NASA Research Offers New Prospect Of Water On Mars

WASHINGTON -- NASA scientists are seeing new evidence that suggests
traces of water on Mars are under a thin varnish of iron oxide, or
rust, similar to conditions found on desert rocks in California's Mojave Desert.

Mars could be spotted with many more patches of carbonates than
originally suspected. Carbonates are minerals that form readily in
large bodies of water and can point to a planet's wet history.
Although only a few small outcrops of carbonates have been detected
on Mars, scientists believe many more examples are blocked from view
by the rust. The findings appear in the Friday July 1, online edition
of the International Journal of Astrobiology.

"The plausibility of life on Mars depends on whether liquid water
dotted its landscape for thousands or millions of years," said Janice
Bishop, a planetary scientist at NASA's Ames Research Center at the
SETI Institute at Moffett Field, Calif., and the paper's lead author.
"It's possible that an important clue, the presence of carbonates,
has largely escaped the notice of investigators trying to learn if
liquid water once pooled on the Red Planet."

Scientists conduct field experiments in desert regions because the
extremely dry conditions are similar to Mars. Researchers realized
the importance of the varnish earlier this year when Bishop and Chris
McKay, a planetary scientist at Ames investigated carbonate rocks
coated with iron oxides collected in a location called Little Red
Hill in the Mojave Desert.

"When we examined the carbonate rocks in the lab, it became evident
that an iron oxide skin may be hindering the search for clues to the
Red Planet's hydrological history," McKay said. "We found that the
varnish both altered and partially masked the spectral signature of
the carbonates."

McKay also found dehydration-resistant blue-green algae under the rock
varnish. Scientists believe the varnish may have extended temporarily
the time that Mars was habitable, as the planet's surface slowly dried up.

"The organisms in the Mojave Desert are protected from deadly
ultraviolet light by the iron oxide coating," McKay said. "This
survival mechanism might have played a role if Mars once had life on
the surface."

In addition to being used to help characterize Mars' water history,
carbonate rocks also could be a good place to look for the signatures
of early life on the Red Planet. Every mineral is made up of atoms
that vibrate at specific frequencies to produce a unique fingerprint
that allows scientists to accurately identify its composition.

Research data were similar to observations provided by NASA's Mars
Reconnaissance Orbiter (MRO) spacecraft, as it orbited an ancient
region of Mars called Nili Fossae. The area revealed the strongest
carbonate signature ever found. Although MRO recently detected small
patches of carbonates, approximately 200-500 feet wide, on the
Martian surface, the Mojave study suggests more patches may have been
overlooked because their spectral signature could have been changed
by the pervasive varnish.

"To better determine the extent of carbonate deposits on Mars, and by
inference the ancient abundance of liquid water, we need to
investigate the spectral properties of carbonates mixed with other
minerals," Bishop said.

The varnish is so widespread that NASA's Mars Exploration Rovers,
Spirit and Opportunity, used a motorized grinding tool to remove the
rust-like overcoat on rocks before other instruments could inspect
them. In 2010, scientists using data collected by Spirit also
identified a small carbonate outcrop at a crater called Gusev. NASA's
newest and most capable rover, the Mars Science Laboratory Curiosity
is schedule to launch in November. It will use tools to study whether
the Mars had environmental conditions favorable for supporting
microbial life and favorable for preserving clues about whether life existed.

Launched in 2006, MRO observes Mars' surface, subsurface and
atmosphere in unprecedented detail. Opportunity and Spirit completed
their three-month prime missions on Mars in April 2004, but continued
to collect data. NASA ended operations for Spirit this year to focus
only on Opportunity activities. NASA's Jet Propulsion Laboratory in
Pasadena manages MRO, Mars rovers and Curiosity for NASA's Science
Mission Directorate in Washington. For more information about NASA's
Mars missions, visit:

http://www.nasa.gov/mars

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