Four
intriguing places on Mars have risen to the final round as NASA selects a
landing site for its next Mars mission, the Mars Science Laboratory.
Mars
Science Laboratory (MSL)
project leaders at NASA's Jet Propulsion Laboratory, Pasadena, Calif., chose the four this month, after seeking input from international Mars experts and
from engineers working on the landing system and rover capabilities to whittle
down the initial list of more than 30 sites.
The sites,
alphabetically, are: Eberswalde,
where an ancient river deposited a delta in a possible lake; Gale, with a
mountain of stacked layers including clays and sulfates; Holden, a crater
containing alluvial fans, flood deposits, possible lake beds and clay-rich
deposits; and Mawrth,
which shows exposed layers containing at least two types of clay.
Gale is
near the equator, Eberswalde and Holden are farther south, and Mawrth is in the
north.
"All
four of these sites would be great places to use our roving laboratory to study
the processes and history of early Martian environments and whether any of
these environments were capable of supporting microbial life and its
preservation as biosignatures," said MSL project scientist John Grotzinger
of Caltech.
The
mission's capabilities for landing more precisely than ever before and for
generating electricity without reliance on sunshine have made landing sites
eligible that would not have been acceptable for past Mars missions. During the
past two years, multiple
observations of dozens of candidate sites by NASA's Mars Reconnaissance
Orbiter have augmented data from earlier orbiters for evaluating sites'
scientific attractions and engineering risks.
JPL is
assembling and testing the Mars Science Laboratory spacecraft for launch in
fall 2009. The mission plan calls for the rover to spend a full Mars year (23
months) examining the environment with a diverse payload of tools.
After
evaluating additional Mars orbiter observations of the four sites, NASA will
hold a fourth science workshop about the candidates in the spring and plans to
choose a final site next summer.
One site,
Gale, had been
a favorite of scientists considering 2004 landing sites for NASA's Spirit
and Opportunity rovers, but was ruled out as too hazardous for the capabilities
of those spacecraft.
"Landing
on Mars always is a risky balance between science and engineering. The safest sites
are flat, but the spectacular geology is generally where there are ups and
downs, such as hills and canyons. That's why we have engineered this spacecraft
to make more sites qualify as safe," said JPL's Michael Watkins, mission
manager for MSL.
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