Saturn rockets Summary

  • Last updated on November 10, 2022

A family of heavy-lift rockets that culminated with the Saturn V Moon rocket used in the Apollo Program.

History

In the late 1950’s, adaptations of existing intercontinental ballistic missile (ICBM) technology led to the development of the Atlas and Thor missiles and the Juno and Jupiter rockets. These rockets could be adapted to launch small payloads into Earth orbit, as demonstrated when a Jupiter C rocket developed by rocketry pioneer Wernher von Braun at the U.S. Army Ballistic Missile Agency (ABMA) successfully launched the United States’ first Earth-orbiting satellite, Explorer 1, on January 31, 1958.

Even before Explorer 1 was launched, it had become apparent that existing rockets could only orbit fairly small payloads. Development was underway for the Atlas rockets, but von Braun foresaw a need for a launch vehicle designed to lift heavy payloads into space. This new rocket was to be a successor to the Jupiter rocket and was tentatively designated as the Jupiter V, though it was often referred to as the “super Jupiter.”

The Jupiter V project was approved in part because the Soviet Union had already developed very large rockets capable of lifting into orbit payloads far larger than those of any U.S. rocket at that time. Soon after ABMA began development of the Jupiter V at its site near Huntsville, Alabama, it became apparent that the new rocket would be of a totally new design and not merely an adaptation of the Jupiter rocket. Von Braun proposed that the name of the new rocket be “Saturn,” because that was the next planet from the Sun after Jupiter. The name was agreed to, and so from then on, the Jupiter V rocket under development was called the Saturn I rocket. The Saturn rocket would be able to lift into Earth orbit payloads far greater than those of any other U.S. rocket. Von Braun, however, was planning ahead. He proposed a new rocket, based on existing technology, that would be able to boost a payload to the Moon and back. The tentative name for this proposed new rocket was Nova. The Nova rocket, von Braun reasoned, would need nearly 12,000,000 pounds of thrust. This would require a first stage with more than fifty of the then-most powerful rocket engines.

The Advanced Research Projects Agency (ARPA), associated with ABMA, began test-firing of the engines for the first stage of the Saturn rocket in late 1958. The Saturn project was nearly canceled in June, 1959, when the U.S. Department of Defense decided that it did not really need a heavy-lift vehicle after all. ABMA was told to stop working on both Saturn and Nova. The initial proposed need for the development of the Saturn had been to launch orbiting communications satellites. It was found that such satellites would not be as heavy as had been thought. However, the National Aeronautics and Space Administration (NASA), the civilian space agency created in 1958, was very interested in both the Saturn and Nova rockets. Eventually, a deal was worked out to transfer von Braun, his rocket development team, and most of ABMA to the jurisdiction of NASA. The ABMA site in Huntsville became the Marshall Space Flight Center.

Work began immediately on the first of the Saturn rocket family, the Saturn I. During development of Saturn I, new engine technology was being developed that allowed modifications to the Saturn I. The improved rocket, designated the Saturn IB, was capable of lifting far heavier payloads. The Saturn I was never used except as a technological development stage toward later rockets.

The exact design of the Nova rocket would depend upon the mission characteristics and requirements of a crewed Moon program. In 1962, NASA’s Office of Manned Space Flight decided to use a lunar orbit rendezvous mission, in which a small lander, rather than the entire rocket, would descend to the lunar surface and then return to a mother ship orbiting the Moon. This method would require a rocket slightly smaller than von Braun’s proposed Nova rocket. It became apparent that the Saturn rocket program could be adapted and significantly enhanced to yield a rocket of specifications nearly like those of Nova. This new rocket, which was ultimately built, was designated the Saturn V rocket.

Saturn I

The Saturn I rocket was designed as a two-stage rocket. The upper stage would use liquid hydrogen as fuel and liquid oxygen as oxidizer. The first stage used kerosene (RP-1) and liquid oxygen. Liquid hydrogen is more energetic as fuel than kerosene but is harder to handle. Furthermore, hydrogen is lighter than kerosene, making it ideal for the upper-stage fuel. Kerosene, however, requires less storage space than does liquid hydrogen. Additionally, the rocket would be more stable with a heavier first stage, so kerosene was deemed the best fuel for first stage use.

The first stage of Saturn I, designated S-I, used eight H-1 engines, developed by the Rocketdyne Division of North American Aviation. Each engine provided 188,000 pounds of thrust. The four inboard engines were fixed in position, and the four outer engines were gimbaled, or suspended, to change direction slightly in order to steer the rocket. A decision was made to use existing Mercury and Jupiter propellant tanks to save development costs. The larger Jupiter tank was used for liquid oxygen. Clustered around it were four Redstone rocket oxygen tanks and four Redstone fuel tanks filled with kerosene. This clustering approach ensured that the fuel would not slosh around inside the large tank but made the plumbing of the system difficult. Although the first few S-I stages were constructed in-house by ARPA, the sheer magnitude of the project led to the selection of the Chrysler Corporation’s Space Division as a contractor to build the remaining S-I stages.

The Saturn I upper stage, designated S-IV, was constructed by Douglas Aircraft. Nearly two thirds of the S-IV was used by the liquid hydrogen tanks. Liquid hydrogen and liquid oxygen must be kept extremely cold, and so the propellant tanks were heavily insulated. This insulation, however, would be very heavy, and the lighter the stage, the higher the payload that could be delivered to orbit. North American Aviation devised a honeycomb aluminum insulation that was both very light and very strong. The honeycomb aluminum actually became stronger when cooled, so it was used to boost the strength of the propellant tanks, allowing the tank walls to be made thinner so that the tanks could be lighter. To power the S-IV stage, six Pratt & Whitney RL-10 engines were used, each providing 15,000 pounds of thrust.

