Hermann Koelle, the Most Important German Rocket Scientist You’ve Probably Never Heard Of

A key advisor to Wernher von Braun, he helped shape NASA’s space strategy during the agency’s golden age.

Heinz-Hermann Koelle, holding a copy of Wernher von Braun's book The Mars Project, which Koelle helped to get published in Germany. (Courtesy Karin Koelle)
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By any measure, Wernher von Braun was the leading figure in the history of rocket development in pre-World War II and wartime Germany. And at the war’s end, von Braun and his talented team of engineers and scientists were transplanted as a group to the United States. In fact, it was that cadre of German rocketeers who deserve the most credit for conceiving and building the mighty Saturn V that carried the first people to the Moon.

Yet one of the most essential German members of the Saturn team—Heinz-Hermann Koelle—didn’t arrive with the original group captured by U.S. agents in 1945. He joined them in Huntsville, Alabama, almost a decade later, when work on the first American rockets was already well under way. That may account for the fact that very few people remember his name today.

Although Koelle was 13 years younger than von Braun, they had much in common. Both were intense dreamers in their youth, captivated by the promise of spaceflight. Their personalities were different, however, and their careers took quite different paths. Von Braun was gregarious, and did not mind the limelight. Koelle, even well into his NASA career, granted very few interviews to the press.

As a teenager in the late 1920s, von Braun had joined an amateur rocket group called the Verien für Raumschiffahrt (the Society for Spacefight) that conducted crude experiments with liquid-fuel rockets. He was secretly hired by the German Army in 1932 to develop the technology further, and eventually became Technical Director at the sprawling, top secret Peenemünde research center opened in 1936, which ultimately produced the V-2, the worlds first large-scale liquid-propellant rocket.

Koelle had no connection to the pioneering work at Peenemünde. Born in 1925 in the Free State of Danzig, Germany (now, Gdańsk, Poland) he became fascinated with aviation as a 10-year-old when, during a family vacation, he took a 20-minute hop in a Junkers F13, the worlds first all-metal transport aircraft. He resolved to become a pilot, although the nearest he came was to take up gliding as a teenager. Then, in 1941, as a 16th birthday gift, Hermann received the book Wege zur Raumschiffahrt (Ways to Spaceflight) written in 1929 by Herman Oberth. That motivated him to learn more about spaceflight, just as Oberths first book, Die Rakete zu den Planetenräumen (The Rocket into Interplanetary Space, published in 1923) had influenced von Braun. It would be years, though, before Koelle got into rocketry himself.

In January 1942, he volunteered to join the Luftwaffe, thereby avoiding the possibility of being drafted into another branch of the military. It also gave him the chance to become a pilot; he trained to fly the Ju 52, the He 111, and other aircraft. Late in the war, after a few night combat missions, his Focke-Wulf FW-190 single-seat fighter was shot down by American anti-aircraft fire near Erklenz in western Germany, during his first daylight mission. Koelle was forced to make a belly landing in his burning aircraft, and was captured by American forces and kept as a POW through the end of the war.

From 1946 to 1949, while studying at the Stuttgart Institute of Technology (now the University of Stuttgart) to become an engineer, Koelle resumed his reading about spaceflight. In 1948 he helped re-establish the Gesellschaft für Weltraumforschung e.V. (the GfW, or Society for Space Research), the first major postwar spaceflight advocacy group in Germany. Enthusiasm for spaceflight continued to flourish in the country, even though at the time, Germans were prohibited from building rockets.

Koelle was the driving force of the new group, which had to confine its activities to lectures, publishing technical papers, and producing a monthly journal called Weltraumfahrt (Spaceflight), of which young Koelle was the editor. He set about offering honorary GfW memberships to leading lights in the astronautical world, and in early February 1949 the society made Professor Oberth its honorary president. Shortly thereafter, Koelle made his first contact with von Braun, who had moved along with core members of his original V-2 team to the U.S. Armys Redstone Arsenal in Huntsville, Alabama, and was now granted honorary membership in Koelle’s Society.

By this time, Koelle had become something of an authority on the possibilities of space stations. Logically, he began to branch out to design the heavy-lift launch vehicles that could be used to build these massive structures. Meanwhile, he continued to network. In 1949, in collaboration with Heinz Gartmann, another GfW member, he recommended “an international meeting of all societies for rocket development...and space exploration...with the aim of founding an international consortium for astronautics.” This resolution was circulated to all known rocket and spaceflight groups and led to the founding of the International Astronautical Federation (IAF) in 1952. Koelle and Gartmann get credit for establishing the annual IAF congresses and the International Astronautical Congress (IAC), as it is called today—still the largest yearly event held by the global spaceflight community.

