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https://www.bbc.com/future/article/20260130-how-deep-caves-are-transforming-our-search-for-extraterrestrial-life>
“"The wall was bright green. It was the most iridescent green you'd ever seen,
and yet the microbes were living in complete darkness," says Barton, professor
of geological sciences at the University of Alabama.
Beneath the deep rocky canyons of the Chihuahuan Desert in southern New Mexico,
lies a network of 119 caves. The caves, part of the Carlsbad Caverns National
Park, formed four to 11 million years ago due to sulphuric acid dissolving the
limestone rocks.
The primary attraction of the park is the show cave, Carlsbad Cavern. Here,
glittering stalactites cling to the roof of the Big Room, a huge underground
chamber measuring almost 4,000ft (1,220m) long and 625ft (191m) wide.
"The Carlsbad cavern is very easily accessible. It's a very large limestone
cave that tourists can visit that has steps and ladders and everyone can go
down," says Lars Behrendt, a microbial biologist at Uppsala University. Parts
of the cave system, he adds, are even wheelchair accessible.
Almost 350,000 people visit Carlsbad cavern each year, yet most would be
completely unaware that the cave is the setting to one of the most baffling
scientific discoveries of the past decade. In the seemingly pitch dark,
microbes were able to harness light for energy – the same kind of light given
off by red dwarf stars, the most common kind of star in our galaxy. This, says
Barton, means we can search for extraterrestrial life in more places than
prevously thought.
In 2018, Behrendt had just finished his PhD. He had also won an academic prize,
which awarded him some money. He contacted Barton and asked her if she would
accompany him on an expedition. Luckily, she agreed.
"The first thing you do in the Carlsbad cave is you kind of go down on the
tourist trail, and then you turn around a corner," says Barton. "I don't know
how many times I've done that trail, probably 40 times. At that point, you go
around the corner, and then behind you there's an alcove, and it's completely
black."
For more than 20 years, Barton has been studying microscopic life found deep
underground. Yet what happened next was a surprise, even to her.
Behrendt shone a torch on the wall. Although the alcove was pitch black, the
light revealed a blanket of green microbes clinging to the wall. Later tests
revealed they were cyanobacteria; single celled organisms related to bacteria.
Unlike most bacteria, though, cyanobacteria (also known as blue-green algae)
use light from the Sun to make food.
"We started going deeper and deeper into the cave," says Barton. "Eventually we
were a point where we couldn't see without using flashlights. We had to use a
headlight to be able to see our hand in front of our face, and yet you could
still see green pigment on the wall."
Plants are green due to a chemical called chlorophyll, which absorbs light
energy. In photosynthesis, this energy is used to convert carbon dioxide and
water into glucose and oxygen. The process is much the same in cyanobacteria.
Yet here, in the cave, there was no sunlight.
So what was going on?”
Via Esther Schindler.
Share and enjoy,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
