What Can Earth's Deserts Teach Us About Martian Life?

To prepare for the search for microbial life on Mars, researchers are probing some of the harshest environments on Earth -- like the Atacama Desert. Learn how this work will inform future space missions in today's episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from how Stuff Works, Hey, brain Stuff,
Lauren Vogel bomb here. When it comes to searching for
microbes on Mars, sending a robotic rover to the most
arid environment on Earth is a fine place to start.
As described in a study recently published in the journal
Frontiers and Microbiology, a team of researchers explored the extreme

(00:22):
environment of Chile's Atacama Desert. They wanted to develop strategies
that future robotic explorers could use to seek out the
hiding places of Martian microbes. Both NASA and the European
Space Agency will launch their first life hunting rovers to
the Red planet, the Mars Exo Mars Rover missions, respectively,
so mission managers will need to know where to look.

(00:45):
The Atacama Desert is about as extreme as it gets
for life to eke out an existence, and not only
is the region bone dry, the core of the desert
doesn't get any rainfall for decades at a time, but
because of its elevation, it also receives high levels of
damaging ultraviolet radiation. Plus the soil is extremely salty. These
factors should make the Atacama Desert toxic for life, but

(01:07):
according to team leader stuff In Pointing, a professor at
Yale and US College in Singapore, some of the bacteria
just below the surface quote survive right at the limit
of habitability, and this is very good news for the
prospect of finding microbes on Mars. Pointings team deployed an
autonomous rover mounted drill and sampling device in the Atacama
Desert to see if it could extract soil samples containing

(01:29):
microbes down to a depth of eight centimeters that's a
little over two and a half feet. As a comparison,
samples were also dug up by hand through DNA sequencing.
The researchers found that the bacterial life and the samples
from both methods were similar, confirming that these hardy bacteria
exist and the autonomous extraction method was successful. This test

(01:49):
run shores up hope that if similarly hardy microbes also
thrived just below the Martian surface, a robot could find them. However,
finding microbial biosignatures on Mars could be very challenging for
a remotely operated Mars rover. The researchers found that the
subsurface population of bacteria were extremely patchy, correlating with increased
salt levels that restricted the availability of water. Pointing put

(02:12):
it this way, The patchy nature of the colonization suggest
the rover would be faced with a needle in a
haystack scenario. In the search for Martian bacteria, previous studies
have described the ubiquitous population of relatively unremarkable photosynthetic bacteria
that populate the surface of the desert in Chile. These
are microorganisms that get their energy from sunlight. Things start

(02:33):
to get a lot more interesting and indeed more alien,
just below the surface, Pointing said, we saw that with
increasing depth, the bacterial community became dominated by bacteria that
can thrive in extremely salty and alkaline soils. They in
turn were replaced at depths down to eighty centimeters by
a single specific group of bacteria that survived by metabolizing methane.

(02:55):
These specialized microbes have been found before in deep mind
shafts and other subterranean environment, but they've never been seen
beneath the surface of an arid desert. Pointing said, the
communities of bacteria that we discovered were remarkably lacking in complexity,
and this likely reflects the extreme stress under which they develop.
Finding highly specialized microbes that can thrive in the extremely dry,

(03:16):
salty and alkaline Mars. Like soils in the Atacama Desert
suggest methane utilizing bacteria could also thrive on the Red planet.
Elevated levels of methane have been observed on Mars by
various spacecraft over the years, most recently measures made by
NASA's Curiosity Rover, and that's a big deal. On Earth,
biological and geological processes generate methane, and in turn, microbes

(03:38):
can metabolize methane for energy. The discovery of methane in
the Martian atmosphere could mean there's some kind of active
biology going on underground. To confirm this, we need microbe
seeking missions that will drill below the surface, and now
we have a strategy to track them down. Should microbial
life be found on Mars, it would undoubtedly be the
most significant scientific discovery in human history. But in the

(04:00):
proud human tradition of naming new things, what would we
call our newly discovered Martian neighbors? Would we just copy
the system of how we name life on Earth? Pointing said,
the way we assign Latin names to terrestrial bacteria is
based on their evolutionary relationship to each other, and we
measure that using their genetic code. The naming of Martian
bacteria would require a completely new set of Latin names

(04:21):
at the highest level, if Martian bacteria were a completely
separate evolutionary lineage, that is, they evolved from a different
common ancestor to Earth bacteria in a second genesis event. Granted,
if we find the genetic code of Mars life to
be similar to Earth life, it could be that life
was transferred from Earth to Mars in the ancient past
via a massive impact, a mechanism known as pan spermia.

(04:43):
But if we find a truly novel genetic code that
emerged on Mars, the implications for our understanding of life
would be profound. Pointing said, if we find truly native
Martian bacteria, I would love to name one and call
it planet a desert a supersities, which translates in Latin
to survive on the desert planet. Today's episode was written

(05:07):
by Ian O'Neill and produced by Tyler Clain for iHeartMedia
and How Stuff Works. For more on this and lots
of other hardy topics, visit our home planet how stuff
Works dot Com.