[meteorite-list] Curiosity Mars Rover Crosses Rugged Plateau

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=6452

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 
landing."

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:

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA20332

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA20333

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:

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


News 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 

2016-115