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

[Ron Baalke]

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