While von Braun worked on the complex engineering challenges of building liquid-propellant rockets in Huntsville, he drew up his own futuristic space plans, which included a space station. Von Braun called his plan The Mars Project, but had difficulty getting the manuscript published—until Koelle came to the rescue. According to Rob Godwin, co-author of Outpost in Orbit, a definitive history of space stations, when von Braun sent Koelle his manuscript, the younger man sent back a critique with his own his calculations “for what he called the ‘optimum rocket’ that could accomplish many of von Braun's goals.” Von Braun was highly impressed with Koelles engineering abilities and far-sightedness, and went on to incorporate his methods into the book. It was through Koelle that it was first published in Germany as Das Mars Projekt (The Mars Project).

Koelle continued his formal studies, and for his diploma thesis for the German equivalent of a Masters of Science degree in Engineering, he designed an advanced, 100-tons-of-thrust rocket engine using liquid oxygen and hydrazine propellants. That led, following his graduation in 1954, to von Braun inviting him to join his team at the U.S. Armys Redstone Arsenal in Huntsville. Why? Even though von Braun was already surrounded by experienced V-2 rocket engineers, he recognized that young Koelle possessed the rare talent of being able to envision and design—in exacting engineering detail—huge space structures that might be constructed in the future.

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Koelle (center) at the Redstone Arsenal in Alabama in 1957. (Courtesy Karin Koelle)

Koelle was assigned initially as a research scientist, but he rapidly rose to become a leading scientific advisor to von Braun, and played a role in designing an extended re-entry version of the Redstone ballistic missile. With upper stages added, that became the Jupiter-C, which, on January 31, 1958, lifted America's first successful satellite, Explorer 1, into space. Koelle was on the launch crew for that historic flight.

During these first years of the U.S. space program, Koelle helped lay the foundations for what became the Saturn family of heavy-lift launch vehicles. He was one of the select team of 11 designers of the Saturn I, and worked on the preliminary design of the Saturn V. In those heady pioneering days of spaceflight, he even came up with detailed plans to reach the moon.

Early in July 1960, Koelle was transferred with other von Braun team members to the recently formed National Aeronautics and Space Administration (NASA) and its new Marshall Spaceflight Center in Huntsville. At the civilian space agency, he advanced to become head of the Future Projects Office. In that position, Koelle was what we would today call a strategist. At a time when NASA was perhaps at its most ambitious, that made him one of the agency’s most influential people. In December 1958, before he even officially came on board, he and von Braun made a presentation to the heads of NASA with his idea for a “National Integrated Launch Vehicle” strategy. This called for building a limited number of launch vehicles that together could handle all the countrys needs—rather than building custom rockets for each payload. The strategy evolved into the “building block approach,” in which interchangeable stages could be added or subtracted as required.

Ultimately, this highly practical approach led to the Apollo spacecraft and Saturn IVB third stage being compatible with both the Saturn IB and Saturn V vehicles. NASAs first space station plans also came out of his office. Koelle was the first to suggest, in a proposal submitted to von Braun in 1963, that a station could be built using one Saturn V and one Saturn IB. This idea evolved into Skylab, which reached orbit in 1973.

Over the course of his NASA career, Koelle issued some of the first contracts to aerospace companies for studying such topics as rendezvous techniques, guidance systems, and reusable orbital vehicles that would later serve as the basis for the Space Shuttle. In essence, he oversaw all aspects of future spaceflight planning for NASA, and managed along the way to earn his Ph.D in Aeronautical Engineering.

He ended up leaving America, however. Koelle remained with the von Braun team until late 1965, when he accepted a position as Professor of Air and Spaceflight at the Technical University of Berlin. Since the title had been previously held by Austrian astronautics pioneer Eugen Sänger (who died in February 1964), Koelle has been called the “second Professor of Spaceflight” in Europe. He remained in that post for 30 years, retiring in 1991. He continued to be remarkably prolific in his writings on futuristic space topics, especially space stations and scientific lunar bases. Over the course of his career he was accorded several honors, including the Hermann Oberth Medal from the German Society for Rocket Technology and Spaceflight. Koelle died in 2011 at 85.

Recently, his family graciously donated a collection of Koelle's papers, along with his impressive book and manuscript collection, to the Archives of the Deutsches Technikmuseum (The German Technical Museum in Berlin). The new Koelle Collection, covering the gamut of topics in astronautics from 1948 to 2010, will now be open to all researchers interested in the development of spaceflight.

As Koelle himself observed: “Over the past 60 years, a lot of valuable material has accumulated in my library, especially since I was an avid collector of relevant historical resources.” It would be fitting if this important figure becomes better known as a result of his family’s gift.

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