John A. O'Keefe
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John A. O'Keefe (1916 - 2000) was a planetary scientist with the National Aeronautics and Space Administration (NASA) from 1958 to 1995. He is credited with the discovery of Earth's "pear shape" using U.S. Vanguard satellite data collected in the late 1950s. He was the first to propose the idea of a scanning microscope in 1956 and he was the co-discovery of the YORP effect (short for Yarkovsky-O’Keefe-Radzievskii-Paddock),an effect resulting from sunlight which causes a small celestial body such as an asteroid or meteor to spin up or down.
During the early Project Apollo-era, O'Keefe was one of the major leaders in developing the American lunar science program and was instrumental in securing astrogeologist Eugene Shoemaker to work with NASA in developing a geology program for the Apollo astronauts. O'Keefe demonstrated that tektites, meteorite-like natural glass objects found around the world, are actually volcanic ejecta from the Moon. He based part of his claim on the chemical analysis of a portion of lunar sample 12013 retrieved by Apollo 12 astronaut Pete Conrad that was nearly identical with some tektites found in southeast Asia.
O'Keefe suggested explosive, hydrogen-driven lunar volcanoes as the original source of tektites. Since the unmanned U.S. Clementine mission to the Moon during the 1990s, vast areas of pyroclastic (volcanic) glasses have been indentified, notably in the area of the Aristarchus plateau. There is also evidence of interstitial granitic material (akin to the acidic tektites in chemistry) in some lunar highland samples which bolsters O'Keefe's lunar-origin theory.
Lunar Orbiter spacecraft images reveal fields of volcanic domes that indicate deep-seated, high-silica eruptions on the Moon, possible sources of the tektites as predicted by O'Keefe. These lunar domes are similar to the Mono Lake craters (Mono-Inyo Craters) of California; curiously, Mono obsidians resemble some layered tektites on the macroscopic level.
[edit] References
- Gray, M. Angle of Attack: Harrison Storms and the Race to the Moon. W.W. Norton, New York: 1992.
- O'Keefe, J.A. (June 5, 1970) Tektite glass in Apollo 12 sample. Science, Vol 168, 1209–1210.
- O'Keefe, J.A. (Feb. 26, 1985) The coming revolution in planetology. Eos, Vol. 66, No. 9, pp. 89–90.
- O'Keefe, J.A. (1993) The origin of tektites. Meteoritics, Vol. 29, No. 1, pp. 73–78.
- O'Keefe, J.A. (1976) Tektites and their origin. Elsevier.
- Povenmire, H., O'Keefe, J.A., ed. (2003) Tektites: A cosmic paradox. Florida Fireball Network.
- Varricchio, Louis (fall 2006) Inconstant Moon: Controversy and Discovery on the Way to the Moon. Xlibris-Labyrinth Books.
