The 29-pound rock didn’t budge for almost a week. You know the feeling, you’re exploring an alien planet and drill into a rock, but the rock clings onto you and won’t let go. You wave your arms around in a desperate bid to shake it off. Actually, you probably don’t know that, but the Mars Curiosity Rover does after a rock estimated to be 1.5 feet in diameter and weighing 28.6 pounds (13 kilograms) got stuck on its drill. Curiosity was trying to get a sample. But got more than it bargained for when it lifted the entire rock from the surface. Then couldn’t get rid of it. Day turned to night, and still the rock clung on. Another angle. It would be easy to fix on Earth, but Curiosity is 140 million miles from home, and radio signals can take 30 minutes to travel between planets. It meant the stuck rock, which has been nicknamed “Atacama”, took a week to sort out.…