Mars has been probed and otherwise studied for signs of life more than an alien cadaver in a sci-fi horror movie, but the Red Planet can’t even be a dead planet if there was never life there to begin with.
Now something that was once thought to be an agent of life on Mars may actually mean that its dusty reddish landscape is even more inhospitable than we thought. The soil is saturated with perchlorates, ions that form when one chlorine atom and four oxygen atoms merge.
Perchlorates factor into many different compounds depending on which element they bind with. Being a salt also means that they can cause the freezing point of water to drastically plummet on the freezing planet. Alien hunters were initially ready to start a party when they discovered extraterrestrial evidence of perchlorates that could have meant the possibility of liquid water on the Martian surface, but the cake and balloons with little green men on them may have to wait.
“The combined effects of at least three components of the Martian surface, activated by surface photochemistry, render the present-day surface more uninhabitable than previously thought,” say Jennifer Wadsworth and Charles S. Cockell of the United Kingdom Centre for Astrobiology at the University of Edinburgh, who led the study and recently published their results in Nature Scientific Reports.
Perchlorates are not a death threat on their own, but new research investigated how they react with the ultraviolet rays constantly attacking Mars and found they turn toxic. Scientists exposed a supposedly immune strain of Bacillus subtilis bacteria to a killer cocktail of perchlorates soaked in UV radiation. When the microbes were totally obliterated in under a minute, they tried the experiment again with several different kinds of perchlorates, but the bacteria were always doomed.
It doesn’t exactly help the search for life when the average daytime temperature on Mars is about 80 degrees Fahrenheit, and that isn’t even counting the negative 195 it can plummet to near the poles when winter blasts it into a deep freeze. Neither does the presence of iron oxides and hydrogen peroxide, which increase cell death tenfold. Never mind the gaping lack of oxygen. UV light is believed to turn perchlorates to poison when it breaks the molecules down into more reactive ions that destroy live cells. Even the ridiculously low temperatures only managed to extend the lifespan of bacteria in the perchlorates for a short time before they succumbed to the bacteriocidal effect. Meaning, life as we know it is unlikely to be crawling around anywhere on Mars.
There are still positives when it comes to perchlorates and Mars. The inability of so much as bacteria to stay alive in such a brutal environment means NASA doesn’t have to worry about spacecraft being contaminated with any microbes from Earth that might have hitched a ride on the equipment—and then calling them aliens.
Radiation poisoning aside, perchlorates are also a superpowered oxidizing agent when heated and used as rocket fuel. At least we can still use them to blast off on a future Martian mission.