NASA's Mars
Reconnaissance Orbiter has officially completed it two-year primary mission of
examining Mars in unprecedented detail.
The
orbiter, set to continue observing the red planet for the next two years, has
returned 73 terabits of science data, more than all earlier Mars missions combined.
That data has revealed signs of a complex Martian history of climate change
that produced a diversity of past watery
environments.
Among the
major findings during MRO's primary
science phase was the revelation that the action of water on and near the
surface of Mars occurred for hundreds of millions of years.
The
spacecraft also observed that signatures of a variety of watery environments,
some acidic, some alkaline, increase the possibility that there are places on
Mars that could reveal evidence of past life, if it ever existed.
Since moving
into position 186 miles (300 km) above Mars' surface in October 2006, the
orbiter has imaged nearly 40 percent of the planet at a resolution that can
reveal house-sized objects in detail, and 1 percent in enough detail to see
desk-sized features.
The orbiter
also assembled nearly 700 daily global weather maps, dozens of atmospheric
temperature profiles, and hundreds of radar profiles of the subsurface and the
interior of the polar caps.
"These
observations are now at the level of detail necessary to test hypotheses about
when and where water has changed Mars and where future missions will be most
productive as they search for habitable regions on Mars," said Richard
Zurek, Mars Reconnaissance Orbiter project scientist at NASA's Jet Propulsion
Laboratory in Pasadena, Calif.
The Mars
Reconnaissance Orbiter has found repetitive layering in Mars' permanent polar
ice caps, which may record possible effects of cyclical changes in Mars' tilt
and orbit on global sunlight patterns.
Recent
climate cycles are indicated by radar detection of subsurface icy deposits outside
the polar regions, where near-surface ice is not permanently stable. Other
results reveal details of ancient streambeds, atmospheric hazes and motions of
water, along with the ever-changing weather on Mars.
MRO also
imaged its surface-bound teammates, including the Mars rover Opportunity poised
on the rim of Victoria Crater and NASA's Phoenix Mars Lander during
its descent earlier this year to the surface.
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