John Aloysius O'Keefe III (October 13, 1916 – September 8, 2000) was an expert in planetary science and astrogeology with the National Aeronautics and Space Administration (NASA) from 1958 to 1995.
He and his co-authors, Ann Eckels and Ken Squires, are credited with the discovery that the Earth had a significant third degree zonal spherical harmonic in its gravitational field using U.S. Vanguard 1 satellite data collected in the late 1950s.
His first major discovery, while in graduate school (1938), was that clouds of solid carbon cause the peculiar dips in the light curve of R Coronae Borealis, the archetype of a class of carbon-rich stars.
O'Keefe joined NASA in December 1958 and became the assistant chief of the Theoretical Division under Robert Jastrow at the Goddard Space Flight Center in Greenbelt, Maryland.
After the Moon landings his claim was apparently supported by a chemical analysis of a portion of lunar sample 12013 retrieved by Apollo 12 astronaut Pete Conrad that showed a similar major element composition to some tektites found in Southeast Asia.
However, most other lunar data strongly challenged the O'Keefe hypothesis, and almost all researchers in this field now accept that tektites are of terrestrial origin, the products of large meteorite or cometary impacts on Earth.
This is supported by geochemical, isotopic and mineralogical evidence, and the fact that most tektite strewn fields can now be confidently matched to known impact craters of similar age on Earth.
[6] O'Keefe died on September 8, 2000, in Sioux Falls, South Dakota, from complications of liver cancer and Parkinson's disease.