The Boeing B-52 Stratofortress has been operational with the United States Air Force since 1955. This list is of the units it was assigned to, and the bases it was stationed. In addition to the USAF, A single RB-52B (52-008) was flown by the National Aeronautics and Space Administration (NASA) until it was retired on 17 December 2004. It now is on static display at the west gate of Edwards AFB, California. One other B-52H (61-0025) was flown for many years by the Air Force Flight Test Center at Edwards, and was transferred to NASA on 30 July 2001 as a replacement for the RB-52B. On 9 May 2008, that aircraft was flown for the last time to Sheppard AFB, Texas where it became a GB-52H maintenance trainer, never to fly again.