Saturn V - Proposed Successors

Proposed Successors

U.S. proposals for a rocket larger than the Saturn V from the late 1950s through the early 1980s were generally called Nova. Over thirty different large rocket proposals carried the Nova name, but none were developed.

Wernher von Braun and others also had plans for a rocket that would have featured eight F-1 engines in its first stage allowing it to launch a manned spacecraft on a direct ascent flight to the Moon. Other plans for the Saturn V called for using a Centaur as an upper stage or adding strap-on boosters. These enhancements would have increased its ability to send large unmanned spacecraft to the outer planets or manned spacecraft to Mars.

In 2006, as part of the cancelled Constellation Program that would have replaced the Space Shuttle, NASA unveiled plans to construct the heavy-lift Ares V rocket, a Shuttle Derived Launch Vehicle using some existing Space Shuttle and Saturn V infrastructure. Named in homage of the Saturn V, the original design, based on the Space Shuttle External Tank, was 360 ft (110 m) tall, and powered by five Space Shuttle Main Engines (SSMEs) and two uprated five-segment Space Shuttle Solid Rocket Boosters, which a modified variation would be used for the crew-launched Ares I rocket. As the design evolved, the Ares V was slightly modified, with the same 33 ft (10 m) diameter as that of the Saturn V's S-IC and S-II stages, and in place of the five SSMEs, five RS-68 rocket engines, the same engines used on the Delta IV EELV, would be used. The switch from the SSME to the RS-68 was due to the steep price of the SSME, as that it would be thrown away along with the Ares V core stage after each use, while the RS-68 engine, which is expendable, is cheaper, simpler to manufacture, and more powerful than the SSME.

In 2008, NASA again redesigned the Ares V, lengthening and widening the core stage and added an extra RS-68 engine, giving the launch vehicle a total of six engines. The six RS-68B engines, during launch, would have been augmented by two "5.5-segment" SRBs instead of the original five-segment designs, although no decision was made on the number of segments NASA would have used on the final design. If the six RS-68B/5.5-segment SRB variant had been used, the vehicle would have had a total of approximately 8,900,000 lbf (40 MN) of thrust at liftoff, making it more powerful than the Saturn V or the Soviet/Russian Energia boosters, but less than 50–43 MN for the Soviet N-1. An upper stage, known as the Earth Departure Stage and based on the S-IVB, would have utilized a more advanced version of the J-2 engine known as the "J-2X," and would have placed the Altair lunar landing vehicle into a low earth orbit. At 381 ft (116 m) tall and with the capability of placing 180 tons into low Earth orbit, the Ares V would have surpassed the Saturn V and the two Soviet/Russian superboosters in both height, lift, and launch capability.

The RS-68B engines, based on the current RS-68 and RS-68A engines built by the Rocketdyne Division of Pratt and Whitney (formerly under the ownerships of Boeing and Rockwell International), produce less than half the thrust per engine as the Saturn V's F-1 engines, but are more efficient and can be throttled up or down, much like the SSMEs on the Shuttle. The J-2 engine used on the S-II and S-IVB would have been modified into the improved J-2X engine for use both on the Earth Departure Stage (EDS) as well as on the second stage of the proposed Ares I. Both the EDS and the Ares I second stage would have used a single J-2X motor, although the EDS was originally designed to use two motors until the redesign employing the five (later six) RS-68Bs in place of the five SSMEs.

In September 2011, NASA announced the Space Launch System (SLS) as the United States' new heavy-lift rocket for manned deep-space exploration, and which will be comparable in size and capabilities to the Saturn V. The new SLS has an upper-stage powered by a J2-X engine derived from the Saturn V launch vehicle, the first stage powered by five liquid-fueled rocket engines derived from the Space Shuttle's main engines, along with two strap-on SRBs also derived from the Shuttle program. The initial configuration of the new booster as proposed by NASA could lift approximately 70 metric tons to LEO, with later variants possibly lifting up to 130 metric tons.