The manned test and lunar landing missions of the Apollo program used the majestic Saturn V lunar launch vehicle for all but one flight.

Yet millions of dollars were spent on building, perfecting and launching two central elements of the earliest Apollo designs. Despite NASA’s intention to use these elements for early earth-orbital tests of Apollo, they never flew with a crew.

The “Super-Jupiter”: Or, No Plan Survives First Contact with Reality

It might not surprise some of you that the massive rocket family that would eventually send men to the moon began as a project in 1957 for the U.S. Army, specifically, the Army Ballistic Missile Agency (ABMA). The Army, by request of the Department of Defense, wanted to lift large satellites into space (read: “We like the idea of spy and weapon platforms orbiting the Earth).

ABMA had several advantages on their side to make this new rocket. For one, the Army’s central brain trusts in missile development included Wernher von Braun. At Redstone Arsenal, von Braun and his team developed (among others) the Redstone and Jupiter missiles.

Von Braun and his team calculated that a rocket that could lift heavy payloads would need a much higher thrust than anything they’ve made. The Jupiter and Redstone missiles, respectively, had around 150,ooo pounds (620,000 Newtons) and 78,000 pounds (350,000 Newtons) of thrust. The new vehicle would need (at least) ten times more than the Jupiter: Ar least 1.5 million pounds (6.7 million Newtons) to accomplish the goal.

So the German team’s solution was novel: Take a Jupiter tank and surround it with eight Redstones. As neither the engines of these two vehicles would cut the mustard, a new engine would be used, forming what was then a dangerous cluster of four engines that would produce the needed thrust. The team also heard of a new engine being worked on by the Air Force that, from one engine alone could produce the needed 1.5 million pounds of thrust, but it wouldn’t be available by the time that the DoD would want to see a result.

A new government agency was created to fine-tune the requirements of the new rocket: ARPA, or the Advanced Research Projects Agency. If that acronym seems familiar, you might know it today as DARPA, the same agency with a “D” that also funds and support non-military technology developments, such as self-driving vehicles. They also, in the course of time, were responsible for a little computer network project that become the internet.

ARPA modified the four-cluster Super-Jupiter concept to an extraordinary eight-engine design based on upgraded engines used on other missiles, rather than engines that were still under development. By 1958, the project, called “Juno V” by von Braun, was official and in development.

The Dream Grows Up

As 1959 approached, the Juno V’s specifications grew. Additional rocket stages would be needed to push the heavier payloads. By 1958, in the wake of the Soviet’s launch of Sputnik, a smaller government agency got a new name and a new involvement with ARPA and ABMA’s work: the National Aeronautics and Space Administration.

Among other objective, the young NASA was tasked to look at all the various Army and Air Force and DoD space projects and consolidate, adopt or adapt such projects to show a public challenge to the Soviets of space dominance. Von Braun was later brought in assist in supporting or recommending consolidation or cancellation of the many projects, often redundant to each other, found in the various agencies

All that time, a new nickname circulated for the new vehicle. “Super-Jupiter” never rolled off the tongue. But “Saturn” did. It was catchy because Saturn was “the one after Jupiter” in both astronomical and missile development terminology. By 1958 that name become official.

Saturn was almost cancelled by a DoD official, concerned that the project was sapping resources from ARPA. Supporters in both DoD, NASA and ARPA made their case against the cancellation. NASA was particularly worried because the military and DoD, a third-party supplier to them of any rockets, were becoming fickle, threatening their central objectives of sending a man in space.

In the end, the DoD relented and Saturn would survive–on the condition that the project would be entirely transferred to NASA–and von Braun’s ABMA team with it.

More Plans Get Crushed by New Developments

Between 1958 to 1960, various groups debated on the second stage’s design. Some wanted to use a Centaur or Titan derived stage. Then size changes, specifically the stage’s diameter, nixed that plan. The Air Force hoped that a Saturn vehicle would be a better fit for their new spaceplane concept, the Dyna-Soar. Another advisory committee was formed and planned out some ideas.

