A piece of space junk the size of a school bus is barreling straight towards the moon

NPR spoke to John Crassidis about a school bus-sized piece of a rocket that’s hurtling toward the moon. While the impending collision isn’t cause for too much concern, Crassidis says it's possible that within 50 years, we get to the point where there's so much debris, we won't be able to launch any more satellites. "When objects start to collide with other objects, that's going to cause more debris ... and you get a cascading effect," he said, citing what's known as Kessler’s Syndrome. "That's a big concern."