Victor G. Szebehely (August 21, 1921 – September 13, 1997) was a key figure in the development and success of the

Apollo program The Apollo program, also known as Project Apollo, was the United States human spaceflight program led by NASA, which Moon landing, landed the first humans on the Moon in 1969. Apollo followed Project Mercury that put the first Americans in sp ...

. In 1956, a dimensionless number used in time-dependent unsteady flows was named "Szebehely's number," (In the September and October 1977 issues of the journal Celestial Mechanics, volume 16, an equation used to determine the

gravitational potential In classical mechanics, the gravitational potential is a scalar potential associating with each point in space the work (energy transferred) per unit mass that would be needed to move an object to that point from a fixed reference point in the ...

of the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

planet A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

s, and

galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar Sys ...

was named " Szebehely's equation"). He worked with

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, the

Royal Netherlands Navy The Royal Netherlands Navy (, ) is the Navy, maritime service branch of the Netherlands Armed Forces. It traces its history to 8 January 1488, making it the List of navies, third-oldest navy in the world. During the 17th and early 18th centurie ...

, the

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, and the

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. One of his areas of research was orbital debris and planetary defense against

meteor impact An impact event is a collision between astronomical objects causing measurable effects. Impact events have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effe ...

s His first book, ''The Theory of Orbits'', is an important work in

orbital mechanics Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to rockets, satellites, and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and the law of universal ...

, being the definitive text on the

restricted three-body problem In physics, specifically classical mechanics, the three-body problem is to take the initial positions and velocity, velocities (or momentum, momenta) of three point masses orbiting each other in space and then calculate their subsequent trajector ...

as applicable to an Earth-

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

spacecraft A spacecraft is a vehicle that is designed spaceflight, to fly and operate in outer space. Spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth observation, Weather s ...

system such as

Apollo Apollo is one of the Twelve Olympians, Olympian deities in Ancient Greek religion, ancient Greek and Ancient Roman religion, Roman religion and Greek mythology, Greek and Roman mythology. Apollo has been recognized as a god of archery, mu ...

. He was knighted by

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of the

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in 1957.

History

Szebehely was born in

Budapest Budapest is the Capital city, capital and List of cities and towns of Hungary, most populous city of Hungary. It is the List of cities in the European Union by population within city limits, tenth-largest city in the European Union by popul ...

Hungary Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...

. His father was an engineer and he started to study in that field, but switched later to physics. In 1944 he graduated as an engineer from the Budapest University of Technology and Economics. Because of the threatening communist take over he went to the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

in 1947 and became a

naturalized citizen Naturalization (or naturalisation) is the legal act or process by which a non-national of a country acquires the nationality of that country after birth. The definition of naturalization by the International Organization for Migration of the ...

in 1956. Szebehely authored "Hydrodynamics of Slamming Ships" as David Taylor Model Basin Report 823 in 1952 and co-authored "Ship Slamming in Head Seas" as DTMB Report 913 in 1955. He was the author of several books. In 1978 he received the very first Dirk Brouwer Award from the Dynamical Astronomy Division of the

American Astronomical Society The American Astronomical Society (AAS, sometimes spoken as "double-A-S") is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC. The primary objective of the AAS is to promote the adv ...

. He died in

Austin, Texas Austin ( ) is the List of capitals in the United States, capital city of the U.S. state of Texas. It is the county seat and most populous city of Travis County, Texas, Travis County, with portions extending into Hays County, Texas, Hays and W ...

at age 76.

References

Hungarian physicists

External links

"In Memoriam - Victor G. Szebehely"
at the University of Texas at Austin
Interview with Victor G. Szebehely, July 20, 1988. University of Texas at San Antonio: Institute of Texan Cultures: Oral History Collection, UA 15.01, University of Texas at San Antonio Libraries Special Collections.
{{DEFAULTSORT:Szebehely, Victor 20th-century American astronomers Hungarian emigrants to the United States 20th-century Hungarian astronomers 20th-century Hungarian physicists Engineers from Budapest 1921 births 1997 deaths