[meteorite-list] NASA's Curiosity Mars Rover Heads Toward Active Dunes

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 17 Nov 2015 12:47:30 -0800 (PST)
Message-ID: <201511172047.tAHKlUj6018176_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?feature=4772

NASA's Curiosity Mars Rover Heads Toward Active Dunes
Jet Propulsion Laboratory
November 16, 2015

On its way to higher layers of the mountain where it is investigating
how Mars' environment changed billions of years ago, NASA's Curiosity
Mars rover will take advantage of a chance to study some modern Martian
activity at mobile sand dunes.

In the next few days, the rover will get its first close-up look at these
dark dunes, called the "Bagnold Dunes," which skirt the northwestern flank
of Mount Sharp. No Mars rover has previously visited a sand dune, as opposed
to smaller sand ripples or drifts. One dune Curiosity will investigate
is as tall as a two-story building and as broad as a football field. The
Bagnold Dunes are active: Images from orbit indicate some of them are
migrating as much as about 3 feet (1 meter) per Earth year. No active
dunes have been visited anywhere in the solar system besides Earth.

"We've planned investigations that will not only tell us about modern
dune activity on Mars but will also help us interpret the composition
of sandstone layers made from dunes that turned into rock long ago," said
Bethany Ehlmann of the California Institute of Technology and NASA's Jet
Propulsion Laboratory, both in Pasadena, California.

As of Monday, Nov. 16, Curiosity has about 200 yards or meters remaining
to drive before reaching "Dune 1." The rover is already monitoring the
area's wind direction and speed each day and taking progressively closer
images, as part of the dune research campaign. At the dune, it will use
its scoop to collect samples for the rover's internal laboratory instruments,
and it will use a wheel to scuff into the dune for comparison of the surface
to the interior.

Curiosity has driven about 1,033 feet (315 meters) in the past three weeks,
since departing an area where its drill sampled two rock targets just
18 days apart. The latest drilled sample, "Greenhorn," is the ninth since
Curiosity landed in 2012 and sixth since reaching Mount Sharp last year.
The mission is studying how Mars' ancient environment changed from wet
conditions favorable for microbial life to harsher, drier conditions.

Before Curiosity's landing, scientists used images from orbit to map the
landing region's terrain types in a grid of 140 square quadrants, each
about 0.9 mile (1.5 kilometers) wide. Curiosity entered its eighth quadrant
this month. It departed one called Arlee, after a geological district
in Montana, and drove into one called Windhoek, for a geological district
in Namibia. Throughout the mission, the rover team has informally named
Martian rocks, hills and other features for locations in the quadrant's
namesake area on Earth. There's a new twist for the Windhoek Quadrant:
scientists at the Geological Society of Namibia and at the Gobabeb Research
and Training Center in Namibia have provided the rover team with a list
of Namibian geological place names to use for features in this quadrant.
The Windhoek theme was chosen for this sand-dune-bearing quadrant because
studies of the Namib Desert have aided interpretation of dune and playa
environments on Mars.

What distinguishes actual dunes from windblown ripples of sand or dust,
like those found at several sites visited previously by Mars rovers, is
that dunes form a downwind face steep enough for sand to slide down. The
effect of wind on motion of individual particles in dunes has been studied
extensively on Earth, a field pioneered by British military engineer Ralph
Bagnold (1896-1990). Curiosity's campaign at the Martian dune field informally
named for him will be the first in-place study of dune activity on a planet
with lower gravity and less atmosphere.

Observations of the Bagnold Dunes with the Compact Reconnaissance Imaging
Spectrometer on NASA's Mars Reconnaissance Orbiter indicate that mineral
composition is not evenly distributed in the dunes. The same orbiter's
High Resolution Imaging Science Experiment has documented movement of
Bagnold Dunes.

"We will use Curiosity to learn whether the wind is actually sorting the
minerals in the dunes by how the wind transports particles of different
grain size," Ehlmann said.

As an example, the dunes contain olivine, a mineral in dark volcanic rock
that is one of the first altered into other minerals by water. If the
Bagnold campaign finds that other mineral grains are sorted away from
heavier olivine-rich grains by the wind's effects on dune sands, that
could help researchers evaluate to what extent low and high amounts of
olivine in some ancient sandstones could be caused by wind-sorting rather
than differences in alteration by water.

Ehlmann and Nathan Bridges of the Johns Hopkins University's Applied Physics
Laboratory, Laurel, Maryland, lead the Curiosity team's planning for the
dune campaign.

"These dunes have a different texture from dunes on Earth," Bridges said.
"The ripples on them are much larger than ripples on top of dunes on Earth,
and we don't know why. We have models based on the lower air pressure.
It takes a higher wind speed to get a particle moving. But now we'll have
the first opportunity to make detailed observations."

JPL, managed by Caltech for NASA, built Curiosity and manages the project
for NASA's Science Mission Directorate in Washington. For more information
about Curiosity, visit:

http://www.nasa.gov/msl

http://mars.jpl.nasa.gov/msl/

You can follow the mission on Facebook and Twitter at:

http://www.facebook.com/marscuriosity

http://www.twitter.com/marscuriosity


Media Contact

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

Dwayne Brown / Laurie Cantillo
NASA Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown at nasa.gov / laura.l.cantillo at nasa.gov

2015-351
Received on Tue 17 Nov 2015 03:47:30 PM PST