Atlas-Agena was a family of expendable launch vehicles that paired Atlas-derived first stages with Lockheed Agena upper stages. Agena A served early Air Force payloads, while restartable Agena B and standardized Agena D supported NASA's Ranger, Mariner, OGO, Lunar Orbiter, Gemini target, astronomy, communications, and Earth-science missions. The family operated from 1960 through 1978.