So here's the deal with this mission: it's called Starshot and it involves a mothership that orbits the Earth, housing a fleet of smaller spacecrafts (we're talking iPhone-sized, and weighing a few grams). The mothership deploys these crafts, one per day for hundreds of days. Once deployed, each craft and its reflective "sail" aligns itself with a giant Earth-based laser, and waits there in position until the laser beam is turned on.
Now for the really cool part. The laser beam would act as a powerful propeller and send the craft throttling toward Alpha Centauri at about one-fifth the speed of light, or roughly 100 million MPH. There's no telling what wild and crazy deep-space obstacles might wander into its path, but by sending hundreds out into the great beyond, the odds that at least one makes it all the way there unscathed are greatly improved.