becamemore interesting. For decades, scientists gazed into the red deserts of this dry and dusty planet, trying to highlight areas in which life could take root billions of years ago when the Martian climate was warm and humid. But on July 25, scientists announced that they had found signs of a large lake with liquid water under a thick layer of ice near the planet’s south pole.
If the existence of the lake is confirmed, perhaps we will find microbes in it.
Overall, this finding has changed the attitudeastrobiologists who want to protect any existing extraterrestrial life from being destroyed by accidentally introduced species from Earth. Mars rovers and descendants are cleaned to strict standards in order to avoid any possible glare, says astrobiologist Lisa Pratt of NASA’s planetary defense department. “Possible subglacial lake! This significantly changes the type of environment we are trying to protect. ”
How will the search for life on Mars change after the discovery of the lake?
First question. Can anyone actually live in this lake?
For most terrestrial microbes it will be harsh.Wednesday. Life on Earth fills every niche that can be found, from cave crystals to arid deserts. But the lower limit of temperature for most of earthly life is -40 degrees Celsius. The temperature of the Martian ice crust is about -68 degrees.
“It's very cold there, colder than in any environment on Earth where, in our opinion, life can exist or reproduce,” says Pratt.
The lake contains a lot of water. But in order for water to remain liquid at such a low temperature, it must be extremely salty. "On Earth, this kind of salt mixture does not allow organisms to live in peace," says planetary scientist Jim Bell of the University of Arizona in Tempe. "Even extremophile bacteria that can live in salt water may not survive."
Can Martians live there?
"Absolutely," says Pratt.
If life originated on Mars in the past, whenthe planet was friendlier, some organisms could adapt to climate change and quietly continue to dwell in cold saline water, she says. “As for me, this is an ideal refuge in which you can just be, maybe dozing and wait until the conditions on the surface become better.
How does this lake differ from other bodies of water in which we hope to find life, like those on Enceladus?
For explorers of the planets, Mars has onea great advantage compared to other ice moons of Saturn and Jupiter: we have already visited it. You can get to Mars relatively quickly, in just 4-11 months, and the atmosphere of the planet makes it easier to land, unlike small airless moons.
A big issue for planetary defense iswhether the lake of Mars contacts the surface. On Enceladus, and possibly on Europe, the liquid water of the subsurface ocean splashes into the sky through cracks in ice. These geysers can significantly simplify the sampling of the ocean: the spacecraft will be enough to fly through it. But the fact that the water goes outside means that germs can move freely.
Although spacecraft have not landed on Mars along with the lake, dust storms can carry pollution throughout the planet.
“If the lake is real, let's hope the passengers haven’t got into it,” says Pratt.
If there is no way to get into the lake or get out of it, how do we know that there is life in it?
This is a big question.
To check the lake for signs of life,“Need to drill to him” the way, says Isaac Smith from the Institute of Planetary Sciences in Lakewood, Colorado. This is how scientists probe similar under-ice lakes on Earth, like Lake Vostok, which scientists from Russia drilled in 2012. At the same time, they stated that the lake was living an active life, but later recognized that the samples were contaminated.
Drilling on Mars could be more technicallydifficult and face the pressure of the scientific community, as is the case with a team from Russia. “Like the subglacial lakes in Antarctica, the lake of Mars can be considered an unusually rare and special place,” says Pratt. "I expect the drilling will meet a lot of resistance."
But if we are lucky, we can do without it. Signs of seasonal changes in methane content in the Martian atmosphere aroused interest among astrobiologists, as they may indicate life below the surface. ExoMars, the apparatus of the European Space Agency and Roscosmos, which began collecting data in April, is looking for more methane.
"ExoMars could find smoke, so to speak," saysthe planetologist Roberto Orosei from the National Institute of Astrophysics in Bologna, Italy, who was on the team that discovered the lake. "Combining liquid water and methane in the atmosphere would be eloquent testimony to what is happening on Mars."