Purdue News

February 5, 1992 Antarctic Meteorites Provide Clues To How Solar System Formed CHICAGO — Meteorites found in Antarctica may be one of mankind's most direct links to the beginning of our solar system, says a Purdue University researcher. "We can study the solar system or galaxies through telescopes or satellite images, but meteorites provide most of the samples we have of bodies outside the Earth," says Michael E. Lipschutz, professor of chemistry. "Because many of the Antarctic meteorites date back to the beginning of the solar system, they can provide valuable information on planetary evolution and properties." To aid in these studies, the Purdue group has established a new research facility for accelerator mass spectrometry — a sensitive and highly selective technique for measuring concentrations of rare isotopes. The facility is one of only a few of its type in the nation, and the only one dedicated to Earth and planetary sciences. Lipschutz is using the facility to initiate a major research program in chronological studies of planetary materials, including meteorites from Antarctica. Information from the studies will be used to develop a "map" relating the solar system materials to each other. He will present information on his studies of Antarctic meteorites Tuesday (2/11) during the American Association for the Advancement of Science annual meeting in Chicago. Most meteorites are pieces of asteroids that survive entry into the Earth's atmosphere. They are formed when asteroids collide in space with great force, scattering fragments throughout the universe and sending some pieces of rock hurling toward Earth. In general, meteorite discoveries are somewhat rare. Early explorers in Antarctica, however, found a treasure trove of the extraterrestrial materials. Since 1969, about 15,000 meteorites have been collected in Antarctica. The Antarctic collection includes some of the oldest meteorites ever found, many dating back billions of years. "By analyzing the chemical and thermal histories of these fragments, we can gain new insights into the history of our solar system and galaxy," Lipschutz says. The Antarctic meteorites also include many rare or unique fragments, including samples from the moon and Mars, and a wider sampling of near-Earth asteroids than do meteorites collected from other locations. "These meteorites are extremely diverse in their types and origins, allowing us to sample more of the solar system," he says. In addition, the Antarctic collection provides a snapshot of changes over time in the numbers and types of meteorites that have fallen to Earth, Lipschutz says. "The meteorites that have fallen within the past few hundred years are dramatically different from those that came to Earth 100,000 to 700,000 years ago," he says. "These findings suggest that the types of planetary bodies orbiting Earth may have changed over time." Though 100,000 years sounds like a long time to most people, Lipschutz notes that it is a very short period on a solar-time scale. "To think that our sample of solar-bodies have changed that much in a few hundred thousand years is astounding," he says. By understanding the origin of our solar system, Lipschutz says scientists can learn more about how other solar systems form and gain insights in how and where to search for them. Though meteorites provide only random pieces of heavenly bodies, scientists can use this information to assemble a meaningful pattern, like fitting pieces of a jigsaw puzzle together, he says. In his studies, Lipschutz analyzes trace elements, chemical elements that show up in extremely small amounts, to determine a meteorite's age and provide information on other events in its history. Purdue News Service: (765) 494-2096; purduenews@purdue.edu