The surface of Mars might be wetter than people imagined, but the salty, cold puddles on its surface won’t harbour life, scientists have said.
A study published in Nature Astronomy examined the idea that salty water might be able to survive on the Red Planet – even though water can’t.
Mars is so cold and dry that if a liquid water droplet is placed on the planet, it would nearly instantaneously either freeze, boil or evaporate away.
But salty water (or brine) would evaporate more slowly and could survive there, researchers believe.
Dr Edgard G Rivera-Valentín, of the Lunar and Planetary Institute (LPI), said: “Life on Earth, even extreme life, has certain environmental limits that it can withstand.
“We investigated the distribution and chemistry of stable liquids on Mars to understand whether these environments would be suitable to at least extreme life on Earth.”
The team of researchers used laboratory measurements of Mars salts along with Martian climate information to predict where brines would form.
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They found that brine formation from some salts can lead to liquid water over 40% of the Martian surface but only seasonally, during 2% of the Martian year.
Rivera-Valentín said: “In our work, we show that the highest temperature a stable brine will experience on Mars is -48°C.
“This is well below the lowest temperature we know life can tolerate.”
The researchers said the finding means it’s less likely that missions to Mars could contaminate the surface with Earthly life.
Rivera-Valentín said: “We have shown that on a planetary scale the Martian surface and shallow subsurface would not be suitable for terrestrial organisms because liquids can only form at rare times, and even then, they form under harsh conditions.
“However, there might be unexplored life on Earth that would be happy under these conditions.”
More environmental data from Mars, such as through the upcoming Mars 2020 mission to Jezero crater, along with further exploration of Earth’s biome may shed some light on the potential to finding life on Mars today.