Atlas SLV-3

The Atlas SLV-3 was an American expendable launch system derived from the SM-65D Atlas missile, built as a standardised replacement for the earlier Atlas launch vehicles. Until 1965 most Atlas space launchers were D-series missiles with custom changes for each mission. The SLV-3 instead used one standard configuration based on the Atlas D, differing only in the width of the top of the rocket according to the upper stage it carried. It had thicker tank walls to bear the weight of upper stages, upgraded engines, and none of the retrorockets and other hardware a missile needs. Although the main engines had more thrust, the vernier engines were slightly detuned to improve vacuum specific impulse. It flew with Agena upper stages, mostly for classified Department of Defense payloads such as KH-7 Gambit satellites, and carried the Augmented Target Docking Adapter for Gemini 9A in June 1966. Versions SLV-3A, SLV-3B, SLV-3C and SLV-3D covered longer tanks and the Atlas-Centaur boosters, and variants of the design flew until the legacy Atlas was retired in 2005.