Konstantin Tsiolkovsky (1857-1935), Russian scientist and inventor, a pioneer in rocket and space research. At the age of nine he lost his hearing almost completely and he studied mostly at home; he worked as a secondary school mathematics teacher until retiring in 1920. In the mid-1880s Tsiolkovsky began research in aerostatics, publishing articles containing plans for a metal dirigible (1892), an aeroplane (1894), and a spaceship (1903). During the 1920s he elaborated his theories of multi-stage rockets and of jet engines. He was made (1918) a member of the Soviet Academy. Among his books are Dreams of Earth and Sky (1895) and A Rocket into Cosmic Space (1903), in which he proposed the use of liquid propellants for spaceships. A crater on the Moon's far side is named after him.