But learning to control the vehicle hasn’t been smooth sailing. Unfurled, the feather-weight sail (made from a material called Mylar) could cover a boxing ring, but all steering power originates from a loaf-of-bread-sized body stuck to the middle. At just 11 pounds, LightSail 2 boasts the best heft-to-size ratio and the quickest acceleration of any solar sail to date. But that superlative makes it cumbersome to control, and as any sailor knows, tight control is crucial to getting where you want to go. “There are aspects that are weirdly analogous to sailing a ship,” says Mansell, who became certified to sail terrestrial ships in 2018.