The spacecraft for this venture would be tiny, wafer-thin devices loaded with microelectronics and weighing just a gram; they’d be affixed to sturdy, ultrathin sails of comparable mass. Conventional rockets would carry the miniature probes into Earth orbit, and a synchronized array of ground-based lasers would then focus its beams on individual sails, imparting enough force to accelerate each probe to 20 percent of the speed of light.
While the plan requires technology we still don’t have, Milner is personally donating $100 million to support the necessary research and development. Space buffs are thrilled, though Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics is more cautious. “Starshot may not get us to the stars,” he says, “but it should, at a minimum, help us develop technologies that will be useful in future space exploration.”