Billionaire entrepreneur Elon Musk couldn't resist showing off some of his new toys on Twitter yesterday. First up is the latest version of SpaceX's reusable Falcon 9R rocket, which is now fitted with a set of four independently-adjustable fins. Or, as Musk described them: real-life X-wings. The grid fins are designed to deploy only after takeoff, when they'll work together with thrusters to help the rocket maneuver itself into position for those spectacular vertical landings. Musk says the hypersonic grid fins are similar to a set used on a test earlier this year
