(Phys.org)—New research by Stanford aeronautics and astronautics Assistant Professor Sigrid Close suggests she's on track to solve a mystery that has long bedeviled space exploration: Why do satellites fail? In the popular imagination, satellites are imperiled by impacts from "space junk" – particles of man-made debris the size of a pea (or greater) that litter the Earth's upper atmosphere – or by large meteoroids like the one that recently exploded spectacularly over Chelyabinsk, Russia. Although such impacts are a serious concern, most satellites that have died in space haven't been knocked out by them. Something else has killed them. The likely culprit, it turns out, is material so tiny its nickname is "space dust."