Space.com: Underground Plumbing System Discovered on Mars
skepticl1
By Ker Than
Staff Writer
posted: 15 February 2007
02:00 pm ET
A Mars-orbiting spacecraft has spotted a subterranean natural plumbing
system that might have ferried water beneath the surface of the red
planet in the distant past.
New images taken by the HiRISE camera on NASA's Mars Reconnaissance
Orbiter (MRO) show hills and plateaus with alternating layers of dark
and light colored rocks in Candor Chasma, one of several canyons that
make up Valles Marineris, a sprawling Martian rift valley that is
longer than the contiguous United States and up to seven times deeper
than the Grand Canyon in places.
Ancient Mars Plumbing (Check out this photo of Mars plumbing--Skeptic)
Cutting like a vertical scar across these light and dark bands in
Candor Chasma are a series of linear cracks surrounded by "halos" of
light-colored bedrock [image].
Also Today: Antarctica Hides Surprising Underground Plumbing System
Pipes in bedrock
In the Feb. 16 issue of the journal Science, University of Arizona
researchers Chris Okubo and Alfred McEwen argue that the halos are
proof that some form of fluid-either water, liquid carbon dioxide or a
combination of the two-once flowed through the bedrock.
The timing of the flow remains uncertain, the researchers say, and
could have occurred many millions or even billions of years ago.
They suggest that liquid flowing through the fractures deposited iron-
rich or clay-like minerals in the rock. The minerals would act like
cement to strengthen the layers of rock and also bleach it a lighter
color. Over millions of years, wind stripped away the top layers of
surface rock, exposing the subsurface and its plumbing system to the
light of day.
The linear cracks, called joints, are about a meter wide and range
from several hundred meters to several kilometers in length. How the
joints formed is still a mystery, but once formed, they would have
provided a conduit for flowing liquid, the researchers speculate.
"They acted sort of like pipes through the bedrock," Okubo told
SPACE.com.
Video: Life on Mars?
Earth analogy
Similar processes are known to occur on Earth. Veins of gold and
silver in rock, for example, are formed when water rich in the
dissolved forms of these elements flows through cracks and finally
deposit the metals as bright streaks in the rock.
Okubo says the new findings could have implications for life on Mars,
either in the distant past and perhaps even the present.
By being underground, the "fluid can remain in place for a longer
period of time," Okubo said. "That will allow for the geochemical
reactions to occur more thoroughly and more profusely through the
rock, perhaps giving rise to habitable oases within the protected
subsurface for any biologic activity to occur."
Philip Christensen, a leading Mars researcher at Arizona State
University, said the team's explanation for the joints is very
plausible, but points out that the liquid that once flowed through the
cracks might also have been volcanic magma.
Molten magma flows like liquid and can also alter the color of
surrounding rocks, Christensen said. It looks as if "fluid was
injected into these cracks. The question is what was the fluid? Was it
water or was it volcanic?"
Christensen added, however, that there are no large volcanoes in the
Candor Chasma region photographed by the MRO, so "water moving through
those fractures is probably more likely than volcanic material."
Image Gallery: Red Planet Revealed
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Volcanic Activity Brought Mars Water to Surface
Changing Mars Gullies Hint at Recent Flowing Water
All About Mars
http://www.space.com/scienceastronomy/070215_candor_chasma.html