ATS-5, the last spacecraft in the Hughes/NASA ATS program, was launched August 12, 1969, in a near-perfect trajectory for insertion into synchronous orbit. Although injected successfully into orbit, the spacecraft's reverse spin (counterclockwise) prevented successful deployment of the 124 foot gravity gradient booms for the stabilization experiment. However nine of the other 13 experiments aboard the spacecraft returned useful data.

The Atlas-Centaur was a US expendable launch vehicle derived from the SM-65 Atlas D missile. Launches were conducted from Launch Complex 36 at the Cape Canaveral Air Force Station in Florida.

The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal Corps, the USAF was established as a separate branch of the United States Armed Forces in 1947 with the enactment of the National Security Act of 1947.