It's as if we took a trip into space with our best friends, and they turned into mutants and attacked us. Electrons are the best friends we've ever had from the subatomic world. We harness their flow as electricity to power all of modern life -- everything from cell phones and laptops to light bulbs. In space, however, electrons can turn against us. Boosted to almost the speed of light, "killer electrons" can knock out computers, pierce spacesuits, and damage the tissues of astronauts. New research using NASA's STEREO spacecraft is discovering exactly how this happens.