Scientists say new data may reveal evidence of Mars' past life
22/2/2005 17:18
A team of international researchers has analyzed data freshly gathered
by the Mars Express mission, and offered new insight into the mineral
composition of Mars, scientists said Monday.
This new research, published
online in the journal Science, points out promising places to search for
evidence of past life, according to John Mustard, an associate professor of
geological sciences at Brown University, who took part in the research.
Mars
Express, Europe's first mission to the Red Planet, has generated a slew of new
data about the mineral composition of the planet's dry, dramatic surface. In six
new papers, the international team revealed clues about the planet's past hidden
in the rock.
Mustard said this research shows areas that contain water or may
have otherwise been amenable to life forms millions of years ago.
"If you
want to resolve the big question about life on Mars, you want to go to the right
places and get samples," Mustard said in a press release. "The new research
tells us where some of those places may be."
Researchers found a diverse and
complex mix of surface materials: silicates, ices and frosts, and hydrated
minerals and sediments.
Some areas, such as Terra Meridiani where the US Mars
rover Opportunity now operates, were rich in acidic sulfates. Rocks in other
places, for example around the Syrtis Major volcanic plateau, were richer in
clay and hydrated minerals. These are more neutral in pH, and thus more likely
to support life.
They also found kieserite, gypsum and polyhydrated sulfates,
all sulfate minerals that contain water in their crystal structure, in canyons
and buttes around the planet.
This shows that water was common and widespread
during the first billion years of Mars' roughly 4.6-billion-year history. These
minerals were even found inside Valles Marineris, the largest canyon in the
solar system.
Moreover, researchers found the rock-forming mineral olivine as
well as low- and high-calcium pyroxene across the Mars surface. They expected to
find hydrated minerals in the northern lowlands because of a theory that an
ancient ocean once covered these rolling plains.
But data collected by OMEGA,
a spectrometer aboard Mars Express using visible and infrared light to map the
surface composition of the planet, showed that the northern lowlands are
composed of volcanic rock not altered by water, making the ocean theory less
likely.
Based on these findings, scientists said Syrtis Major, Valles
Marineris and Terra Meridiani would all be strong candidates for rock and soil
sampling for future Mars missions. They also designed a next-generation
spectrometer that will be on board the Mars Reconnaissance Orbiter, which NASA
plans to launch in August.
Xinhua
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