Die Erreichbarkeit der Himmelskörper by Hohmann, Walter - 1925

Munich: R. Oldenbourg, 1925. Hohmann, Walter (1880-1945). Die Erreichbarkeit der Himmelskörper. [2], iv, [2], 88pp. Text diagrams. Munich and Berlin: R. Oldenbourg, 1925. 225 x 180 mm. Original tan printed wrappers, light wear at spine. Minor faint foxing, but very good. First Edition, variant with tan printed wrappers (the work was also issued in dark blue wrappers with a pictorial design in white). Hohmann discovered what is now called the "Hohmann transfer orbit," an orbital maneuver using two engine impulses to move a spacecraft between two coplanar orbits. This maneuver, described in Hohmann's Die Erreichbarkeit der Himmelskörper, uses a minimum-energy trajectory consisting of an ellipse tangent to the two orbits; this is the most fuel-efficient path for moving a spacecraft between two different orbits. "Walter Hohmann's great contribution to astronautical progress was the discovery of a new use for an old object, the ellipse. However, his involvement in the development of concepts for space travel extended well beyond that discovery: energy and mass requirements; spacecraft design; atmospheric modeling; maneuver analysis; crew safety; extraterrestrial in-situ propellant production, and more. In addition to conducting research, Hohmann belonged to Verein für Raumschiffahrt (Society for Space Travel), or VfR, and participated in its work" (McLaughlin, "Walter Hohmann's roads in space," Journal of Space Mission Architecture (Fall 2000): 1-14.