1970's conceptual design of ion upper stage sized for use in the shuttle. It was nuclear-electric and intended for trans-Jovian planetary missions

Unit Cost $: 49.010 million. Length: 18.00 m (59.00 ft). Basic Diameter: 4.40 m (14.40 ft). Span: 4.40 m (14.40 ft). Mass: 15,627 kg (34,451 lb). Main Engine: Ion. Main Engine Thrust: 274 N (61 lbf). Main Engine Propellants: Electric/Mercury. Main Engine Propellants: 10,129 kg (22,330 lb). Main Engine Isp: 5,300 sec.