Thor-Delta Launch Vehicle

Thor-Delta was the original three-stage Delta launch-vehicle configuration. It combined a Douglas Thor DM-19 first stage with liquid-propellant Delta and solid-propellant Altair upper stages. Twelve vehicles flew for NASA from May 1960 through September 1962; the first launch failed after a second-stage malfunction, and the following eleven successfully launched pioneering communications, weather, astronomy, and space-science spacecraft.