Orbiting Vehicle 2-5 (COSPAR ID: 1968-081A, also known as OV2-5), the third and last satellite of the second series of the United States Air Force's Orbiting Vehicle program, was an American particle science and ionosphere research satellite. Launched 26 September 1968 along with three other satellites, OV2-5 became the first scientific satellite to operate at geosynchronous altitude.