Breaks observed in Mars rover wheel treads

March 22, 2017
Two of the raised treads, called grousers, on the left middle wheel of NASA's Curiosity Mars rover broke during the first quarter of 2017, including the one seen partially detached at the top of the wheel in this image from the Mars Hand Lens Imager (MAHLI) camera on the rover's arm. Credit: NASA/JPL-Caltech/MSSS

A routine check of the aluminum wheels on NASA's Curiosity Mars rover has found two small breaks on the rover's left middle wheel—the latest sign of wear and tear as the rover continues its journey, now approaching the 10-mile (16 kilometer) mark.

The mission's first and second breaks in raised treads, called grousers, appeared in a March 19 image check of the wheels, documenting that these breaks occurred after the last check, on Jan. 27.

"All six wheels have more than enough working lifespan remaining to get the vehicle to all destinations planned for the mission," said Curiosity Project Manager Jim Erickson at NASA's Jet Propulsion Laboratory, Pasadena, California. "While not unexpected, this damage is the first sign that the left middle wheel is nearing a wheel-wear milestone,"

The monitoring of wheel damage on Curiosity, plus a program of wheel-longevity testing on Earth, was initiated after dents and holes in the wheels were seen to be accumulating faster than anticipated in 2013. Testing showed that at the point when three grousers on a wheel have broken, that wheel has reached about 60 percent of its useful life. Curiosity already has driven well over that fraction of the total distance needed for reaching the key regions of scientific interest on Mars' Mount Sharp.

Curiosity Project Scientist Ashwin Vasavada, also at JPL, said, "This is an expected part of the life cycle of the wheels and at this point does not change our current science plans or diminish our chances of studying key transitions in mineralogy higher on Mount Sharp."

Curiosity is currently examining sand dunes partway up a geological unit called the Murray formation. Planned destinations ahead include the hematite-containing "Vera Rubin Ridge," a clay-containing geological unit above that ridge, and a sulfate-containing unit above the clay unit.

The rover is climbing to sequentially higher and younger layers of lower Mount Sharp to investigate how the region's ancient climate changed billions of years ago. Clues about environmental conditions are recorded in the rock layers. During its first year on Mars, the mission succeeded at its main goal by finding that the region once offered favorable for microbial life, if Mars has ever hosted life. The conditions in long-lived ancient freshwater Martian lake environments included all of the key chemical elements needed for life as we know it, plus a chemical source of energy that is used by many microbes on Earth.

Through March 20, Curiosity has driven 9.9 miles (16.0 kilometers) since the mission's August 2012 landing on Mars. Studying the transition to the sulfate unit, the farthest-uphill destination, will require about 3.7 miles (6 kilometers) or less of additional driving. For the past four years, rover drive planners have used enhanced methods of mapping potentially hazardous terrains to reduce the pace of damage from sharp, embedded rocks along the rover's route.

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. The wheels contact ground with a skin that's about half as thick as a U.S. dime, except at thicker treads. The grousers are 19 zigzag-shaped treads that extend about a quarter inch (three-fourths of a centimeter) outward from the skin of each . The grousers bear much of the rover's weight and provide most of the traction and ability to traverse over uneven terrain.

Explore further: Curiosity Mars rover crosses rugged plateau

Related Stories

Curiosity Mars rover crosses rugged plateau

April 28, 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.

Curiosity rover team examining new drill hiatus

December 6, 2016

NASA's Curiosity Mars rover is studying its surroundings and monitoring the environment, rather than driving or using its arm for science, while the rover team diagnoses an issue with a motor that moves the rover's drill.

Mars rover Curiosity views spectacular layered rock formations

September 10, 2016

The layered geologic past of Mars is revealed in stunning detail in new color images returned by NASA's Curiosity Mars rover, which is currently exploring the "Murray Buttes" region of lower Mount Sharp. The new images arguably ...

Curiosity rover begins next Mars chapter

October 3, 2016

After collecting drilled rock powder in arguably the most scenic landscape yet visited by a Mars rover, NASA's Curiosity mobile laboratory is driving toward uphill destinations as part of its two-year mission extension that ...

Recommended for you

Solar minimum surprisingly constant

November 17, 2017

Using more than a half-century of observations, Japanese astronomers have discovered that the microwaves coming from the sun at the minimums of the past five solar cycles have been the same each time, despite large differences ...

Lava or not, exoplanet 55 Cancri e likely to have atmosphere

November 16, 2017

Twice as big as Earth, the super-Earth 55 Cancri e was thought to have lava flows on its surface. The planet is so close to its star, the same side of the planet always faces the star, such that the planet has permanent day ...

SpaceX poised to launch secretive Zuma mission

November 16, 2017

SpaceX is poised to launch on Thursday a secretive payload known as Zuma for the US government, though the nature of the mission and the agency behind it remain a mystery.

7 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Moltvic
Mar 22, 2017
This comment has been removed by a moderator.
NoStrings
5 / 5 (1) Mar 22, 2017
Only 15 miles lifespan for the wheels? The mission weak point will be the wheels, about the simplest mechanical part.
Repurplecirculation
not rated yet Mar 22, 2017
I presume they are considering using different materials for the next generation of rovers. The daily expansion/contraction of thin aluminum clearly fatigues faster in this extreme environment. Perhaps one of these newer graphene compounds may work better. Don't know, but it will be interesting to see what the engineers pick.
gries1871
not rated yet Mar 23, 2017
should have made the wheels from titanium!!! NEVER aluminum....
RDS
not rated yet Mar 23, 2017
Should have gone with the mag wheel upgrade.
Lex Talonis
not rated yet Mar 25, 2017
No you dumb fucks...

The wheels are like big hard aluminium drums with a thin rubber like coating on them.

If you run over rocks with rigid sheet metal wheels, the rocks poke holes in them, and break them up....

Lex Talonis
1 / 5 (1) Mar 25, 2017
And the numb skull who wrote the article... "The Grousers" or the morons terminology for tread...

They DO NOT bear the vehicles weight - they are the skin on the rolling element, that carries the weight, they provide a huge increase in the available "traction" or grip, that smooth sheet metal wheels provide, when going up or down sandy / rocky slopes..

And the moron from NASA...

"The grousers are 19 zigzag-shaped treads that 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."

Thanks for the METRIC lesson too. ~1/4 of an inch is when coverted to metric is 25.4mm / 4 = 6.35mm and 3 three fourths off a centimeter is expressed as 7.5mm.

Murrica educates the world in Metric again.

And NASA officially converted everything - and it's suppliers, to Metric when?????

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.