Chances that life exists on the surface of Mars are dwindling, according to a report released Thursday, which shows that the planet is coated with toxic chemicals that can wipe out living organisms, rendering it “more uninhabitable than previously thought.”
When exposed to ultraviolet light, perchlorates, the class of chemical compounds on Mars’ surface, turn deadly for bacteria.
“We report the significant bacteriocidal effects of UV-irradiated perchlorate on life at ambient temperatures and under Martian conditions,” the study’s authors write.
The discovery suggests that life-seeking missions to Mars will have to dig layers deep to possibly uncover signs of past or present alien life.
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Signs of life are more likely to be found two or three meters beneath the planet’s surface, in an environment that’s protected from intense radiation, The Guardian reports.
“At those depths, it’s possible Martian life may survive,” Jennifer Wadsworth, a postgraduate astrobiologist at Edinburgh University and co-author of the study said.
Perchlorates were first discovered in Martian soil by Nasa’s 40-year-old Viking lander missions. More recent missions have confirmed their presence.
Wadsworth and astrobiologist Charles Cockell found that when perchlorates are exposed to ultraviolet light, they kill bacteria twice as fast as UV light alone.
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Even worse, iron oxides and hydrogen peroxide, which are both present in Martian soil, kill bacteria 11 times faster when mixed with perchlorates and hit by UV light than UV light alone.
The European Space Agency’s ExoMars rover is set to launch in 2020 and is equipped with a drill capable of digging several feet below the surface, where there are possibly signs of life.
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