A long-lost experimental satellite launched in 1974 has been rediscovered by the U.S. Space Force, 25 years after it disappeared. The Infra-Red Calibration Balloon (S73-7) satellite was found using tracking data, after it had been missing for decades. The satellite was originally deployed from a larger satellite and was intended to serve as a calibration target, but failed to do so. It then drifted off into space and became part of the large amount of space junk orbiting Earth.