[meteorite-list] Site List Narrows For NASA's Next Mars Landing (MSL)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 19 Nov 2008 16:32:51 -0800 (PST)
Message-ID: <200811200032.QAA19715_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2008-219

Site List Narrows For NASA's Next Mars Landing
Jet Propulsion Laboratory
November 19, 2008

PASADENA, Calif. -- 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.

The agency had a wider range of possible landing sites to choose from
than for any previous mission, thanks to the Mars Science Laboratory's
advanced technologies, and the highly capable orbiters helping this
mission identify scientifically compelling places to explore.

Mars Science Laboratory 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.

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.

"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
John Grotzinger of the California Institute of Technology, Pasadena. He
is the project scientist for the Mars Science Laboratory.

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. Paring the landing-site list to four finalists
allows the team to focus further on evaluating the sites and planning
the navigation. 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. Three previous
landing-site science workshops for Mars Science Laboratory, in 2006,
2007 and two months ago, drew participation of more than 100 Mars
scientists and presentations about more than 30 sites. The four sites
rated highest by participants in the latest workshop were the same ones
chosen by mission leaders after a subsequent round of safety evaluations
and analysis of terrain for rover driving. 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 the Mars
Science Laboratory. "This will be the first spacecraft that can adjust
its course as it descends through the Martian atmosphere, responding to
variability in the atmosphere. This ability to land in much smaller
areas than previous missions, plus capabilities to land at higher
elevations and drive farther, allows us consider more places the
scientists want to explore."

For their Mars landings in 2004, Spirit and Opportunity needed safe
target areas about 70 kilometers (about 40 miles) long. Mars Science
Laboratory is designed to hit a target area roughly 20 kilometers (12
miles) in diameter. Also, a new "skycrane" technology to lower the rover
on a tether for the final touchdown can accommodate more slope than the
airbag method used for Spirit and Opportunity. In addition, a
radioisotope power supply, like that used by Mars Viking landers in the
1970s, will enable year-round operation farther from the equator than
the solar power systems of more recent missions.

Gale is near the equator, Eberswalde and Holden are farther south, and
Mawrth is in the north.

As a clay-bearing site where a river once flowed into a lake, Eberswalde
Crater offers a chance to use knowledge that oil industry geologists
have accumulated about locations of the most promising parts of a delta
to look for any concentrations of carbon chemistry that is crucial to life.

The mountain inside Gale Crater could provide a route for the rover to
drive up a 5-kilometer (3-mile) sequence of layers, studying a
transition from environments that produced clay deposits near the bottom
to later environments that produced sulfate deposits partway up.

Running water once carved gullies and deposited sediments as alluvial
fans and catastrophic flood deposits in Holden Crater, a site that may
also present the chance to evaluate layers deposited in a lake.
Exploration of key features within this target area would require drives
to the edge of a broad valley, and then down into the valley.

Mawrth Valley is an apparent flood channel near the edge of vast Martian
highlands. It holds different types of clays in clearly layered context,
offering an opportunity for studying the changes in wet conditions that
produced or altered the clays. The clay signatures are stronger than at
the other sites, and this is the only one of the four for which the
science target is within the landing area, not nearby.

JPL, a division of the California Institute of Technology, Pasadena,
manages the Mars Science Laboratory for the NASA Science Mission
Directorate, Washington. For additional information about the mission,
see http://mars.jpl.nasa.gov/msl.

Media contact: Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster at jpl.nasa.gov

2008-219
Received on Wed 19 Nov 2008 07:32:51 PM PST