There are no service stations on the surface of Mars, meaning any rover that suffers a component failure on the Red Planet will remain unrepaired. Curiosity has been exploring the surface of Mars for a long time, and mission controllers have a plan in place to help keep the rover mobile even if wheel wear becomes a problem. Should a wheel become damaged, JPL says that it is ready to use a “wheel shedding” maneuver to get rid of the defective wheel.
Curiosity has been exploring Mars since 2012, and JPL engineers have noticed wear on its wheels in the form of dense and small holes in the 0.75mm thick aluminum skin. Wear isn’t unexpected, but JPL scientists have noted that the wear is increasing faster than it had planned for.
By early 2017, the rover had experienced some breaks in the figure structure elements holding the wheels together, known as grousers. Each of the wheels fitted to the rover has 19 grousers and can remain functional with one or two broken. If enough of them break, the inside of the wheel could loosen and hit cabling connecting to the motor inside the wheel hub, opening the possibility of leaving the wheel inoperable or causing electrical damage that could leave the rover broken.
The JPL Wheel Wear Tiger Team looked at the problem and recommended where and how to drive to reduce wear rates on the wheels. It’s impossible to eliminate wear, so they also developed a backup plan if a wheel approaches catastrophic amounts of damage. That backup plan is to finding a sharp rock that can be used to rip out the insides of the wheel.
JPL notes that the skin of the wheels isn’t required for the wheel to be functional. The grousers keep the structure of the wheels stable. The wheels on the rover are currently completely functional despite modest damage. JPL says it would take 14 broken grousers on a single wheel before it would consider taking further action. Currently, the team believes it will be around 2034 before wear reaches significant levels.