KH-9 Hexagon

KH-9 (BYEMAN codename HEXAGON), commonly known as Big Bird or Keyhole-9, was a series of photographic reconnaissance satellites launched by the United States between 1971 and 1986. Of twenty launch attempts by the National Reconnaissance Office, all but one were successful. Photographic film aboard the KH-9 was sent back to Earth in recoverable film return capsules for processing and interpretation. The best ground resolution achieved by the main cameras was better than 0.6 meters.

They are also officially known as the Broad Coverage Photo Reconnaissance satellites (Code 467), built by Lockheed Corporation for the National Reconnaissance Office.

The KH-9 was declassified in September 2011 and an example was put on public display, for one day, on September 17, 2011, in the parking lot of the Steven F. Udvar-Hazy Center of the National Air and Space Museum, outside Dulles International Airport.

On January 26, 2012 the National Museum of the United States Air Force put a KH-9 on public display along with its predecessors the KH-7 and KH-8.

The KH-9 was originally conceived in the early 1960s as a replacement for the Corona search satellites. The goal was to search large areas of the earth with a medium resolution camera. The KH-9 carried two main cameras, although a mapping camera was also carried on several missions. The photographic film from the cameras was sent to recoverable re-entry vehicles and returned to Earth, where the capsules were caught in mid-air by an aircraft. Four re-entry vehicles were carried on most missions, with a fifth added for missions that included a mapping camera.

...
Wikipedia