In the end, rather than rocket stages with a mix of hypergolic fuels like Titan, the recommended designed formed up into three rockets: A two-stage rocket, a four-stage intermediate rocket and a very large three-stage high performance rocket. The first stages would use RP-1 (a type of kerosene) and oxygen, but the upper stages would use hydrogen and oxygen.

The stage names reflected their order, at first. There were the S-I, S-II, S-III, and S-IV stages, and even an S-V stage, built on Centaur technology.

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SA-1, the first of many in the Saturn family. (NASA)

Over time, the S-IV stage, originally meant to use four engines, was redesigned with six RL-10 engines. The new rocket, the Saturn I, the S-I Jupiter-wrapped-in-Redstones derived stage, flew first, with a dummy upper stage, on the SA-1 test on October 27, 1961, to great fanfare by its creators. No new rocket, much less one of that immense size, had ever launched without significant failure.

But the Saturn I flew, and flew again four additional times before an S-IV stage was added and also launched successfully.

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The stark beauty of Saturn I SA-5. (NASA)

This sixth Saturn I variant now had larger first stage fuel tanks, large fins for added flight stability and a dummy payload painted black. The contrast made the SA-5 rocket one of the most gorgeous things that NASA ever flew.

Other groups who considered Saturn for their uses wondered off. The Army’s attention returned to ground-pounding, especially concerned with events in south Asia. The Air Force got their Titan rockets in several variations that satisfied their needs (although none would fully launch their early man-in-space dream projects: Dyna-Soar and the Manned Orbiting Laboratory).

By 1961, the Soviets won the second goal of the Space Race, sending a man into earth orbit. President Kennedy asked various aides what the U.S. could do to show a clear win against the Russians. They told him. Kennedy liked this ambitious idea of sending a man to the moon, but waited for NASA to give him a trump card that showed America (and those in Congress) that NASA could put an American in space, albeit briefly, thus having the capacity to achieve Kennedy’s goal (and get funding to do it).

The First Command Module

The Apollo program, a multi-use spacecraft for orbital and lunar missions, was actually in the table over a year before President Kennedy’s commitment to a lunar landing mission.The central manned part of Apollo, the Command Module, was actually four separate ideas from different contractors. Eventually, the design of NASA’s Max Faget, central designer of the Mercury and Gemini spacecraft, won out.

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Various ideas of a direct-ascent Apollo monolithic spacecraft. (NASA)

Faget’s conical Command Module was originally designed as part of a much larger spacecraft that would land on the moon. That’s why the first Command Module design had a solid nose; as there were no ideas for it to connect, or dock, with anything.

This Command Module would could fly in a direct-ascent liftoff, requiring a MUCH larger rocket than even the largest Saturn design, the “C-5”. To avoid building the terrible rocket beast that would dwarf Saturn, the Nova, the earth-orbit rendezvous trajectory became popular. Using two heavy-lift Saturns, one for the spacecraft and another with the fuel and propulsion modules, the two separately launched elements would mate up in earth orbit and head to the moon.

What became clearer (especially thanks to the persistence of dissenters, particularly John Houbolt), even earth-orbit rendezvous would be extremely impractical. Each Saturn would need to lift an enormous amount of fuel and vehicle into orbit.

Further, the monolithic Apollo spacecraft, Command Module atop it, was to land directly on the moon, not only carrying the fuel and equipment needed to land, but all the engines and fuel needed for lunar liftoff and to return to earth. It was too much weight. No one even knew if the moon could hold that much mass on its surface without collapsing.

Houbolt and others convinced NASA that a third option, a smaller, much lighter separate spacecraft, designed only to land and return from the lunar surface, could be launched with the non-landing Command Module, which would become a mothership, mated and separating in lunar orbit. By 1962, the idea took hold and Grumman was soon chosen to build a lander.

But by 1963, the Apollo Command Module design as a direct ascent, earth orbit rendezvous vehicle was already in the construction stage. Rather than wasting what was already made now that lunar-orbit rendezvous was the method to the moon, NASA decided to form two design tracks for the Command Module. The original design became the “Block I” and be used for earth-orbit tests. With lunar-orbit rendezvous, additional design changes added a docking tunnel and other elements to form the “Block II,” for the lunar landing missions.

