The Red Planet’s harsh conditions prevent the building block of life, water, from being stable. Instead, any water that has found its way to the surface would instantly vaporise, freeze or boil. There is, however, some hope microbial life could thrive in shallow, salty pools of liquid.
Because of their salt content, these potential pools of brine have a much lower freezing point and evaporate much more slowly.
Scientists know of salt deposits on the planet’s surface, so there is hope these briny pools exist.
Life on Earth has already shown an ability to survive in similar, extreme conditions, sparking hope the same could be said of Mars.
But a new study carried out by a Southwest Research Institute (SwRI) scientist in the US could dash all hopes finding alien life on Mars.
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According to a Dr Alejandro Soto, a senior research scientist at SwRI’s, the planet’s atmospheric conditions are too harsh for even briny water to be habitable.
He said: “Our team looked at specific regions on Mars – areas where liquid water temperature and accessibility limits could possibly allow known terrestrial organisms to replicate – to understand if they could be habitable.
“We used Martian climate information from both atmospheric models and spacecraft measurements.
“We developed a model to predict where, when and for how long brines are stable on the surface and shallow subsurface of Mars.”
The study’s findings were published in the journal Nature Astronomy.
This would preclude life as we know it
According to the study, brines can form and remain on the planet’s surface for “a few percent of the year for up to six consecutive hours”.
Beyond that, however, the study has found the brines are not habitable as they exist at maximum temperatures of about -55F (-48C) degrees.
The temperatures, Dr Soto and his colleagues noted in the study, “fall outside the known tolerances” for Earth-based life.
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Dr Soto said: “Even extreme life on Earth has limits, and we found that brine formation from some salts can lead to liquid water over 40 percent of the Martian surface but only seasonally, during two percent of the Martian years.
“This would preclude life as we know it.”
If life does exist in these potential brines, then it does not resemble anything seen on Earth.
Dr Soto also believes the findings lower the risk of cross-contamination by any future explorers who make their way to the Red Planet.
He said: “These new results reduce some of the risk of exploring the Red Planet while also contributing to future work on the potential for habitable conditions on Mars.”
Scientists are hopeful missions like NASA’s Curiosity rover and the Mars Perseverance rover will stumble upon evidence of past life on Mars.
Before it became the barren desert it is now, the Red Planet once resembled a young Earth, with a thick and humid atmosphere and liquid oceans.
NASA said: “Even if there were no life on Mars, it would be exciting to know whether there used to be life there.
“So in addition to looking for living bacteria, NASA will be searching for tiny fossils that might indicate life got a start early in Mars’ history but, unlike on our home planet, it did not survive and evolve into larger life forms.”