Short answers, pulled from the story.
Konstantin Tsiolkovsky was a Russian rocket scientist born in the 19th century who pioneered astronautics and is recognized as one of the founding fathers of modern rocketry. Along with Hermann Oberth and Robert H. Goddard, he is counted among the pioneers of spaceflight. His mathematical work, particularly the Tsiolkovsky rocket equation, laid the theoretical foundation for all subsequent rocket engineering.
The Tsiolkovsky rocket equation establishes the relationship between a rocket's change in speed, the exhaust velocity of its engine, and the ratio of the rocket's initial mass (including fuel) to its final mass. Tsiolkovsky recorded the date he completed it as the 10th of May 1897. He called it the "formula of aviation," and it remains fundamental to spacecraft propulsion design.
In May 1903, Tsiolkovsky published "Exploration of Outer Space by Means of Rocket Devices." In it he calculated that the horizontal speed required for a minimal Earth orbit is 8,000 meters per second and proposed that a multistage rocket fueled by liquid oxygen and liquid hydrogen could reach that speed. It was the first publication to suggest that a rocket could perform actual spaceflight.
Tsiolkovsky lost his hearing at the age of 9 after catching scarlet fever. Because of his hearing problem, he was not admitted to elementary schools and was self-taught. He educated himself primarily through books, developing strong interests in mathematics and physics.
Soviet search teams at Peenemünde found a German translation of a book by Tsiolkovsky with almost every page marked by Wernher von Braun's handwritten comments and notes. Leading Soviet rocket engineers Valentin Glushko and Sergei Korolev studied Tsiolkovsky's works as youths and both sought to turn his theories into reality, contributing directly to the achievements of the Soviet space program.
In his 1928 book "The Will of the Universe: The Unknown Intelligence," Tsiolkovsky presented a philosophy of panpsychism and believed humans would eventually colonize the Milky Way galaxy. He rejected traditional religious cosmology in favor of a mechanical view of the universe governed by a cosmic intelligence. In a 1933 article, he explicitly described what would later be called the Fermi paradox.