Wheels of NASA’s Mars rover Curiosity has developed a few cracks or breaks which were observed during a routine check on March 19.
The previous check was carried out on January 27. NASA notes that the two new breaks were not observed during the check in January indicating that they developed after and were documented during the routine check on March 19. The mission’s first and second breaks in raised treads, called grousers, have developed on Curiosity’s left middle wheel and it is indicative of the continuous wear and tear that the rover is subjected to on Mars.
NASA assured that the rover and its wheels have enough lifespan still remaining for active operation on the Red Planet and while the breaks weren’t unexpected, they are an indication that the damage has started and that the left middle wheel is nearing a wheel-wear milestone.
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 wheel. The grousers bear much of the rover’s weight and provide most of the traction and ability to traverse over uneven terrain.
The mission team started monitoring the checking the wheels for damage after dents and holes were observed in the wheels much earlier 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.”
The rover is currently examining sand dunes partway up a geological unit called the Murray formation. As part of its drive, 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 environmental conditions 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.