In 1989, two MIT artificial intelligence researchers made a terrifying prediction. "Within a few years," wrote Rodney Brooks and Anita Flynn, "it will be possible at modest cost to invade a planet with millions of tiny robots." Their paper "Fast, Cheap and out of Control: A Robot Invasion of the Solar System,", argued that small, autonomous "gnat robots" would soon become cheap enough to solve problems en masse. Nearly three decades later, those millions of tiny robots have yet to take over, at least not exactly like Brooks and Flynn envisioned. While they were right in some ways--the world has more than 700 million active iPhones--the vision of the fast, autonomous, tiny, buzzing bot is still a dream.