The Curiosity rover's wheels after 10 years on the rugged Martian terrain.
Curiosity has 6 wheels, each about 20 inches (50 centimetres) in diameter. The wheels are made of aluminium and have cleats for traction and curved titanium spokes for springy support. This thin and unique design helps the rover move over rocks and sandy surfaces, while the flexible spokes minimize damage from the rugged landscape.
An interesting aspect of Curiosity's wheels is the special pattern of holes they have. As the rover moves, these holes imprint a pattern on the Martian surface, spelling out "JPL" (Jet Propulsion Laboratory) in Morse code, the NASA centre responsible for the rover.