Konstantin Eduardovich Tsiolkovsky
Theoretician of space travel
'The Probing of Space by Means of Jet Devices' (1903)
which propounded the idea of multistage liquid-fuel rockets for space travel.
"Man will not always stay on Earth;
the pursuit of light and space
will lead him to penetrate the bounds of the atmosphere
timidly at first but in the end to conquer
the whole of solar space."