Since August of 2012, NASA's Curiosity Rover has tooled around the red planet doing science for us Earthlings. Now, nearly five years and some 10 miles later, the robot is starting to experience the wear and tear of an aging machine: On Tuesday, NASA announced the first two breaks in the rover's wheel treads.
Curiosity has a set of six aluminum wheels, each of them 20 inches in diameter and 16 inches across. The new breaks were the first to damage some of the 19 zigzag-shaped grousers (or threads) that cover each wheel. The grousers extend from the rest of the wheel (which is about half as thick as a dime) by about a quarter inch, allowing Curiosity to balance its 1,982 pounds of weight and grip the Martian terrain.
This isn't surprising—or even particularly upsetting—news, no matter how much you love NASA's youngest Martian robot. It may seem strange for there to be wear and tear with just 10 miles, but it took quite a few years to rack up those miles and all of that super-slow rolling over rocky terrain is just bound to cause some damage. Curiosity has already lived twice as long as planned in its primary mission. And NASA scientists have been keeping an eye on the rover's aging wheels for awhile now. These might be the first breaks in the grousers that give Curiosity traction, but they certainly aren't the first markups on otherwise pristine wheels: The reason NASA is keeping such a close eye on the wheels is that sharp rocks and grit have already left them pock-marked.
Curiosity may have outlived its initial mission, but it's got nothing on its big sister Opportunity, which has already exceeded its expected shelf-life by almost 13 years (and completed the equivalent of one very slow marathon). So one wonders: what's the prognosis for Curiosity?
According to on-Earth wheel longevity testing, NASA believes that "when three grousers on a wheel have broken, that wheel has reached about 60 percent of its useful life". The two grousers that broke sometime between January and March are both on the left middle wheel, so that guy is a hope and a prayer away from being more than halfway through its lifespan.
That...is not bad. Yes, one of the robot's wheels is now close to reaching a milestone we wish it never had to reach. But even if it hit that old-age benchmark tomorrow, the outlook would still be good: Curiosity is currently climbing up Mount Sharp to study Martian climate records trapped inside layers of rock, and has its sights set on areas thought to contain chemically interesting things like sulfates and clays—areas that might show evidence of past or present liquid water. But getting to those new targets will put less than five miles on its odometer.
"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 Project Scientist Ashwin Vasavada said in a statement.
Still, it's miserable being reminded that two favorite space robots can't live forever. Gather ye rosebuds while ye may, Curiosity, and fire that space laser of yours at will.