Krafft Arnold Ehricke

Contributions to space flight dynamics Ehricke was well known in the field of astrodynamics and its applications; he published two-volume textbook Space Flight in 1959. It focuses on methods for exploration of the Solar System. Although he was not the first, he clearly demonstrated the so-called "gravity assist" method for using hyperbolic encounters with an intermediate planet to increase (or decrease) the velocity and orbital elements of a space vehicle. This technique was essential for the exploration of the Solar System. Examples include the Voyager missions to the outer planets and the recent New Horizons mission to Pluto. His contribution to this important field of exploration has been neglected for many decades and incorrect claims of the "invention" of gravity assist were made by Michael Minovitch.

Extraterrestrial Imperative Ehricke promoted a philosophical concept called the "Extraterrestrial Imperative." This idea refers to Ehricke's belief that it was the responsibility of humanity to explore space and exploit the resources of the Solar System, in order to sustain the development of the species. There are no external "limits to growth," Ehricke insisted, because while the Earth is a "closed system," the exploration of space opens the universe to humanity. For Ehricke, human creativity has no limits.