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Salty Martian

water may hold

oxygen for life

THE atmosphere of Mars may not
contain much oxygen, but that doesn’t
necessarily mean the planet itself
lacks the stuff. A calculation of how
much oxygen could be dissolved in
salty Martian groundwater shows
that the dusty world may be hiding
an abundance of oxygen under its
surface – potentially enough to
support life.
We know Mars has oxygen on its
surface, which is why it looks red:
iron in Martian dust mixes with
oxygen to create rust.
Vlada Stamenkovic´ at NASA’s Jet DANIEL VIÑÉ GARCIA/GETTY
Propulsion Laboratory in California
and his colleagues calculated how
much oxygen could be dissolved in
brines just under the planet’s surface. western United States,” he says.
They found that, under particularly Australia’s Grand Beyond extending the Grand
cold conditions, certain types of Canyon’s reach across the
brines could hold just as much Canyon connection Pacific and into the southern
oxygen as seawater does on Earth. hemisphere, uniting the
This would be enough for microbes Tasmanian rocks with those in
and even simple animals like sponges North America helps to solve an
to survive (Nature Geoscience, Lucas Joel didn’t look a lot like similarly ancient geological jigsaw puzzle.
doi. org/ cv2v). aged rocks nearby.” About a billion years ago, all
But we aren’t entirely certain THE Grand Canyon in Arizona Mulder and his colleagues of Earth’s continental plates
there are liquid brines on Mars. has a bizarre Antipodean link. have now found that the rocks formed a single supercontinent
Despite clues, such as recurring A chunk of the rock sequence that contain minerals with the same
slope lineae – dark lines flowing down has been sliced through to form “geochemical fingerprint” “We concluded that
hills that appear to be liquid – there this natural wonder of the world as those in the Grand Canyon Tasmania must have
is no definitive proof on which all now sits thousands of kilometres (Geology, doi.org/cv24). been attached to the
researchers can agree. away in Tasmania, Australia. “We concluded that although western United States”
“There have been various different To peer into the Grand Canyon it’s now on the opposite side
claims for where we may or may not is to behold, in its rock layers, a of the planet, Tasmania must called Rodinia. But working
have seen evidence for these brines record of Earth’s distant past. The have been attached to the out exactly how today’s
existing,” says Kirsten Siebach at Rice oldest layers at the bottom date continents would once have
University in Texas. “Small amounts back more than 1.5 billion years. fitted together to form Rodinia
of brines would be possible, but we It is some of the most ancient is no simple task given how long
aren’t sure that they’re really there.” layers in the sequence that ago it existed. The Tasmanian
Even if Mars does have oxygen-rich interest Jack Mulder, a geologist discovery provides a clue because
brine, that’s no guarantee of life, at Australia’s Monash University. it is clear evidence that North
says Robin Wordsworth at Harvard He thinks these rocks – which are America and Australia were linked
University. “It’s two sides of the coin between about 1.1 and 1.2 billion together at the time.
in a way,” he says. “If you want years old – look just like similarly “Jack’s paper shows that
respiration, oxygen is good, but too ancient rocks in Tasmania. Tasmania holds the key to tying
much oxidation can be bad for life.” The Tasmanian rocks in together the tectonic geography of
Compounds like hydrogen peroxide question have always seemed a the time,” says Alan Collins at the
can damage cells, which may be bit out of place, he says. “They University of Adelaide, Australia.
particularly bad for primitive life forms “It’s really a good link and tie that
that don’t have that many cells to These Tasmanian rocks were once JACK MULDER allows us to build full plate models
begin with. Leah Crane ■ part of the Grand Canyon (top) of the ancient Earth.” ■

27 October 2018 | NewScientist | 7