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Heavy Elint

Early Heavy ELINT Spacecraft Series

By © Charles P. Vick 2007 All Rights Reserved

06-(2)/ 10-03-07

Early Heavy ELINT Spacecraft Series – (Program AFP-102, 698, 706, 770)

Code name SXXXX and later versions were apparently code named SXXXXX the Heavy ELINT (electronics intelligence) spacecraft mark the departure to what was to evolve into the major SIGINT spacecraft used by the US intelligence Community. They were launched by the Thor Agena-B, Thor Agena-D, TAT Thor Agena-B, TAT Thor Agena-D and Thorad Agena-D series boosters with a total of at least 16 launch attempts with only one failure. The SXXXX series are believed to have been the Agena-B series while the SXXXXX series are believed to be the Agena-D based series. Both ELINT packages are believed to have been very compact satellites with very limited electro-magnetic spectrum frequency range receiving equipment. There may have been other flights in the series yet to be fully identified in the second series as well as in the CANYON and RHYOLITE series. That is that the subsequent SIGINT satellite series apparently flew much sooner than previously recognized. SXXXX’s first of sixteen launches took place February 21, 1962 and its last launch was July 16, 1971. The inclinations and orbital altitudes varied for their specific mission requirements as did also the mass of the spacecraft. The heavily instrumented radio emissions receiving packages went beyond the Agena deployed Ferret sub satellite SIGINT packages released during the KH-4A, KH-4B and KH-7 and later KH-9 missions. They were fully dedicated mission package operation that was highly successful in acquiring ELINT electronic intelligence before the advent of the subsequent larger multi-mission general SIGINT dishes.

The spacecraft were actually nothing more than military services specific sophisticated earth orbit space based earth receiving stations operating within certain frequency range monitoring designs to pick up the emitted electro-magnetic spectrum from the ground such as electronic signals (ELINT), radio communications intelligence (COMINT) and radar emissions (RADINT) in addition to the telemetry (TELINT) acquisitions capabilities all coming under the general SIGINT (signals intelligence) heading. Operating in relative low earth orbit over target area’s of interest for only a few minutes they apparently worked on a passive record data store information gathering and command dump operational mode. They were not as sophisticated as the follow on SIGINT dish spacecraft but for their era were quite remarkable for what was possible to obtain from the accumulated data gathered over many orbital passes and missions.

The technology for these SIGINT spacecraft were slow in coming on line development wise but later proved out highly successfully once the technology was perfected. Like any new technology program it had its issues that slowed its initial progress. During the era they were developed it literally became a serious chase to just keep up with the developing different kinds of electronic emissions that these systems were able to monitor crying for larger more sophisticated systems able to do multiple missions at the same time.

This compact five foot diameter Agena-B based spacecraft and later five foot diameter by 20.86 foot long Agena-D based spacecraft came in several variety packages which were logically designed to support individual military services such as the Navy, Air Force and NSA for the Army among others services. The Agena-B and later Agena-D rocket stage portion of the early Heavy ELINT packages carried the usual assortment of earth, horizon and solar sensors to orient the spacecraft nose downward to the Earth. The Agena’s presumably carried solar arrays for extended length missions even though the life of the systems was measured in days to as much as two weeks.


1. Pike, Christopher Anson, “CANYON, RHYOLITE and AQUACADE,” Spaceflight, Vol. 37, November 1995 pp. 381-383.

2. Dr. McDowell, Jonathan , U. S. Reconnaissance Satellites Programs, Part 2: Beyond Imaging, Quest, Vol. 4, No. 4.

3. Day, Dwayne A., Ferrets of the High Frontier, Spaceflight, Vol. 46, February 2004, pp. 75-81.

Two Week Long Ferret/SIGINT/Heavy ELINT Satellite Series

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Page last modified: 21-07-2011 13:04:27 ZULU