Preparations are under way at the the mate-demate device, or MDD, at the Shuttle Landing Facility at NASA’s Kennedy Space Center in Florida to lift space shuttle Discovery atop a Shuttle Carrier Aircraft, or SCA. The MDD is a large gantry-like steel structure used to hoist a shuttle off the ground and position it onto the back of an SCA. The SCA is a Boeing 747 jet, originally manufactured for commercial use, which was modified by NASA to transport the shuttles between destinations on Earth. Discovery’s new home will be the Smithsonian National Air and Space Museum's Steven F. Udvar-Hazy Center in Chantilly, Va.