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Harold Urey’s Many Contributions to Science

by Kathy Chambers on Tue, May 16, 2017

Harold C. Urey

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To celebrate 70 years of advancing scientific knowledge, OSTI is featuring some of the leading scientists and works particularly relevant to the formation of DOE, OSTI, and their predecessor organizations and is highlighting Nobel laureates and other important research figures in DOE’s history.  Their accomplishments were key to the evolution of the Department of Energy, and OSTI’s collections include many of their publications. 

The pioneering work of American chemist and physicist Harold C. Urey on isotopes led to his discovery of deuterium in 1931 and earned him the 1934 Nobel Prize in Chemistry.  This discovery was one of his many contributions in several fields of science during his long and diverse career. 

By 1929, the theory of isotopes, or the idea that an individual element could consist of atoms with the same number of protons but with different masses, had been developed, and the less-abundant isotopes of carbon, nitrogen, and oxygen had been discovered.  Urey, who at the time was an associate professor at Columbia University, believed that isotopes of hydrogen could be more important, so he devised an experiment to look for them.

In 1931, Urey was credited with discovering the hydrogen isotope, or heavy hydrogen, for which he subsequently won the Nobel Prize; he later named the heavy hydrogen “deuterium,” derived from the Greek word deuteros meaning “second,” which denotes the two particles composing deuterium’s nucleus.  Practical applications for deuterium included replacing hydrogen in water molecules to produce “heavy water,” used as a moderator in nuclear reactions and tracing biochemical reactions in living tissues.  Urey became recognized as the leading authority on isotopes.  He went on to isolate heavy isotopes of carbon, nitrogen, oxygen, and sulfur, and by 1939, he and his associates had developed methods to separate the rarer isotopes of all of these elements to use in laboratory research.  The isolation of deuterium was a significant contribution to science and opened a world of future discovery. 

During World War II, Urey was tapped to be head of isotope separation and heavy water research for the Manhattan Project, where he served on various advisory committees and led a team of 700 scientists, engineers, and technicians to develop a diffusion method to separate the uranium-235 isotope from uranium-238 for use in the atomic bomb.  His major contribution to the wartime effort was the gaseous diffusion process used to produce enriched uranium.  Urey later went on to encourage the control of nuclear arms and investigate the peaceful uses of nuclear fission.

After the war, Urey’s research focus changed to geochemistry and planetary sciences, and his contributions to science continued.  He pioneered methods of calculating how the temperature of our atmosphere changes over time.  This research led him to develop the field of “cosmochemistry,” which deals with the relative abundance of elements on Earth and how they evolve in our universe.  Urey and his graduate student Stanley Miller carried out a landmark experiment replicating Earth’s early environment, where earth’s primordial ingredients could have been forced by lightning discharges to create the basic chemicals of life.  Electric sparks were passed through a chemical solution of methane, ammonia, hydrogen, and water, which resulted in the formation of four amino acids, the building blocks of life.  This discovery led Urey to conclude that life could evolve on other planets under the right conditions.  Subsequent research on the origin of life has been greatly influenced by this experiment.    

Later in his life, Urey’s interest turned to lunar research, and he made major contributions to space exploration.  He helped influence the National Aeronautics and Space Administration (NASA) to undertake the Apollo program of lunar exploration, and he was involved as an advisor and consultant.  Urey became the namesake of the Urey Prize of the American Astronomical Society, a Mars exploration instrument, an asteroid, and a lunar crater. 

Honors for Urey’s contributions to science were also numerous.  In addition to his Nobel Prize in Chemistry, he received his profession’s highest honors, 25 honorary doctorates, the Medal for Merit from President Harry S. Truman for his World War II work, and the National Medal of Science from President Lyndon B. Johnson for his space program work.   

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Page last updated on 2017-09-08 08:00

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Kathy Chambers
Technical Writer, Information International Associates, Inc.