The S-IVB (pronounced "S-four-B") was the third stage on the

Saturn V Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, with multistage rocket, three stages, and powered with liquid-propellant r ...

and second stage on the

Saturn IB The Saturn IB (also known as the uprated Saturn I) was an American launch vehicle commissioned by the National Aeronautics and Space Administration (NASA) for the Apollo program. It uprated the Saturn I by replacing the S-IV second stage (, 43 ...

launch vehicles. Built by the

Douglas Aircraft Company The Douglas Aircraft Company was an American aerospace manufacturer based in Southern California. It was founded in 1921 by Donald Wills Douglas Sr. and later merged with McDonnell Aircraft in 1967 to form McDonnell Douglas; it then operated a ...

, it had one J-2 rocket engine. For lunar missions it was fired twice: first for Earth orbit insertion after second stage cutoff, and then for

translunar injection A trans-lunar injection (TLI) is a propulsive maneuver used to set a spacecraft on a trajectory that will cause it to arrive at the Moon. History The first space probe to attempt TLI was the Soviet Union's Luna 1 on January 2, 1959 which wa ...

(TLI).

History

The S-IVB evolved from the upper stage of the

Saturn I The Saturn I was a rocket designed as the United States' first medium lift launch vehicle for up to low Earth orbit payloads.Terminology has changed since the 1960s; back then, 20,000 pounds was considered "heavy lift". The rocket's first st ...

rocket, the S-IV, and was the first stage of the

to be designed. The S-IV used a cluster of six engines but used the same fuels as the S-IVB – liquid

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...

and liquid

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

. It was also originally meant to be the fourth stage of a planned rocket called the C-4, hence the name S-IV. Eleven companies submitted proposals for being the lead contractor on the stage by the deadline of 29 February 1960. NASA administrator

T. Keith Glennan Thomas Keith Glennan (September 8, 1905 – April 11, 1995) was the first Administrator of the National Aeronautics and Space Administration, serving from August 19, 1958 to January 20, 1961. Early career Born in Enderlin, North Dakota, the son ...

decided on 19 April that Douglas Aircraft Company would be awarded the contract.

Convair Convair, previously Consolidated Vultee, was an American aircraft manufacturing company that later expanded into rockets and spacecraft. The company was formed in 1943 by the merger of Consolidated Aircraft and Vultee Aircraft. In 1953, i ...

had come a close second but Glennan did not want to monopolize the liquid hydrogen-fueled rocket market as Convair was already building the Centaur rocket stage. In the end the

Marshall Space Flight Center The George C. Marshall Space Flight Center (MSFC), located in Redstone Arsenal, Alabama (Huntsville postal address), is the U.S. government's civilian rocketry and spacecraft propulsion research center. As the largest NASA center, MSFC's firs ...

decided to use the C-5 rocket (later called the Saturn V), which had three stages and would be topped with an uprated S-IV called the S-IVB which instead of using a cluster of engines would have a single J-2 engine. Douglas was awarded the contract for the S-IVB because of the similarities between it and the S-IV. At the same time it was decided to create the C-IB rocket (Saturn IB) that would also use the S-IVB as its second stage and could be used for testing the Apollo spacecraft in Earth orbit.

Configuration

Douglas built two distinct versions of the S-IVB, the 200 series and the 500 series. The 200 series was used by the Saturn IB and differed from the 500 in that it did not have a flared interstage and it had less helium pressurization on board since it did not have to be restarted. In the 500 series, the interstage needed to flare out to match the larger diameter of the

S-IC The S-IC (pronounced S-one-C) was the first stage of the American Saturn V rocket. The S-IC stage was manufactured by the Boeing Company. Like the first stages of most rockets, most of its mass of more than at launch was propellant, in this cas ...

and

S-II The S-II (pronounced "S-two") was the second stage of the Saturn V rocket. It was built by North American Aviation. Using LH2, liquid hydrogen (LH2) and liquid oxygen (LOX) it had five J-2 (rocket engine), J-2 engines in a quincunx pattern. The ...

stages of the Saturn V. The 200 series also had three solid rockets for separating the S-IVB stage from the S-IB stage during launch. On the 500 series this was reduced to two, and two small Auxiliary Propulsion System (APS) thruster modules were added as

ullage motor Ullage motors (also known as ullage engines or ullage rockets) are relatively small, independently fueled rocket engines that may be fired prior to main engine ignition, when the vehicle is in a zero-g situation. The resulting acceleration cause ...

s for restarting the J-2 engine and to provide attitude control during coast phases of flight. The S-IVB carried of

liquid oxygen Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an app ...

