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, and the Missile Detection Alarm System. 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.