KH-8 Gambit-3 (Dual mode, Higherboy)

KH-8 Block 4 [NRO]
KH-8 Gambit-3 (Dual mode) similar

KH-8 Dual mode was a modification of the KH-8 Gambit-3 reconnaissance satellite, which was produced in the early 70ies as a fall-back measure against delay of the area surveillance KH-9 Hexagon satellite. It was also called Higherboy or Highboy.

The spacecraft was built, but placed into storage when the KH-9 succeeded. Eventually it was launched on 21. January 1982 on a Titan-3(24)B Agena-D booster into an orbit with a much higher apogee than the KH-8 satellites.

One of the two reentry vehicles failed to return to earth properly.

This launch represented a mystery over several years and was mostly attributed to a test flight of the project Indigo radar satellite, which in fact never happened. Also still unclear is the nature of the four objects, which appeared also on orbit, where the standard KH-8 did not produce this kind of objects. Possibly these were associated with the failed return vehicle.