Discoveries
Rutgers research that made the news this summer
Archived article from Oct 8, 1999
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A meteoroid is a natural object moving through interplanetary space, as opposed to a meteorite, which is what the object is called after it has fallen to Earth.
The team, which included Rutgers chemists Christoph Schnabel and Gregory Herzog together with colleagues in Arizona, California and Australia, used ultrasensitive measurements and computer modeling to gain insight into meteoroid dynamics.
"Two types of material survive from the Canyon Diablo impactor -- iron meteorites, which did not melt during the impact, and spheroids, which did," said Herzog, professor of chemistry at the Faculty of Arts and Sciences-New Brunswick. "Our challenge has been to determine the processes involved in the impact and the formation of the resulting products, specifically the spheroids -- millimeter-size fragments found in the soils around the crater."
In the July 2 issue of Science, the authors describe how they were able to deduce the original depth within the body of the meteoroid of the material that melted to form the spheroid droplets. The group employed accelerator mass spectrometry to analyze a rarely measured radioisotope of nickel, known as a cosmogenic nuclide, that was produced by cosmic ray bombardment in the outer shell of the meteoroid while in space. The relative concentration of this nuclide serves as a good indicator of depth of origin of the spheroid fragments.
The resulting depth figures were then compared with predictions from computer-modeled simulations of the impact. Conclusions based on this comparison yielded new information about the dynamics of meteoroid strikes on Earth, information that may be applied in general to other impacting medium-size meteoroids.
For example, the researchers were able to conclude that the trailing hemisphere of the meteoroid melted in the impact blast and gave rise to the spheroids. They further assert that material in the leading hemisphere of the meteoroid would more readily have mixed with and been lost in a large volume of rock at the impact site.
-- Joseph Blumberg
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