(LOX), massing . It carried of

liquid hydrogen Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point of 33 K. However, for it to be in a fully l ...

(LH2), massing . Empty mass was

Auxiliary Propulsion System

Attitude control was provided by J-2 engine gimbaling during powered flight and by the two APS modules during coast. APS modules were used for three-axis control during coast phases, roll control during J-2 firings, and ullage for the second ignition of the J-2 engine. Each APS module contained two thrusters providing thrust for roll and pitch, another thruster for yaw, and one thruster for ullage. Each module contained its own propellant tanks of

dinitrogen tetroxide Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...

and monomethyl hydrazine as well as compressed helium to pressurize its propellants.

Uses

A surplus S-IVB tank, serial number 212, was converted into the hull for the

Skylab Skylab was the first United States space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three separate three-astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Major operations ...

, the first American

space station A space station is a spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station ...

. Skylab was launched on a Saturn V on May 14, 1973, and it eventually reentered the atmosphere on July 11, 1979. A second S-IVB, serial number 515, was also converted into a backup Skylab, but this one never flew. During the missions of

Apollo 13 Apollo 13 (April 1117, 1970) was the seventh crewed mission in the Apollo space program and the third meant to land on the Moon. The craft was launched from Kennedy Space Center on April 11, 1970, but the lunar landing was aborted aft ...

Apollo 14 Apollo 14 (January 31, 1971February 9, 1971) was the eighth crewed mission in the United States Apollo program, the third to land on the Moon, and the first to land in the lunar highlands. It was the last of the " H missions", landings at ...

Apollo 15 Apollo 15 (July 26August 7, 1971) was the ninth crewed mission in the United States' Apollo program and the fourth to land on the Moon. It was the first J mission, with a longer stay on the Moon and a greater focus on science than ear ...

Apollo 16 Apollo 16 (April 1627, 1972) was the tenth human spaceflight, crewed mission in the United States Apollo program, Apollo space program, administered by NASA, and the fifth and penultimate to Moon landing, land on the Moon. It was the second o ...

, and

Apollo 17 Apollo 17 (December 7–19, 1972) was the final mission of NASA's Apollo program, the most recent time humans have set foot on the Moon or traveled beyond low Earth orbit. Commander Gene Cernan and Lunar Module Pilot Harrison Schmitt walke ...

, the S-IVB stages were crashed into the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

to perform seismic measurements used for characterizing the lunar interior. File:As7-3-1545.jpg,

Apollo 7 Apollo 7 (October 1122, 1968) was the first crewed flight in NASA's Apollo program, and saw the resumption of human spaceflight by the agency after the fire that killed the three Apollo 1 astronauts during a launch rehearsal test on Ja ...

S-IVB in orbit over

Cape Canaveral , image = cape canaveral.jpg , image_size = 300 , caption = View of Cape Canaveral from space in 1991 , map = Florida#USA , map_width = 300 , type = Cape , map_caption = Location in Florida , location ...

. File:Saturn IB Second Stage with open LM adapter.jpg, Distant view of Apollo 7 S-IVB stage File:As08-16-2584.jpg,

Apollo 8 Apollo 8 (December 21–27, 1968) was the first crewed spacecraft to leave low Earth orbit and the first human spaceflight to reach the Moon. The crew orbited the Moon ten times without landing, and then departed safely back to Earth. The ...

S-IVB, shortly after separation

Stages built

(* See

List of artificial objects on the Moon This is a partial list of artificial materials left on the Moon, many during the missions of the Apollo program. The table below does not include lesser Apollo mission artificial objects, such as a hammer and other tools, List of retroreflectors o ...

for location.)

Derivatives

The second stage of the

Ares I Ares I was the crew launch vehicle that was being developed by NASA as part of the Constellation program. The name "Ares" refers to the Greek deity Ares, who is identified with the Roman god Mars. Ares I was originally known as the "Crew Launc ...

rocket and the proposed Earth Departure Stage (EDS) would have had some of the characteristics of the S-IVB stage, as both would have had an uprated J-2 engine, called the J-2X, with the latter performing the same functions as that of the Series 500 version of the stage (placing the payload into orbit, and later firing the spacecraft into trans-lunar space). The MS-IVB was a proposed modification of the S-IVB that would have been used on a Mars flyby, but it was never produced.

References

* Marshall Space Flight Center,
Apollo Systems Description Volume II - Saturn Launch Vehicles
', 1 February 1964.
Archived copy, pdf

External links

NASA New Reference: Saturn third stage
{{DEFAULTSORT:S-Ivb Apollo program Rocket stages Impactor spacecraft