Konstantin Tsiolkovsky was born in 1857 in the Siberia area of Russia. His father was Polish and had been deported there. When he was ten years old, he sickened with Scarlet Fever which caused him to lose most of his hearing. He chose not to let it slow him down.
Due to the hearing loss, he was educated at home and when he was old enough, his family sent him to attend college in Moscow. While there, he obtained an solid education in science and mathematics but when his father discovered he was overworking himself, he was called home where he took exams to become a teacher and passed. At the same time as working as a teacher, he read Jules Verne stories of space travel and he even began to write science fiction.
From here, he transitioned to writing scientific papers on gyroscopes, rocket control, rocket fuel, escape velocities and how action and reaction works in space travel. In addition, he studied the Chinese rockets and used math and science to create rocket dynamics. This lead to him to publish the equations in a Russian aviation magazine and was called the Tsiolkovsky Formula. This formula laid out the relationships between rocket speed, the speed of gas at its exit, the mass of the rocket and it's propellants. It is the Tsiolkovsky Formula which formed the basis of much of the modern space craft engineering.
Furthermore, he is responsible for building Russia's first wind tunnel so various aircraft designs could be tested to determine their aeronautical abilities. Since no one was willing to help finance the wind tunnel, he dipped into his family's monies to pay for it. He spent so much of his adult life exploring topics associated with aerodynamics, rockets, heat transfer, friction, and other such topics but the Aeronautics congress helped in St. Petersburg didn't think much of his research.
In addition, he published the Investigations of Outer Space By Rocket Devices in 1911 and the Aims of Astronauts in 1914. Furthermore, he published information about his theory of multistage rockets based on his knowledge of propellants dynamics in 1929. By 1921, the predecessor of the Academy of Science chose to elect him as a member and granted him a pension for all the contributions he made. He died in 1935 but his knowledge was used in creating both the Russian and American Space problems. He shares the honor of being the Father Of Modern Rocketry with Goddard and Oberth since all three of these people came up with much of the same information independently.
I chose Tsiolkovsky since he majored in Math in college, taught school, and managed to develop foundational concepts that contributed to the development of the space program. Let me know what you think, I'd love to hear. Have a great day.