HEXAGON

In late 1963, the NRO authorized studies for concepts and design of a new wide-area photo-reconnaissance system as a follow-on to CORONA under the name S-2. Participants were Eastman Kodak and Itek. Shortly afterwards, in 1964, the CIA started a similar study program, named FULCRUM, with the companies Itek and Perkin-Elmer. This situation led to increasing rivalries and squabbles over responsibilities between the NRO and the CIA, which were eventually resolved by a deal in August 1965. The CIA would be responsible for the development of the primary photographic system (i.e. effectively FULCRUM), while the NRO would manage the vehicle platforms and overall system integration. In April 1966, the new program was initialliy named HELIX, but renamed to HEXAGON after a few weeks when it turned out, that HELIX had already been used for a different program. The unclassified numerical designator was Program 467, and the reconnaissance system was designated KH-9.

By 1967, the contractors for the HEXAGON subsystems had been selected: Perkin-Elmer for the sensor subsystem (i.e. the primary telescope and camera assembly), Lockheed for the basic satellite assembly, Itek for the stellar index camera and McDonnell for the reentry vehicle. The initial launch vehicle for HEXAGON was the Titan IIID, consisting of the two-stage Titan III core and two large solid-fueled strap-on boosters. The first mission was successfully launched on 15 June 1971. Various kinds of problems were encountered, the most severe of which was thermal control of the battery temperature. Nevertheless, all relevant subsystems could be tested, and 3 out of 4 RVs recovered. After 52 days in orbit, the satellite was actively deorbited over the Pacific Ocean (something, which would be done at the end of every HEXAGON mission).

Drawings: Guiseppe di Chiara, CC BY-SA 3.0

HEXAGON (KH-9)

The HEXAGON satellite had a total in-orbit length of about 17.9 m (58.7 ft), a diameter of 3 m (10 ft) and a mass of around 11000 kg (24200 lb). The aft section, ca. 2 m (6.5 ft) long, contained the Orbital Adjust Module and Reaction Control Module, which maintained the proper attitude for the photography mission, and handled orbital changes and adjustments as needed. The middle section housed the primary sensor system, consisting of two independent panoramic cameras for stereo photography, the film supply, and all associated control and support equipment. The best-case resolution of the KH-9 was 60 cm (2 ft) or better. The front section of the satellite contained four Mk.8 Reentry Vehicles and the associated film transport system. Electrical power was provided by two large solar panels attached to the rear of the vehicle, and rechargable batteries for operation while passing through the earth's shadow. As an optional asset, HEXAGON could be fitted with an additional mapping camera system at the front end of the satellite, together with its own dedicated Mk.5 Reentry Vehicle.

The initial flight's battery problems were fixed for flight #2, but that one suffered from a failure of one of the main cameras early in the mission, so that most of the photography was only monoscopic. On the other hand, all 4 RVs could be successfully recovered. Starting from flight 5 (Mission 1205) and continuing through Mission 1216, the satellites carried the optional mapping camera system, covering almost 100 million km² of the Earth's surface during these 12 flights, at a resolution of 6-9 m (20-30 ft). During the course of the 20 HEXAGON missions, the satellite went through several block upgrades, mainly improving the camera system and the film load-out. The gradual weight increase of these upgrades led to the use of the more powerful Titan 34D launcher for the last three missions.

Photo: National Museum of the USAF

HEXAGON (KH-9)

Overall, the HEXAGON program was very successful, with 19 missions flown between 1971 and June 1984. Only the very last flight, on 18 April 1986, failed spectacularly when the Titan 34D exploded shortly after lift-off. The longest duration of a HEXAGON flight was 275 days (Mission 1218), and of all the RVs only three were not recovered. HEXAGON provided wide-area "search" reconnaissance, while GAMBIT-3 continued to be used for very high-resolution target-specific photography.

Beginning in the 1970s, both HEXAGON and GAMBIT-3 were first supplemented, and eventually replaced, by a completely new multi-purpose electro-optical imaging satellite system named KENNEN/KH-11.

HEXAGON (KH-9) Launch List

• No.: Sequential flight number for the HEXAGON program
• Blk.: HEXAGON Block number
• Name: Unclassified name of the satellite. The OPS number ("OPS" standing for "Operations") is a random number given to all military-related satellite launches between 1963 and May 1984 (when "OPS" was replaced by a sequential "USA" number).
• Mission: Each KH-9 mission had a unique serial number in the 12xx range.
• COSPAR ID: International designation of the satellite; not applicable, if orbit was not reached
• Duration: Time in orbit, between launch and deorbiting of the satellite; the time with actual photo-reconnaissance work was shorter
• Launch Vehicle: Variant of Titan booster

HEXAGON (KH-9) launches

Main Sources

[1] David Baker: "US Spy Satellites", Haynes Publishing, 2016
[2] The HEXAGON Story, Center for the Study of National Reconnaissance Classics, NRO, 2012

Back to Directory of U.S. Military Rockets and Missiles, Appendix 3

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Last Updated: 23 June 2025