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Subject: A.L. Turkevich, Scientist Who Ascertained Moon's Makeup

Sept 7
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Date Posted: September 21, 2002 10:43:26 EDT

Anthony L. Turkevich, a scientist who was the first to figure out what the moon is made of and who did it before astronauts brought back any samples died on Sept. 7 at his home in Lexington, Va. He was 86.

Before Neil Armstrong landed on the moon in 1969, NASA sent several unmanned spacecraft to scout it. Aboard Surveyor 5, which landed on the Sea of Tranquillity in 1967, was Dr. Turkevich's alpha scattering spectrometer, a box about six inches to a side, which was lowered to the surface with a nylon string.

The instrument bombarded the moon's surface with subatomic particles from capsules of the radioactive element curium, the first use of this technique. After observing how the particles bounced off elements in the soil, Dr. Turkevich and his team concluded that the surface was made of the volcanic rock basalt with a high degree of titanium. The lunar soil was similar to that of the Hudson River Palisades. Two later craft, Surveyors 6 and 7, also carried Dr. Turkevich's spectrometer.

Because of the high titanium findings, his results were greeted with widespread skepticism. But Dr. Turkevich was vindicated when the moon rocks brought back by Apollo 11 confirmed his discovery.

For the Mars Pathfinder mission in 1997, Dr. Turkevich and colleagues adapted his instrument into the Alpha Proton X-Ray Spectrometer, which analyzed rocks given fanciful names like Scooby-Doo and Yogi. It found that Mars and Earth were made up of similar materials, but in different proportions. The spectrometer will be carried next year on two more missions to Mars, said Thanasis Economou, a colleague of Dr. Turkevich at the Enrico Fermi Institute of Nuclear Studies at the University of Chicago.

In World War II, Dr. Turkevich worked for the Manhattan Project, which built the atomic bomb, studying gaseous diffusion and measurements of radioactive fallout.

After the war, he worked on the hydrogen bomb project, performing a calculation that demonstrated that such a bomb was not impossible. Dr. Turkevich conducted highly classified work concerning nuclear technology in the Soviet Union, and developed techniques to measure the spread of gases globally, according to Dr. George A. Cowan, senior fellow emeritus at Los Alamos National Laboratory. But in 1969 he also won the Atoms for Peace Award, given to scientists who develop ways to use atomic energy for peaceful purposes.

He worked with the physicist Enrico Fermi to calculate the proportion of the elements generated in the Big Bang, concluding that it was 25 percent helium to 75 percent hydrogen.

Anthony Leonid Turkevich was born on July 23, 1916, at the bishop's house attached to St. Nicholas Russian Orthodox Cathedral on East 97th Street in Manhattan. His father, as Metropolitan Leonty, became the primate of the Russian Orthodox Church in the United States.

Dr. Turkevich earned his bachelor's degree from Dartmouth and his doctorate from Princeton, both in chemistry. After the war, he worked at the University of Chicago until he became professor emeritus in 1986. He was elected to the National Academy of Sciences in 1967.

He is survived by his wife of 53 years, Ireene; a son, Leonid, of Alpharetta, Ga.; a daughter, Darya Carney of Grand Rapids, Mich.; a brother, Nicholas, of West Fairlee, Vt.; and three grandchildren.

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