It’s tough being a robot trekking along the dry, arid terrain of another planet with no humans around. NASA’s Curiosity rover has spent the past 13 years drilling through samples on Mars, and one rock decided to strike back. Curiosity recently got a rock stuck to its robotic arm while collecting samples from the Red Planet. NASA released a series of images that captured the grueling process of one robot trying to shake off a stubborn rock before finally breaking free. Work hazard NASA’s six-wheeled rover landed on Mars on August 5, 2012 , and has been exploring the Red Planet ever since to gather clues on Mars’ potentially habitable past. Curiosity’s robotic arm is equipped with a 6-pound (2.7 kilogram) drill designed to probe Martian rocks to collect and store samples. On August 25, the rover was drilling a sample from a rock nicknamed Atacama. This rock measures around 1.5 feet wide (0.4 meters) at its base, 6 inches thick (15 centimeters), and weighs roughly 28.6 pounds (13 kilograms), according to NASA.…