A Better Way to Turn Solar Sails

Solar sails are space’s ultimate free ride, they get their propulsion from the Sun, so they don’t need to carry propellant, but they come with their own challenges. A sail has a large surface area but a low mass, which creates a huge moment of inertia and makes it difficult to control, especially with reaction wheels. A team of engineers have cracked it though with “smart mirrors” that can instantly switch their reflectivity on command, transforming sunlight from an unruly force into a precision steering tool.