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SAMOS-A Pioneer

Military satellite projects were added to the mission of the Western Development Division in the mid-1950's and came to play an increasingly important role in the activities of the division's successors. The first satellite program was known as the Military Satellite System (WS 117L), and the division was given responsibility for it in February 1956. WS 117L was to be a family of separate subsystems that could carry out different missions, including photo reconnaissance and missile warning. By the end of 1959, WS 117L had evolved into three separate programs: the Discoverer Program, the Satellite and Missile Observation System (SAMOS)*, and the Missile Detection Alarm System (MIDAS). Discoverer and SAMOS were to carry out the photo reconnaissance mission, and MIDAS was to carry out the missile warning mission.

SAMOS, the second program that evolved from WS 117L, aimed at developing a heavier reconnaissance satellite that would be launched by an Atlas booster instead of the Thor used to launch the Discoverer. SAMOS had two launches – one in October 1960, which failed, and one in January 1961, which was successful. In 1962, a veil of secrecy was drawn across the SAMOS program, and the Air Force stopped releasing information about it. Unlike Discoverer, it has never been declassified.

* An interesting note on the project name is presented on page 44 of James Richelson's excellent book "America's Secret Eyes in Space" (Harper and Row, 1990).

"It has generally been observed that SAMOS was an acronym for Satellite and Missile Observation System. In fact, the name SAMOS was chosen by 117L Project Director Col. Fritz Oder in the belief that no one could produce an acroynm from it. Noting that MIDAS had already been selected as the name for the early warning satellite he noted that MIDAS lived on the isle of SAMOS. It was not long before the press started reporting SAMOS as an acronym."



By © Charles P. Vick 2007 All Rights Reserved

07-10-11 , 07

PIONEER/SAMOS-A –RECSAT, SIGINT Spacecraft Series – (USAF-Program AFP-101, 101A) E-1, E-2 Series

Code name PIONEER/SAMOS-A was the USAF failed first attempt at developing a near-real-time radio-transmission of space developed exposed film read-out imaging system. It was hoped that this series of earth orbit USAF, RECSAT, reconnaissance and SIGINT (signals intelligence) spacecraft would be used by the USAF and intelligence Community for primary imaging and SIGINT missions. They were launched by the stretched Atlas Agena-A and Atlas Agena-B series of booster launch vehicles with a total of six launches three of which failed. The first launch of this version of the Atlas Agena-A which failed carrying the E-1 payload, was lost on October 11, 1960. It was followed by the second and last Samos-2 Atlas Agena-A E-1 payload that did successfully orbit the spacecraft. This was the only mission to successfully return file that was of poor quality. The next two Atlas Agena-B missions with the Program 101A, E-2 payload failed but were followed by the successful orbiting missions. The last launch on an Atlas Agena-B carrying the Samos-6 with an E-2 payload was on March 7, 1962. The spacecraft were actually nothing more than USAF services specific earth orbit space based earth imaging spacecraft with a small SIGINT specific mission package. In all cases the last two missions failed to return usable film. The program was subsequently cancelled in late 1961 early 1962. This ended the development of the near-real-time radio-transmission of space developed exposed film read-out imaging system.


 1. McDowell, Jonathan, U. S. Reconnaissance Satellites Programs, Part 1: Photoreconnaissance, Quest, Vol. 4, No. 2, Summer 1995, pp.22-33.

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

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

4. Day, Dr. Dwayne A., Tinker Tailor, Radar, Spy, Early American Ferret and Radar Satellites, Spaceflight, Vol. 43, July 2001pp. 288-293.

5. Day, Dwayne A., A Failed Phoenix : The KH-6 LANYARD Reconnaissance Satellites, Spaceflight, Vol. 39, May 1997, pp. 170-174.

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