Categories: world

How rain killed life in the boring desert of the world

Be careful what you want – even if you really want something you really need. Take for example the Chilean…

Be careful what you want – even if you really want something you really need. Take for example the Chilean Atacama desert. Considered as the driest place in the world, it has an average rainfall of as little as 0.04 inches per year and meaningful decline of about 1.5 inches (enough to leave short shallow lagoons) on average once a year. Even so much water has been difficult to come with, with climate records indicating that no significant rain has fallen over the past 500 years.

So you would think it would have been welcome when the desert got two storms 2015 and 2017, not to mention a few very few rain events in between. Atacama should – or at least could have broken to life, with which Cornell University astrobiologist Alberto Fairén called “majestic flowers.” But according to a new paper from Fairén and his colleagues, published in the journal Scientific Reports ] that followed was much more dead than life. It has consequences not only on earth but also on expensive planets like Mars.

Although Atacama is an all-but-sterile site, there are some organisms capable of scrapping out an existence there. At least sixteen microbial species are known to fill the deep soils of long dry seabed, using nitrates, a salt form of nitric acid as food. What extremely minimal moisture there is from the rains and what is known as the altiplanic winter, between December and March, when relatively humid air drives across the Andes mountains to the east.

The microbes that can parlaya these indecent relationships in life, the authors write, “are exquisitely adapted to the extremely drought conditions.” It helps in addition to being able to cope with so little water, they are also radiation tolerant, which can survive the intense ultraviolet energy of the Sun bathing in the desert.

After Atacama was bathed by the actual, honest and good water, however, it became rough. Not only did the flowers flow, but when Fairén and his colleagues examined the transient salty lagoons that left the rain, they discovered that on average 1

2 of the microbial species in the soil below had disappeared.

“The extinction event was massive,” Fairen said in a statement that accompanies paper emissions, with up to 87% of all life disappearing in some regions. The cause of death was what is called osmotic shock when single-cell organisms absorb too much water through their outer membranes and burst. If a microbe can drink, then this will happen. It also spells potential bad news for Mars.

For researchers to study hypothetical life in other worlds, Atacama has been considered a good analogue for Mars environment. Like Atacama, Mars was once a very wet place. And like Atacama, the planet lost almost all of its water, but for Mars, it disappeared in space, while Atacama was wiped out due to the changing of climate patterns. Mars water only lasted for about the first billion in its 4.5 billion years, but it would have been enough for at least the microbial life to be formed. Even when the planet was dried out, the hardest of these microbes could have survived, as they did at Atacama. The drying on Mars was uneven, but with single local floods such as underground watercourses were emptied or local duct walls were broken.

“As a result of this,” the authors write, “hypothetical local ecosystems … would have been episodically exposed to even greater osmotic stresses than those we reported here for the Atacama microorganisms.” The result: a microbial microbial death-off .

People visiting Mars can have similar effects on any life that can still be there, at least if we try to make the world a service by giving it some water. In fact, our spacecraft has already done so. In 1976, Viking landlists used aqueous solutions to test life in samples of martian soil and searched for telltale gases that would signal biological processes. That could have been a big mistake. It was not only a decisive proof of life found, but Fairen and his colleagues wrote that water was applied to the cells “would have caused their osmotic blasting first and then the subsequent destruction of the organic molecules.”

There is no proof what happened – but no evidence did not happen either. The search for life on Mars and other worlds will certainly move on, and it should. But ecosystems are ecosystems, no matter what their home planet is, and if we’ve learned something from here on earth, they can be hard to protect and by far easy to destroy.

Write to ] Jeffrey Kluger at [email protected]

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