Russian physicist and theoretical father of rocketry. Tsiolkovsky was the son of a Polish deportee to Siberia. Tsiolkovsky was an inventor and aviation engineer who was also an insightful visionary. As early as 1894, he designed a monoplane which subsequently flew in 1915. He also built the first Russian wind tunnel in 1897. In 1903, as part of a series of articles in a Russian aviation magazine, Tsiolkovsky published the rocket equation, and in 1929, a theory of multistage rockets. Tsiolkovsky was also the author of Investigations of Outer Space by Rocket Devices (1911) and Aims of Astronauts (1914).

One of Tsiolkovsky's many memorable and inspiring quotes is "Mankind will not forever remain on Earth, but in the pursuit of light and space will first timidly emerge from the bounds of the atmosphere, and then advance until he has conquered the whole of circumsolar space" (1911). Tsiolkovsky's most famous quote is, "Earth is the cradle of humanity, but one cannot remain in the cradle forever."

Goddard, Oberth