The early project Apollo development planned to use the Saturn I for CM-only tests. An uprated version of the Saturn I, called the Saturn I-B (or “IB”), would fly the CM and new Lunar Module for earth orbit testing as a pair. The heavy-lifting Saturn V, using the F-1 engines that started development long ago under the Air Force, would send that all to the moon.

Fire Consumes But Purifies

The Command Module’s needs evolved. More equipment was needed. The idea of returning to earth and landing on land gave way to splashdowns, else, the spacecraft would become heavier to fortify it. Early splashdown tests revealed that the heat shield bulkhead would break and sink the Command Module, so additional reinforcements added more weight.

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Saturn I launch test, appearing as an earth-orbital Apollo configuration (but with a boilerplate), on SA-7, AS-102, September 1964. (NASA)

By 1964, the Saturn I’s final design was enough to launch a few boilerplates of the Block I Command Module, as well as tests to see how water or fuel would behave in a high-altitude explosion (Project Highwater) as well as an orbital micrometeoroid analyst project (Pegasus).

But the introduction of the far more powerful J-2 engine on the augmented S-IV stage it used, the S-IVB, meant that the uprated Saturn, the I-B rocket, would be a better fit to launch the final Command Modules and the upcoming Lunar Modules for earth-orbit tests. Made obsolete by its own improvements incorporated into the uprated brother and by spacecraft that grew too fat, the Saturn I was discontinued, never to fly a crew.

Eventually, even the versatile Saturn I-B couldn’t lift a Lunar Module and Command/Service Module into earth orbit together as the near-completed LM and CSM turned out heavier than expected. Only the rocket designed to send them to the moon, the Saturn V, would ever fly the two spacecraft together.

The Saturn I-B would fly a few unmanned tests of boilerplate and Block I Command Modules before it was tasked to launch the first manned Apollo flight in February 1967.

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Spacecraft 012. (NASA)

But this was not to be. The Block I Command Module itself had significant design flaws and poor construction procedures and quality control, which appeared in a terrifying and tragic way with a fire in Spacecraft 012, killing the first Apollo crew during a pad test on January 27, 1967.

Apollo was setback for 18 months. Block I development and construction was completely stopped and improvements in safety and quality for the Command Module were incorporated into the lunar Block II spacecraft. Two Block Is were launched (often with Block II elements for testing) on the first Saturn V test flights, Apollo 4 and 6, and that was it. The Block I CM joined the Saturn I on the scrapheap.

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The Saturn I-B variations. Because of weight, the Saturn I-Bs could never lift both LM and CSM at once, despite the expectations. (NASA)

The Saturn I’s improved twin flew Apollo 7, the first manned mission, in October 1967. To get ahead in the race to the moon in light of U.S. intelligence reports on the Soviet moon rocket, the N-1, further use of the I-B was suspended and all other Apollo flights used Saturn Vs.

The remaining I-B rockets would be dusted off to fly four more times after the last lunar landing, three for shuttling the Skylab crews to their space station, and a final mission to put a close to the Space Race, which sparked the development of the Saturn to begin with, docking with a Russian Soyuz spacecraft in July 1975. The remaining I-Bs now rest in various museums and even a road-side rest stop at the northern edge of Alabama.

Despite a few close calls, the Saturn rocket remains one of the most reliable rockets in history. None were ever lost, and all crews that flew on them accomplished their missions and returned home. One of the spare S-IVBs of a Saturn I-B gained special honors by being converted into Skylab–which was lifted atop the last Saturn V to fly.

So, while the Saturn V rockets gained the limelight, the smaller Saturns (which shared the central guidance and navigation elements with their lunar brother) contributed much to the development of the rocket family. The long development history of the Command Module and the flawed construction that killed one crew would redeem the makers of not only one but two spacecraft. The Lunar Module’s electrical and safety features were also modified with the Fire. LM-7 saved a Command Module that lost power, through no fault in itself, during Apollo 13. Nearing re-entry, the revived Command Module, soaked in condensation and cold, did not fail to return its crew home.