One of the nation's primary aviation and aeronautics research and development facilities. Langley's 30 wind tunnels cover the entire speed range from 0 mph to nearly Mach 25 or orbital velocity (17,500 mph). In addition, Langley houses facilities for structures, materials and acoustics research; flight electronics; flight systems; simulation facility simulators; simulation facility components; and a scientific and general purpose computing complex. Occupies 787 acres and over 220 buildings, and shares some facilities with Langley Air Force Base, located adjacent to the Research Center. Employing over 4,000 people, NASA Langley has an annual budget around $600 million.