My intent with this blog is to provide information about one of the best spy satellites ever flown by the United States. It was called Hexagon and flew between 1971 and 1986. It used film to capture images. The blog will include information about its development, technology and stories about some of the people involved. It will also include photographs that Hexagon took over the Soviet Union, and the United States. Most importantly it will explain how valuable it's photographs were to the US government security agencies in preserving the peace during the cold war. It turned out to become the most complicated satellite ever launched in space and when digital photography was introduced Hexagon became the last film based reconnaissance satellite.
My name is Phil Pressel and I worked as an engineer for the Perkin-Elmer Corporation in Danbury, Connecticut for 30 years. This is the company that was awarded a huge contract in 1966 by the CIA to design a brand new high-resolution orbiting spy satellite. It was called the Hexagon KH-9 system and was tasked to verify what our cold war enemies were doing with respect to military assets, as well as some other functions.
I was among several dozen people to initially work on a study to determine how feasible it was to come up with a system that met the CIA's requirements. These were to map the entire landmass of the earth and to take high-resolution photographs, in stereo, of military and other assets of our cold war enemies. I was given the job of being responsible for the design of the mechanical parts of its cameras. They were called, the optical bars. The satellite orbited the earth in a polar orbit with a perigee (closest to earth) of about 85 miles and an apogee (furthest from earth) of about 150 miles or more. As the earth turns from west to east and as the satellite orbited in a polar orbit (north to south and back) it was able to take photographs of the entire landmass of the earth.
The resulting photographs enabled the US to know what and where and how many missile launching sites or airplanes or other military assets the Soviet Union and others had. There were two cameras aboard the satellite because the CIA asked us to take photographs in stereo. One camera was aimed slightly forward and the other aimed slightly to the rear and thus the stereo capability enabled the photo-analysts to measure the height of ground objects. The advantage to future digital photography is that photos could be relayed to earth immediately while with film, the photos could only be seen after the film was returned to earth.
There were 4 re-entry vehicles (RV) on the satellite. Each RV contained two film take-up reels, one for each of the two cameras. When the reels in the first RV were full of film the RV was ejected and returned through the atmosphere, then a parachute deployed and was caught by a C-130 Air Force plane. Every few weeks or months as per each mission's requirements the RV's were returned. Missions lasted from 52 to 275 days. After all the film was used and the 4 RV's returned to earth the entire satellite was de-orbited and totally destroyed over the Pacific Ocean. Then the next satellite was launched from Vandenberg Air Force Base. In all there were 20 missions planned over a 15 year period.
The satellites' prime contractor was the Lockheed Corporation (before it became associated with the Martin Corporation) in Sunnyvale, California. Lockheed integrated the three major components of the satellite into the actual Lockheed designed vehicle. These were: the camera and film handling system by Perkin-Elmer, the Re-entry Vehicles by the McDonnell-Douglass Corporation and the film supplied by Kodak. The vehicle was 60 feet long (the length of a school bus), ten feet in diameter and weighted 30,000 pounds. It carried an incredible amount of film, namely up to 30 miles of film for each camera. The film was 0.002 inches thick or less, 6.6 inches wide and each 30 mile roll contained splices of black and white and color film. Both rolls of film were held in a large pressure enclosure. More later.