Skylab

In 1968, the Apollo Applications Program was created to look into science missions that could be performed with the surplus Apollo hardware. Much of the planning centered on the idea of a space station, which eventually spawned theSkylab program. Skylab was launched using a two-stage Saturn V, sometimes called a Saturn INT-21.[2] It was the only launch not directly related to the Apollo lunar landing program.

Originally it was planned to use a 'wet workshop' concept, with a rocket stage being launched into orbit by a Saturn 1B and its spent S-IVB outfitted in space, but this was abandoned for the 'dry workshop' concept: An S-IVB stage from a Saturn IB was converted into a space station on the ground and launched on a Saturn V. A backup, constructed from a Saturn V third stage, is now on display at the National Air and Space Museum.

Three crews lived aboard Skylab from May 25, 1973 to February 8, 1974, with Skylab remaining in orbit until July 11, 1979.

Proposed post-Apollo developments

The (canceled) second production run of Saturn Vs would very likely have used the F-1A engine in its first stage, providing a substantial performance boost.[16] Other likely changes would have been the removal of the fins (which turned out to provide little benefit when compared to their weight); a stretched S-IC first stage to support the more powerful F-1As; and uprated J-2s for the upper stages.

A number of alternate Saturn vehicles were proposed based on the Saturn V, ranging from the Saturn INT-20 with an S-IVB stage and interstage mounted directly onto an S-ICstage, through to the Saturn V-23(L)[17] which would not only have five F-1 engines in the first stage, but also four strap-on boosters with two F-1 engines each: giving a total of thirteen F-1 engines firing at launch.

The Space Shuttle was initially conceived of as a cargo transport to be used in concert with the Saturn V, even to the point that a "Saturn-Shuttle," using the current orbiter and external tank, but with the tank mounted on a modified, fly-back version of the S-IC, would be used to power the Shuttle during the first two minutes of flight, after which the S-IC would be jettisoned (which would then fly back to KSC for refurbishment) and the Space Shuttle Main Engines would then fire and place the orbiter into orbit. The Shuttle would handle space station logistics, while Saturn V would launch components. Lack of a second Saturn V production run killed this plan and has left the United States without a heavy-lift booster. Some in the U.S. space community have come to lament this situation, as continued production would have allowed theInternational Space Station, using a Skylab or Mir configuration with both U.S. and Russian docking ports, to have been lifted with just a handful of launches, with the "Saturn Shuttle" concept possibly eliminating the conditions that caused the Challenger Disaster in 1986.

The Saturn V would have been the prime launch vehicle for the canceled Voyager Mars probes, and was to have been the launch vehicle for the nuclear rocket stage RIFT test program and the later NERVA.

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, NASA, as part of the upcoming Constellation Program that would replace the Space Shuttle after 2010, 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 designed 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 cost 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, will be augmented by two "5.5-segment" SRBs instead of the original five-segment designs, although no decision has yet been made on the number of segments NASA would be using on the final design.[1] If the six RS-68B/5.5-segment SRB variant is used, the vehicle would have a total of approximately 8,900,000 lbf (39.6 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, will utilize a more advanced version of the J-2 engine known as the "J-2X," and will place the Altair lunar landing vehicle into a low earth orbit. At 381 ft (116 m) tall and with the capability of placing 180 tons[vague] into low Earth orbit, the Ares V will surpass 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 will be 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 use 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.