Saturn (rocket family)

The SA-9 (Saturn I Block II), the eighth Saturn I flight, lifted off on February 16, 1965. This was the first Saturn with an operational payload, the Pegasus I meteoroid detection satellite.

The Saturn family of rockets were developed to launch heavy payloads to Earth orbit and beyond. They were adopted as the launch vehicles for the Apollo program. The two most important members of the family were the Saturn IB and the Saturn V.

Early development

The original Saturn design originated with a concept developed by Wernher von Braun in 1957. The rocket bore a striking resemblance of the German aggregate series A9-A12 (which were however never realized). He submitted a proposal to the United States Department of Defense, outlining a need to develop a heavy booster with thrust in the 1.5 million lbf (6.7 MN) range. Such a booster would be able to place a payload of 20,000 to 40,000 lb (10 to 20 t) in Earth orbit, or 6,000 to 12,000 lb (3 to 6 t) elsewhere in the Solar System. The following year, the Advanced Research Projects Agency (ARPA) approved a research and development program for a booster designated Juno V (as a continuation of the Juno I and Juno II series of rockets, the satellite-launching variants of the military Jupiter-C and Jupiter IRBM).

Two approaches were considered: the first used multiple engines to reach the 1.5 million lbf (6.7 MN) mark, the second used a single engine of far greater power than had ever been conceived up to that point. Both avenues were investigated by von Braun’s team.

It was suggested that the most practical way to build a multi-engined booster was to cluster existing rocket stages together —a strategy that skeptics dubbed "Cluster's Last Stand"— but which quickly proved feasible with the construction of a non-flying test stage. Von Braun had proposed a design where eight Redstone missile stages would be clustered around a single Jupiter missile stage. Each of these nine individual rockets would be fitted with an engine derived from the S-3D engine already being used on Thor and Jupiter missiles. Rocketdyne, the manufacturer of the S-3D, received a contract to upgrade the engine from 150,000 to 188,000 lbf (670 to 840 kN) thrust. The resulting engine was designated the H-1.

At the same time, Rocketdyne designed a single engine that would develop the combined thrust of the clustered H-1 engines, designating it the F-1.

In 1959, Von Braun suggested that the name of the booster should be changed to "Saturn", one step beyond Jupiter, and ARPA approved the change. At the same time the military decided it had no immediate use for such a heavy launch vehicle, and turned the project over to the newly-formed NASA. NASA was working on its own large booster design at the time, Nova, but decided to take a serious look at von Braun's work. In the meantime, von Braun's team turned their efforts to development of the upper stages for the booster.

Silverstein Committee

A government commission, the "Saturn Vehicle Evaluation Committee" (better known as the Silverstein Committee) was assembled to recommend specific directions that NASA could take with the program. The committee recommended the development of new, hydrogen-burning upper stages for the Saturn, and outlined eight different configurations for heavy-lift boosters ranging from very low-risk solutions making heavy use of existing technology to designs that relied on hardware that had not been developed yet, including the proposed new upper stage. The configurations were:

• Saturn A
  • A-1 - Saturn cluster lower stage, Titan second stage, and Centaur third stage
  • A-2 - Saturn cluster lower stage, proposed Jupiter cluster second stage, and Centaur third stage

• Saturn B
  • B-1 - Saturn cluster lower stage, proposed Titan cluster second stage, proposed S-IV third stage and Centaur fourth stage

• Saturn C
  • C-1 - Saturn cluster lower stage, proposed S-IV second stage
  • C-2 - Saturn cluster lower stage, proposed S-II second stage, and proposed S-IV third stage
  • C-3, C-4, and C-5 - all based on different variations of a new lower stage using F-1 engines, variations of proposed S-II second stages, and proposed S-IV third stages.

Contracts for the development of a new hydrogen-burning engine was given to Rocketdyne in 1960 and for the development of the Saturn IV stage to Douglas the same year.

Project Apollo

The challenge that President John F. Kennedy put to NASA in May 1961 to put an astronaut on the Moon by the end of the decade put a sudden new urgency on the Saturn program. That year saw a flurry of activity as different means of reaching the Moon were evaluated.

Both the Nova and Saturn were evaluated for the mission, both of which had similar overall designs and used many of the same components. However, it was judged that the Saturn would be easier to get into production, as many of the components were deliberately designed to be air-transportable. Nova would require new factories for all the major stages, and there were serious concerns that they could not be completed in time. Saturn required only one new factory, and was selected primarily for that reason.

The Saturn C-5, (later given the name Saturn V), the most powerful of the Silverstein Committee's configurations, was selected as the most suitable design. At this point, however, all three stages existed only on paper, and it was realised that it was very likely that the actual lunar spacecraft would be developed and ready for testing long before the booster. NASA therefore decided to also continue development of the C-1 (later Saturn I) as a test vehicle, since its lower stage was based on existing technology (Redstone and Jupiter tankage) and its upper stage was already in development.

Ultimately, the members of the Saturn family that made it to the launch pad were:

• Saturn I - ten rockets flown to evaluate the S-I and, in later flights, the S-IV stages.
• Saturn IB - 9 launches, a refined version of the Saturn I with a more powerful first stage (designated the S-IB) and using the Saturn V's S-IVB as a second stage. These carried the first crewed Apollo flights into orbit, and later provided the boosters for the Skylab and Apollo-Soyuz flights.
• Saturn V - 12 launches, the Moon rocket that carried Apollo astronauts to the Moon.
• Saturn INT-21 - 1 launch, used to place the Skylab space station in orbit.