Liquid-propellant rocket
The idea of liquid rocket as understood in the modern context first appears in the book The Exploration of Cosmic Space by Means of Reaction Devices, by the Russian school teacher Konstantin Tsiolkovsky. This seminal treatise on astronautics was published in May 1903, but was not distributed outside Russia until years later, and Russian scientists paid little attention to it. The first flight of a liquid-propellant rocket took place on March 16, 1926, when American professor Dr. Robert H. Goddard launched a vehicle using liquid oxygen and gasoline as propellants.
