Walter Hohmann

Walter Hohmann (March 18 1880 - March 11 1945) was a German engineer who made an important contribution to the understanding of orbital dynamics. In a book written in 1916 (published 1925), Hohmann demonstrated a very fuel-efficient path to move a spacecraft between two different orbits, now called a Hohmann transfer orbit.

Hohmann was born in Hardheim, the son of a doctor. Whilst a boy, he lived with his family in Port Elizabeth, South Africa for a time, before returning to Germany. He studied civil engineering at the Technical University of Munich, graduating in 1904. He then worked for the municipal councils of Vienna, Hanover and Breslau before settling in Essen, where he eventually held the post of chief architect.

Between 1911 and 1915, Hohmann devoted himself to the problem of interplanetary spaceflight, calculating the requirements of sending a spacecraft from Earth to one of the nearby planets of the solar system. He realised that minimising the amount of fuel that the spacecraft had to carry would be an important consideration, and plotted a variety of orbits until he found the one that now bears his name. He published his findings in Die Erreichbarkeit der Himmelskörper (The Attainability of the Celestial Bodies).

The importance of this work saw Hohmann become a leading figure in Germany's amateur rocketry movement in the late 1920s, the Verein für Raumschiffahrt (VfR - "Spaceflight Society"). Following the rise to power of the Nazi government, Hohmann distanced himself as much as possible from rocketry, wishing to play no part in the development of the rocket as a weapon.

He died in an Essen hospital shortly before the end of World War II as a result of stress experienced during the intense Allied bombing of the city.