Hermann Julius Oberth was an Austro-Hungarian-born German physicist and rocket pioneer of Transylvanian Saxon descent. He is considered one of the founding fathers of rocketry and astronautics, along with Robert Esnault-Pelterie, Konstantin Tsiolkovsky, Robert H. Goddard and Herman Potočnik. Oberth supported Nazi Germany's war effort and received the War Merit Cross in 1943.

A rocket is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely from propellant carried within the vehicle; therefore a rocket can fly in the vacuum of space. Rockets work more efficiently in a vacuum and incur a loss of thrust due to the opposing pressure of the atmosphere.