Konstantin Tsiolkovsky

Russian schoolteacher and the founding father of theoretical rocketry - one of the three pioneers of astronautics alongside Robert Goddard and Hermann Oberth.

He lost his hearing at age 9 (scarlet fever) and was refused admission to school, so he taught himself. As a schoolteacher in Kaluga - 150 km from any major centre - he built Russia's first wind tunnel in his apartment and, in 1903, derived the rocket equation: the speed a rocket can reach depends only on exhaust velocity and the mass ratio. Decades before the first rocket flew he had also worked out multistage rockets, steering thrusters, space stations, airlocks - and, in 1895, inspired by the Eiffel Tower, the space elevator. He never built a rocket (Goddard flew the first liquid-fuel one in 1926), but his equation is the entire budget of every rocket ever flown, and his writings inspired von Braun, Korolev and Glushko.

Built on Jules Verne's fiction and 19th-century thermodynamics. Enabled the rocket-equation card and, through the engineers who read him, the whole space age: Sputnik, Vostok and the Saturn V all flew on his math.