Latest lab tests show salt minerals on Mars kill basic life form bacteria, implying the 'Red Planet' is more uninhabitable than previously thought
Hopes of finding life on Mars, at least on the surface, were dealt a blow Thursday by a study revealing that salt minerals present on the Red Planet kill bacteria.
In lab tests on Earth, the compounds known as perchlorates killed cultures of the bacteria Bacillus subtilis, a basic life form, a research duo from the University of Edinburgh's School of Physics and Astronomy reported.
Perchlorates, stable at room temperature, become active at high heat. Mars is very cold.
In the new study, Jennifer Wadsworth and Charles Cockell showed the compound can also be activated by UV light, without heat, in conditions mimicking those on the martian surface.
It killed bacteria within minutes, said the team, implying the planet was "more uninhabitable than previously thought."
"If we want to find life on Mars, we have to take this into consideration and look at trying to find sub-surface life that wouldn't be exposed to these conditions," Wadsworth told AFP.
Perchlorates are natural and man-made on Earth, but are more abundant on Mars where they were first recorded by NASA's Phoenix Lander in 2008.
The fact that perchlorates killed B. subtilis in the presence of UV radiation did not necessarily mean that all other life forms would similarly die, said Wadsworth. Further tests would have to be done to confirm this.
Perchlorates have previously been spotted in lines, thought to be brine streaks, on the surface of Mars.
Their presence was presented as evidence by scientists in 2015 of liquid water on the Red Planet.
But the new study said brine seeps, "although they represent local regions of water availability, could be deleterious to cells" if they contain perchlorates.
The findings do contain some good news.
They mean that organic contaminants left on Mars by robotic exploration, of which B. subtilis is a common one, are unlikely to survive long.
It is widely accepted that the Red Planet once hosted plentiful water in liquid form, and still has water today, albeit frozen in ice underground.
Liquid water is a prerequisite for life as we know it.
Explore further: Mars rover scientist hopes to find more evidence of liquid water
this_mild_idea on July 9th, 2017 at 01:33 UTC »
Not space related, but can anyone tell me why this title should be "more uninhabitable" instead of "less habitable?" Seem like the single negative is more effective / grammatically correct.
COACHREEVES on July 9th, 2017 at 00:23 UTC »
For the next few hundred years I always thought that our Space colonies will be Space Stations perhaps terrarium style ) and O'Neill cylinders.
Actually Living on other planets I think will require us to change us. Genetically modify us to make humans more resistant to radiation, cold, eat (genetically modified) food locally grown that would likely kill us unmodified.
PhyterNL on July 8th, 2017 at 20:46 UTC »
I'm not sure it shows the surface is "more uninhabitable". The surface already lacks water which is about as 'un' uninhabitable as you can get. Microorganisms can be perchlorate resistant, but no life survives without water.
What the study shows is that UV light in combination with the concentration of perchlorates detected in Martian soil samples are enough to kill certain bacteria common in Earth surface soils, which is obviously a poor analogy but of course we don't have Martian bacteria to test on so there's little choice.
In the context of colonization, perchlorates do not represent much of a problem. Earth has a number of perchlorate-resistant halophilic and halotolerant microorganisms that thrive in sodium rich solutions, probably quite suitable for Mars colonization. Perchlorates are also not much a problem for more complex organisms like plants and animals. Perchlorate toxicity is easily monitored and the efficiency of plant uptake of perchlorates has also been well studied. Certain lettuce species for example can completely deplete perchlorates from the substrate in which they're planted. So hypothetically 'cleaning crops' could be grown and disposed, eliminating toxicity and allowing the native soils to being furbished into substrates suitable for sustaining Earth bacteria.