solid-fuel first-stage rocket boosters that burn simultaneously with the liquid-fueled core stage. The solid rocket booster on Ares V was first envisioned as an improved version of the Space Shuttle Solid Rocket Booster, but with five or five and a half segments instead of the four segments used with the Space Shuttle. The liquid-fueled core stage was to be derived from the Space Shuttle external tank and was to use either five or six RS-68B engines attached to the bottom of a new 10 m diameter tank, or five SSMEs attached to the bottom of a stretched version of the Space Shuttle's 8.4 m external tank. It was to be fueled by liquid oxygen (LOX) and liquid hydrogen (LH2). The upper stage, derived from the S-IVB upper stage used on the Saturn IB and Saturn V rockets, was named the Earth Departure Stage (EDS). The EDS would be powered by an Apollo-derived J-2X rocket engine, which was also to be used on the liquid-fueled upper stage of the Ares I booster. The EDS was to be used to steer the Altair lunar lander into its initial low Earth "parking" orbit for later retrieval by the Orion spacecraft, and then would propel both the Altair and Orion to the Moon. The EDS could also have been used to take large payloads into low Earth orbit, along with placing large uncrewed spacecraft onto trajectories beyond the Earth-Moon system. The Ares V was designed to have a payload capacity of over 414,000 lb (188 metric tons) to Low Earth orbit (LEO), and 157,000 lb (71 metric tons) to the Moon. Upon completion the Ares V would be the most powerful rocket ever built, lifting more into orbit than even the American Saturn V, the failed Soviet N-1 for the canceled Soviet Moonshot, and the successful Soviet/Russian Energia booster developed for the Buran Shuttle. Besides its lunar role, it could also support a crewed Orion expedition to a Near-Earth asteroid, and could boost an 8 to 16-meter successor of the Hubble Space Telescope to the Sun-Earth point. Derivatives Ares IV The Ares IV concept combines an Ares I upper stage on top of an Ares V. Specifically, the vehicle would consist of the liquid-fueled core stage from the Ares V design, two five-segment solid rocket boosters, and the liquid-fueled upper stage from the Ares I, as described by NASA in January 2007. The Ares