Eugen Sänger: Eminent space pioneer

In international literature on astronautics, three main space pioneers are mentioned: Konstantin E. Tsiolkovsky, Robert H. Goddard and Hermann Oberth. There are other two space pioneers that are very rarely mentioned: Robert Esnault-Pelterie and Eugen Sänger. Pelterie is known particularly in Europe, and Sänger is mentioned in the second half of the 20th century normally only in connection with space shuttle flights.Taking a look at Sänger's work and heritage, it is obvious that he greatly influenced the development of astronautics in terms of purely theoretical dissertations on achievable limits of space research as well as in terms of technical approaches to achieving the short- and long-term goals of astronautics, and in terms of setting tasks for organizing mankind to achieve these goals. Sänger's book “The Technology of Rocket Flight” was the first study based not only on basic research, but also on the applied research that he conducted and the findings of which he published in various papers. Sänger was clearly connected with and influenced the development of two experimental research groups in the US in the 1930s, which resulted in two of the most significant companies in the US in the 1950s that manufactured liquid propellant rocket engines. Basic and applied research in the field of space planes resulted in construction of rocket planes such as the US space shuttle and Soviet Buran shuttle.Sänger's research on subsonic and supersonic ramjets in combination with a turbojet engine provided a basis for developing this promising propulsion for use in subsequent space planes designed for flights into low Earth orbits. His pioneering work on the photon rocket represents human achievements in reaching almost unimaginable limits of space research.By striving for a peaceful international approach to space research, Sänger participated in establishing the non-governmental organization IAF (International Astronautical Federation) and realized his idea that space research is a concern for all mankind. He was therefore appointed the first president of the IAF.The paper presents how Sänger influenced the development of rocket technology and astronautics, which definitely ranks him with the first three space pioneers.