Ten successful missions, beginning on October 27, 1961, were flown with Saturn I rockets. The first three involved the first stage only, with a dummy payload in place of the second stage. The last Saturn I rocket was launched July 30, 1965.

Saturn IB

The Saturn IB was essentially an upgrade of the Saturn I. Rocketdyne upgraded the H-1 engines to 200,000 pounds of thrust for the Saturn IB first stage, designated S-IB. Additionally, the dimensions of the first stage were slightly altered to couple with the redesigned upper stage. The S-IB had onboard computers and guidance systems intended to be used on the later Saturn V rockets. The rocket’s computers were constructed by International Business Machines (IBM). Although they were used for only a few minutes, they had to monitor a very large number of operations of the rocket.

The Saturn IB’s second stage, the S-IVB, was completely redesigned. The S-IVB used a liquid hydrogen and liquid oxygen propellant system and was powered by a single J-2 engine developed by Rocketdyne. The J-2 engine, with 200,000 pounds of thrust, provided the S-IVB with more than double the thrust of the S-IV used on Saturn I. The S-IVB was also configured to receive a collar on its top end to mate with payloads expected of the Apollo Program.

The first Saturn IB flew on February 26, 1966. Only four test flights were made with Saturn IB before the first crewed flight, Apollo 7, on October 11, 1968. Apollo 7 demonstrated the effectiveness of the Apollo spacecraft in an Earth-orbital mission. From this time until 1973, when the Apollo Program was canceled after the Apollo 17 mission, all remaining Apollo missions would use the Saturn V rocket. The Saturn IB, however, was used for three more missions in 1973 to launch Apollo capsules. The final launch of a Saturn IB was on July 15, 1975, when an Apollo capsule was launched to rendezvous with a Soyuz spacecraft launched by the Soviet Union.

Saturn V

In order to achieve the necessary thrust for a lunar mission, Rocketdyne developed the F-1 engines used in the Saturn V first stage. The F-1 engines burned 40,000 gallons of kerosene per second and provided a thrust of 1,600,000 pounds each. Each F-1 engine provided about the same thrust as the entire Saturn IB first stage. The Saturn V first stage was designated S-IC, and it was a complete redesign of the earlier first stages. Five F-1 engines were used. The center engine was fixed, and the outer four engines were gimbaled to steer the rocket. No other rocket had ever been constructed to match the 8,000,000-pound thrust of the S-IC. The S-IC, constructed by Boeing, was 33 feet in diameter and 138 feet in length. It contained enough kerosene and liquid oxygen in two giant tanks to fill more than fifty railroad tank cars.

The second stage of the Saturn V was a new design, designated the S-II. The S-II used five Rocketdyne J-2 engines. The S-II, constructed by North American Aviation, was also 33 feet in diameter and 81.5 feet in length. The S-II used liquid hydrogen and liquid oxygen as a propellant. The upper part of the S-II mated with a flared collar that fitted the more narrow third stage of the Saturn V.

The Saturn V’s third stage was the venerable S-IVB stage that had been used as the second stage to the Saturn IB. On top of the S-IVB was the payload for the Saturn V. For the Apollo missions, the payload had consisted of the Lunar Module, the Command Module, and the Service Module. The Service Module contained power systems for the Command Module and a rocket designed to return the Apollo spacecraft back to Earth from the Moon. On top of the Command Module was an escape tower that held rockets designed to lift the Command Module off of the Saturn V in the event of a catastrophic failure during launch. The total height of the rocket was 364 feet, and its total weight was more than 6,000,000 tons when fully fueled and ready for liftoff.

A total of fifteen Saturn V rockets were constructed. The first two launches on November 9, 1967, and April 4, 1968, were unmanned test missions. December 21, 1968, however, a Saturn V launched Apollo 8 on a trip around the Moon and back to Earth. On July 16, 1969, a Saturn V rocket, designated SA-506, launched Apollo 11, which was the first manned landing on the Moon. The last lunar mission was rocket SA-512, which launched Apollo 17. Only one other Saturn V rocket was launched. On May 14, 1973, SA-513 launched a modified S-IVB as Skylab, the first U.S. space station. The two remaining Saturn V rockets were never used, and became displays at the Kennedy Space Center and at the Johnson Space Center.

Bibliography
  • Bilstein, Roger E. Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles. Washington, D.C.: Government Printing Office, 1996. An authoritative and thorough, though readable, description of the entire Saturn project from first conceptions to the program’s spinoffs.
  • Braun, Wernher von. “Saturn the Giant.” In Apollo Expeditions to the Moon, edited by Edgar M. Cartright. Washington, D.C.: Government Printing Office, 1975. An excellent description of the Saturn rockets for the layperson, written by the lead designer himself.
  • Heppenheimer, T. A. Countdown: A History of Space Flight. New York: John Wiley & Sons, 1997. A very readable history of space exploration, with a section on the Apollo lunar exploration.
  • Kennedy, Gregory P. Rockets, Missiles, and Spacecraft of the National Air and Space Museum. Washington, D.C.: Smithsonian Institution Press, 1983. A very good, though brief, description of the H-1 and F-1 rocket engines.

Apollo Program

Wernher von Braun

Crewed spaceflight

Robert H. Goddard

Johnson Space Center

Missiles

National Aeronautics and Space Administration

Orbiting

Rocket propulsion

Rockets

Spaceflight

Uncrewed spaceflight

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