Kondratiuk, Yurii [Кондратюк, Юрій; Kondratjuk, Jurij; real name: Oleksander Sharhei], b 21 June 1897 in Poltava, d October 1941 in Kozelsk raion, Kaluga oblast, Russian Soviet Federated Socialist Republic. Scientist and inventor; pioneer in rocketry and space technology. After studying at the Saint Petersburg Polytechnical Institute, he worked at various plants in Ukraine, Russia, Kuban, Northern Caucasia, and Siberia. From 1933 he headed a task force at the Ukrainian Scientific Research Institute of Industrial Power Engineering in Kharkiv designing the largest wind-powered electric station in the world. In 1919 he published Tem, kto budet chitat', chtoby stroit' (To Those Who Will Read in Order to Build), which was expanded into Zavoievanie mezhplanetnykh prostranstv (The Conquest of Interplanetary Space, 1929). In this work Kondratiuk developed the basic equations for rocket motion, calculated optimal flight trajectories, explained the theory of multistage rockets, and advocated the use of new rocket fuels, including the boron fuels used today. He proposed that orbiting supply bases be used to supply spacecraft, that atmospheric drag be used for braking descending spacecraft, that small excursion vehicles be used to land men on planets and return them to spaceships, and that the gravitational fields of celestial bodies be used for accelerating and braking spaceships. Kondratiuk’s ideas and equations are used widely today by Russian, American, and other space engineers. The National Aeronautic and Space Administration has translated his work into English and has used many of his concepts in the Apollo moon flights. One of the craters on the far side of the moon is named after him. During the Second World War he reportedly was drafted into the army and died under undisclosed circumstances. The Yurii Kondratiuk Museum of Aviation and Space Exploration (a branch of the Poltava Regional Studies Museum), with an exhibit dedicated to Kondratiuk, was established in 1988.

Lubomyr Onyshkevych

[This article originally appeared in the Encyclopedia of Ukraine, vol. 2 (1988).]