Updated
at 2:35 pm ET
Ancient
water may lie hidden within the largest volcano on Mars, researchers now say,
and they speculate that such a setup could also harbor life.
While
there is no
firm evidence that Mars does or ever has hosted life, one of the
prerequisites would be water. The surface of the red planet is bone dry, but
several studies have shown liquid water may once have flowed on Mars and could
still exist in pockets below the surface.
The
Martian volcano Olympus
Mons is about three times the height of Mount Everest, with gentle slopes
that sprawl across more than 150 miles of the planet surface. The widespread
volcanic material suggests the presence of water-formed clay which can reduce
friction — an effect seen on Earth at volcanoes in Hawaii.
"What
we were analyzing was the structure of Olympus Mons, why it's shaped the way it
is," said Patrick McGovern, a geophysicist at the NASA-affiliated Lunar
and Planetary Institute in Houston. "What we found has implications
for life — but implications are what go at the end of a paper."
Olympus
Mons soars 15 miles (24 km) above the surface, dwarfing the largest terrestrial
volcano, Mauna Loa, which is just 6 miles (9 km) high, including the portion of
the volcano that extends underwater to the sea floor.
NASA's
hard-digging Phoenix lander uncovered
water ice last year near the Martian North Pole. So some researchers think
it's reasonable to suspect water that may lie trapped underneath the largest
volcano in the solar system, although many suspect that remaining water on the
planet remains ice-locked.
McGovern
and Julia Morgan, a Rice University geologist, used computer models to simulate
how Olympus Mons might have formed. They concluded that only ancient clay
sediments could account for the volcano's asymmetric shape.
Any
existence of clay sediment would certainly indicate water at some point, said
Jack Farmer, an astrobiologist at the University of Arizona who did not participate
in the study. But he cautioned that researchers would want to see more direct
evidence of clay underneath Olympus Mons — perhaps from one of the Mars
orbiters currently eying the Red Planet.
The
European Space Agency's Mars Express spacecraft has in recent years found
abundant evidence of clay on Mars. This at least supports a previous theory
that where Olympus Mons now stands, a layer of sediment once rested that may
have been hundreds of meters thick.
What
may be trapped underneath is of great interest, said the researchers. Fluids
embedded in an impermeable, pressurized layer of clay sediment would allow the
kind of slipping motion that would account for Olympus Mons' spread-out
northeast flank — and may still exist in deep, trapped pockets within the
volcano.
"This
deep reservoir, warmed by geothermal gradients and magmatic heat and protected
from adverse surface conditions, would be a favored environment for the
development and maintenance of thermophilic organisms," McGovern and
Morgan write in this month's issue of the journal Geology.
Such
primal organisms already thrive deep in Earth's ocean near geothermal vents.
These and other seemingly extreme spots on Earth represent focal points for
intense biological activity, Farmer noted.
"Even
within an environment that might otherwise be rather dry, a point heat source
in contact with subsurface water or water ice can set up a convection system
that provides chemical nutrients to the near-surface environment, and maybe even
the surface," Farmer told SPACE.com.
Finding
a currently active source of heat represents one of the future challenges.
"We'd
love to have the answer to that question," McGovern said, noting evidence
of methane on Mars is considered by some to be another possible marker for
life. Spacecraft have yet to detect a true thermal event on Mars, such as a
magma flow or active volcano.
"What
we need is 'ground truth' — something reporting from the surface saying,
'Hey, there's a Marsquake,' or 'Hey, there's unusual emissions of gas,'"
McGovern added. "Ultimately, we'd like to see a series of seismic stations
so we can see what's moving around the planet."
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