Death on the surface of the red planet. A new study by scientists at the University of Edinburgh (UK) has concluded that salt minerals on the surface of Mars kill bacteria in a matter of minutes.
Until now, scientists had their suspicions about whether microorganisms could actually survive on the surface of the red planet. Now, with laboratory tests in hand, the incontestable confirmation that any small green bacteria is doomed in contact with compounds in Martian soil, presents us with the difficult reality of the possibility of growing – potatoes, for example – there.
What is the root of the problem?
The ‘fault’, in this case, lies with the Martian chemical compounds, which contain perchlorates (first detected in 2008). These salty compounds are considered toxic to people, but they are not necessarily a problem for microbes. They are important because they keep surface water in a liquid state (essentially brine) and, it was believed, could also be beneficial to life.
However, the researchers found that when exposed to intense ultraviolet light (replicating the one that exists on Mars), everything becomes very dark for any form of life : the perchlorates killed any trace of bacteria. “Perchlorate, although stable at room temperature, is a powerful oxidant when activated, for example at high temperatures,” the authors write.
The bacteria they conducted the experiments with was Bacillus subtilis , a very common microorganism found on spacecraft. None of the bacteria survived this test. In fact, they died within 30 seconds. Without the presence of perchlorates, the bacteria succumbed in about a minute.
This unfortunate discovery shows that if there is life on Mars, it is likely to be hiding very far below the planet’s surface.
“Our observations show that the surface of present-day Mars is very damaging to cells, caused by a toxic cocktail of oxidants, iron oxides, perchlorates and UV radiation,” the authors conclude in the journal Scientific Reports.
But we can still get a positive side out of all this. If the Martian soil kills terrestrial microbes upon contact, it means that there is less chance that our missions to Mars could contaminate the neighboring planet.
Reference: Perchlorates on Mars enhance the bacteriocidal effects of UV light. Scientific Reports doi: 10.1038 / s41598-017-04910-3
