PHOTOS: When Discovery News Met Mars Rover ‘Curiosity'
"The wear in the wheels is expected," Matt Heverly, lead rover driver for the MSL mission at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., told Discovery News via email. "The ‘skin' of the wheel is only 0.75mm thick and we expect dents, dings, and even a few holes due to the wheels interacting with the rocks."
Curiosity's wheels are constructed from tough aircraft-grade aluminum, but they will certainly bear the brunt of rock attrition as the mission progresses.
Back on Earth, JPL scientists carry out test runs on Curiosity's skinny "twin" rover. The "Scarecrow," as its lovingly called, carries the same weight that Curiosity carries on Mars. Keep in mind that Mars gravity is roughly one-third of that on Earth, so the Scarecrow looks very spidery and small compared to its Martian sibling.
"We have the same wheels on our Scarecrow test rover, which weighs the same on Earth as Curiosity weighs on Mars," Heverly added. "We have driven Scarecrow about 12 kilometers (7.5 miles) in the Marsyard over rocks and slopes much harsher than we expect for Curiosity.
"There are some dents and holes in these wheels, but the rover is still performing well."
As seen in the inset image above, a closeup section of the inner edge of Curiosity's front left wheel not only has obvious denting, there may also be the beginnings of punctures in the aluminum skin. It may seem alarming, but it is an expected consequence of roving on Mars.
PHOTOS: Mars Rover's ‘Twin' Dominates Mojave Desert
"We will continue to characterize the wheels both on Mars and in the Marsyard, but we don't expect the wear to impact our ability to get to Mt. Sharp," said Heverly.
The top photograph was captured by Curiosity's Mars Hand Lens Imager (MAHLI), a camera mounted on its robotic arm, on sol 275 of the mission to Gale Crater. Periodically, MSL rover drivers command the camera to survey the rover's undercarriage and wheels to look for damage. The famous "self portraits" are used for the same reason - to make sure the rover is fully intact and to monitor dust build-up.
So, when looking closely at the wonderful array of imagery being beamed back from Mars, keep in mind that Curiosity's big wheels were designed to dominate Mars, but don't be surprised if they pick up some battle scars on the way.
The full set of MAHLI photos of Curiosity's wheels can be viewed in the mission's raw image archive.
Special thanks to JPL's Guy Webster and Whitney Clavin Image credits: NASA/JPL-Caltech