| | Stars in the sky: The top secret URSALA, RAQUEL, and FARRAH satellites from the 1970s to the 21st century by Dwayne A. DayMonday, March 10, 2025 | |

| Twenty HEXAGON satellites were launched from California between 1971 and 1986, with one failure. HEXAGON was a big photo-reconnaissance satellite, but often carried Program 989 subsatellites that were deployed in orbit. (credit: Peter Hunter) |

In 1963, the Air Force launched the first “hitchhiker” off the side of a larger satellite. This began a secretive program that lasted more than 40 years under a variety of names and designations. The satellites, about the size of a large suitcase, were festooned with antennas and spun rapidly as they orbited the Earth, sweeping their antennas over the ground and gathering radar and other signals, so-called electronic intelligence, or ELINT. They usually recorded the signals for later transmission to the ground, but occasionally directly re-transmitted them to a ground station.