* Astronomy

The KH-11 KENNAN (KENNEN according to other sources), renamed CRYSTAL in 1982 and also referenced by the codenames 1010, and "Key Hole"), is a type of reconnaissance satellite launched by the American National Reconnaissance Office since December 1976. Manufactured by Lockheed in Sunnyvale, California, the KH-11 was the first American spy satellite to utilise electro-optical digital imaging, and create a real-time optical observation capability.
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Four generations of U.S. electro-optical reconnaissance have been identified:

Block I

Block I refers to the original KH-11 satellite, of which five were launched between 19 December 1976 and 17 November 1982.

Block II

The three Block II satellites are in the open literature referred to as KH-11B, the alleged DRAGON codename, or Crystal, and are believed to be capable of taking infrared images in addition to optical observations. The first and/or second Block II satellite was lost in a launch failure. On August 28, 1985 a Titan 34D boosting a KH-11 imagery satellite for NRO failed at the Vandenberg Air Force Base launch site.  Hubble is likely a Block II version satellite.

Block III

Four Block III satellites, commonly called KH-12 or Improved Crystal were launched between November 1992 and October 2001. The name "Improved Crystal" refers to the "Improved Metric CRYSTAL System" (IMCS), which adds reference markings for accurate mapping to images obtained by the satellite.

Block IV

Two electro-optical satellites launched in October 2005 and January 2011 are attributed to Block IV.