[meteorite-list] Curiosity Mars Rover Crosses Rugged Plateau

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 27 Apr 2016 16:45:37 -0700 (PDT)
Message-ID: <201604272345.u3RNjb1N023530_at_zagami.jpl.nasa.gov>


Curiosity Mars Rover Crosses Rugged Plateau
Jet Propulsion Laboratory
April 27, 2016

NASA's Curiosity Mars rover has nearly finished crossing a stretch of
the most rugged and difficult-to-navigate terrain encountered during the
mission's 44 months on Mars.

The rover climbed onto the "Naukluft Plateau" of lower Mount Sharp in
early March after spending several weeks investigating sand dunes. The
plateau's sandstone bedrock has been carved by eons of wind erosion into
ridges and knobs. The path of about a quarter mile (400 meters) westward
across it is taking Curiosity toward smoother surfaces leading to geological
layers of scientific interest farther uphill.

The roughness of the terrain on the plateau raised concern that driving
on it could be especially damaging to Curiosity's wheels, as was terrain
Curiosity crossed before reaching the base of Mount Sharp. Holes and tears
in the rover's aluminum wheels became noticeable in 2013. The rover team
responded by adjusting the long-term traverse route, revising how local
terrain is assessed and refining how drives are planned. Extensive Earth-based
testing provided insight into wheel longevity.

The rover team closely monitors wear and tear on Curiosity's six wheels.
"We carefully inspect and trend the condition of the wheels," said Steve
Lee, Curiosity's deputy project manager at NASA's Jet Propulsion Laboratory,
Pasadena, California. "Cracks and punctures have been gradually accumulating
at the pace we anticipated, based on testing we performed at JPL. Given
our longevity projections, I am confident these wheels will get us to
the destinations on Mount Sharp that have been in our plans since before

Inspection of the wheels after crossing most of the Naukluft Plateau has
indicated that, while the terrain presented challenges for navigation,
driving across it did not accelerate damage to the wheels.

On Naukluft Plateau, the rover's Mast Camera has recorded some panoramic
scenes from the highest viewpoints Curiosity has reached since its August
2012 landing on the floor of Gale Crater on Mars. Examples are available
online at these sites:



The scenes show wind-sculpted textures in the sandstone bedrock close
to the rover, and Gale Crater's rim rising above the crater floor in the
distance. Mount Sharp stands in the middle of the crater, which is about
96 miles (154 kilometers) in diameter.

The next part of the rover's route will return to a type of lake-deposited
mudstone surface examined previously. Farther ahead on lower Mount Sharp
are three geological units that have been key destinations for the mission
since its landing site was selected. One of the units contains an iron-oxide
mineral called hematite, which was detected from orbit. Just above it
lies a band rich in clay minerals, then a series of layers that contain
sulfur-bearing minerals called sulfates. By examining them with Curiosity,
researchers hope to gain a better understanding of how long ancient environmental
conditions remained favorable for microbial life, if it was ever present
on Mars, before conditions became drier and less favorable.

Each of Curiosity's six wheels is about 20 inches (50 centimeters) in
diameter and 16 inches (40 centimeters) wide, milled out of solid aluminum.
Most of the wheel's circumference is a metallic skin that is about half
the thickness of a U.S. dime. Nineteen zigzag-shaped treads, called grousers,
extend about a quarter inch (three-fourths of a centimeter) outward from
the skin of each wheel. The grousers bear much of the rover's weight and
provide most of the traction and ability to traverse over uneven terrain.

The holes seen in the wheels so far perforate only the skin. Wheel-monitoring
images obtained every 547 yards (500 meters) have not yet shown any grouser
breaks on Curiosity. Earth-based testing examined long-term wear characteristics
and the amount of damage a rover wheel can sustain before losing its usefulness
for driving. The tests indicate that when three grousers on a wheel have
broken, that wheel has reached about 60 percent of its useful mileage.

At a current odometry of 7.9 miles (12.7 kilometers) since its August
2012 landing, Curiosity's wheels are projected to have more than enough
life remaining to investigate the hematite, clay and sulfate units ahead,
even in the unlikely case that up to three grousers break soon. The driving
distance to the start of the sulfate-rich layers is roughly 4.7 miles
(7.5 kilometers) from the rover's current location.

Curiosity reached the base of Mount Sharp in 2014 after fruitfully investigating
outcrops closer to its landing site and then trekking to the layered mountain.
For more information about Curiosity, visit:


News Media Contact

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
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

Received on Wed 27 Apr 2016 07:45:37 PM PDT

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