About 470 million years ago – in a time period called Ordovician – the parent asteroid of one of the L chondrites, one of the most common meteorite types, was disrupted in a collision with another body. This event led to a subsequent bombardment of Earth with collisional debris for at least 10 million years. This finding is reported in a recent study in Earth and Planetary Science Letters by Field Museum scientists Dr. Birger Schmitz (Research Associate), Robert A. Pritzker Assistant Curator of Meteoritics and Polar Studies Dr. Philipp Heck, and an international team of coauthors.
Right after the Mifflin Meteorite fell in SW Wisconsin in April 2010 the Robert A. Pritzker Assistant Curator of Meteoritics and Polar Studies Dr. Philipp R. Heck coordinated an international study to determine the time it spent in space and to calculate its size in space before it got ablated and broke apart in our atmosphere. Now, first results obtained from this study are published as extended abstracts, and were presented in more detail in March at the Lunar and Planetary Science Conference in Texas: The new results show that Mifflin was travelling through space as a small 3 feet object for about 20 Million years before it landed in Wisconsin.
Private meteorite collector and Collections & Research Committee member Terry Boudreaux donated to the Field Museum two specimens of the iron meteorite Gebel Kamil that formed a 45-m-wide impact crater in the southwestern corner of Egypt (East Uweinat Desert) near the Sudanese and Lybian border. The crater was discovered through Google Earth in 2009 on a Cretaceous sandstone surface; the impact occurred less than 5000 years ago as reported in a recent article in Geology. The first meteorites were recovered in February. This exciting discovery was reported by the Italian-Egyptian group in the journal Science in August 2010. This first investigation indicates that the impactor did not suffer much during atmospheric entry and hit Earth almost fully intact. There are only about 200 confirmed impact structures on Earth.