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Terrestrial life unlikely to contaminate Mars: Study

Exploring Mars may not pose risk of contaminating the Martian ecosystems as the climate on the Red Planet is not suitable for terrestrial life as we know it, says a new study.

The findings, published in the journal Nature Astronomy, can help allay some planetary protection concerns even as humans plan to land on the Red Planet.

Modelling the atmosphere of Mars, the researchers found that due to the Red Planet's low temperatures and extremely dry conditions, a droplet of liquid water on its surface would instantly freeze, boil or evaporate, unless the droplet had dissolved salts in it.

This brine would have a lower freezing temperature and would evaporate more slowly than pure liquid water. Salts are found across Mars, so brines could form there, said the study.

"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," said co-author of the study Alejandro Soto from Southwest Research Institute in the US.

"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 results indicate that stable brines on the Martian surface and its shallow subsurface (a few centimetres deep) are not habitable because their water activities and temperatures fall outside the known tolerances for terrestrial life.

"Even extreme life on Earth has its limits, and we found that brine formation from some salts can lead to liquid water over 40 per cent of the Martian surface but only seasonally, during 2 per cent of the Martian year," Soto continued.

"This would preclude life as we know it."

"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," Soto said.

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