After 25 years of drifting undetected in space, an experimental satellite that launched in 1974 has been found using tracking data from the U.S. Space Force.
The Infra-Red Calibration Balloon (S73-7) satellite started its journey into the great unknown after launching on April 10, 1974 through the United States Air Force's Space Test Program. It was originally contained in what was called "The Hexagon System" in which S73-7, the smaller satellite, was deployed from the larger KH-9 Hexagon once in space. S73-7 measured 26 inches wide (66 centimeters) and began its life heading into a 500 mile (800 kilometers) circular orbit.
