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NASA Orbiter Reveals Details of a Wetter Mars

Written by thomas · Filed Under Aeronautics News 

October 28, 2008

thomas

WASHINGTON, Oct. 28 /PRNewswire-USNewswire/ — NASA’s Mars
Reconnaissance Orbiter has observed a new category of minerals spread
across large regions of Mars. This discovery suggests that liquid water
remained on the planet’s surface a billion years later than scientists
believed, and it played an important role in shaping the planet’s surface
and possibly hosting life.

Researchers examining data from the orbiter’s Compact Reconnaissance
Imaging Spectrometer for Mars have found evidence of hydrated silica,
commonly known as opal. The hydrated, or water-containing, mineral deposits
are telltale signs of where and when water was present on ancient Mars.

“This is an exciting discovery because it extends the time range for
liquid water on Mars, and the places where it might have supported life,”
said Scott Murchie, the spectrometer’s principal investigator at the Johns
Hopkins University Applied Physics Laboratory in Laurel, Md. “The
identification of opaline silica tells us that water may have existed as
recently as 2 billion years ago.”

Until now, only two major groups of hydrated minerals, phyllosilicates
and hydrated sulfates, had been observed by spacecraft orbiting Mars.
Clay-like phyllosilicates formed more than 3.5 billion years ago where
igneous rock came into long-term contact with water. During the next
several hundred million years, until approximately 3 billion years ago,
hydrated sulfates formed from the evaporation of salty and sometimes acidic
water.

The newly discovered opaline silicates are the youngest of the three
types of hydrated minerals. They formed where liquid water altered
materials created by volcanic activity or meteorite impact on the Martian
surface. One such location noted by scientists is the large Martian canyon
system called Valles Marineris.

“We see numerous outcrops of opal-like minerals, commonly in thin
layers extending for very long distances around the rim of Valles Marineris
and sometimes within the canyon system itself,” said Ralph Milliken of
NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

Milliken is lead author of an article in the November issue of
“Geology” that describes the identification of opaline silica. The study
reveals that the minerals, which also were recently found in Gusev Crater
by NASA’s Mars rover Spirit, are widespread and occur in relatively young
terrains.

In some locations, the orbiter’s spectrometer observed opaline silica
with iron sulfate minerals, either in or around dry river channels. This
indicates the acidic water remained on the Martian surface for an extended
period of time. Milliken and his colleagues believe that in these areas,
low-temperature acidic water was involved in forming the opal. In areas
where there is no clear evidence that the water was acidic, deposits may
have formed under a wide range of conditions.

“What’s important is that the longer liquid water existed on Mars, the
longer the window during which Mars may have supported life,” says
Milliken. “The opaline silica deposits would be good places to explore to
assess the potential for habitability on Mars, especially in these younger
terrains.”

The spectrometer collects 544 colors, or wavelengths, of reflected
sunlight to detect minerals on the surface of Mars. Its highest resolution
is about 20 times sharper than any previous look at the planet in
near-infrared wavelengths.

NASA’s Jet Propulsion Laboratory manages the Mars Reconnaissance
Orbiter mission for NASA’s Science Mission Directorate in Washington.
Lockheed Martin Space Systems, Denver, is the prime contractor for the
project and built the spacecraft. The Applied Physics Laboratory led the
effort to build the spectrometer and operates the instrument in
coordination with an international team of researchers from universities,
government and the private sec

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