AEnginesNASASolid EnginesUnited StatesUpper Stage Antares Antares IIA X-259 at the Smithsonian Air & Space Museum The Antares Solid Rocket Motor was an upper stage engine that was used on the United States’ Scout launch vehicle. Antares IIA Technical Drawing [SC1]Antares IIA X-259 at the Smithsonian Air & Space MuseumAntares IIB Thrust Curve [SC1]Antares IIIA Technical Drawing [SC1]