NASA Orbiter Transition & Retirement team member Tom Goebel monitors the installation of "rain covers" over space shuttle Enterprise’s vent door openings ahead of the expected rain at Washington Dulles International Airport, Saturday, April 21, 2012, in Sterling, Va. Enterprise, the first orbiter built for the Space Shuttle Program, was used primarily for ground and flight tests within the atmosphere. The initial testing period named Approach and Landing Test (ALT) included a flight on February 18, 1977 atop a Shuttle Carrier Aircraft (SCA) to measure structural loads and ground handling and braking characteristics of the mated system. Enterprise will go on permanent display at the Intrepid Sea Air and Space Museum in New York in June. Photo Credit: (NASA/Bill Ingalls)