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Adriana C. Ocampo: 1955—: Planetary Geologist

Ejecta Studies Led To New Discoveries

The second new ejecta site in Belize contains tiny green glass spheres called tektites—rocks that were melted by the heat of the impact. The team collected about 900 pounds (400 kilograms) of samples and drill cores for paleomagnetic studies, as well as fossils to help date the site. Among their fossils was a new species of crab from the Late Cretaceous and a new species of gastropod. With sponsorship from TPS, Ocampo led further geological expeditions to Belize in January of 1995, 1996, and 1998. In 1996 she co-led a TPS expedition to Gubbio in Italy, to drill at the original discovery site of impact ejecta at the K/T boundary.

Ocampo has given numerous presentations on her Chicxulub research at universities and professional meetings. Scientists now believe that the Chicxulub crater was formed by the impact of an asteroid or comet that was six to eight miles (10 to 14 kilometers) in diameter. Since the impact rock is very rich in sulfur, it is postulated that the impact resulted in a global sulfuric acid cloud that caused the Earth's atmosphere to remain opaque for about 10 years. Ocampo earned her master's of science degree in geology from California State University at Northridge in 1997 with a thesis on the Chicxulub impact crater. She was awarded a grant by NASA to continue her research on the impact's effects on Earth's biosphere and its relation to the mass extinction.

In 1996 Ocampo presented her team's discovery of a chain of impact craters in the central African nation of Chad. The craters were found using radar images taken by the Spaceborne Imaging Radar C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) mounted on the space shuttle Endeavor in 1994. Ocampo told the JPL press office, "The Aorounga craters are only the second chain of large craters known on Earth, and were apparently formed by the break-up of a large comet or asteroid prior to impact. With ground confirmation, this second chain will provide valuable data on the nature and origin of small bodies that cross Earth's orbit." The craters are believed to have been formed by an asteroid or comet that was about one-tenth the size of the one that formed the Chicxulub crater.

The study of impact craters has become important for understanding how the Earth and solar system formed and how life has evolved. Ocampo estimated that the Chad craters are about 360 million years old, corresponding to another period of mass biological extinctions. Ocampo told JPL, "These impacts in Chad weren't big enough to cause the extinction, but they may have contributed to it. Could these impacts be part of a larger event? Were they, perhaps, part of comet showers that could have added to the extinction? Little by little, we are putting the puzzle together to understand how Earth has evolved."

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Brief BiographiesBiographies: Grace Napolitano: 1936—: Politician to Richard (Wayne) Peck (1934-) Biography - CareerAdriana C. Ocampo: 1955—: Planetary Geologist Biography - Joined Jpl As A Teenager, Worked On Numerous Planet Mapping Projects, Studied The Chicxulub Impact Crater