Earth Science - Other

When is the next Meteorite going to Hit Earth



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The Tagish Lake meteorite which fell over Canada in 2000 has provided NASA researchers at the Johnson Space Center in Houston with a golden opportunity to study organic materials created in the far distant areas of our early solar system. The meteorite is of a rare type which has abundant organic compounds. Interest in meteorites containing carbon is high since the compounds were created at the beginning of the solar system and might possibly have sown the Earth with the raw material from which life emerged. The meteorite was collected immediately after it fell and has been kept frozen to lessen the chance it would be contaminated with material from the Earth.

The head of the NASA group studying the meteorite, Keiko Nakamura-Messinger has revealed the presence of numerous submicrometer hollow globules. Although these objects have been noted in a number of meteorites since the 1960s,there was disagreement among scientists as to whether they were actually space organisms or a result of terrestrial contamination.

While studying the Tagish meteorite researchers had a very fresh meteorite to examine as well as improved technology to better analyze the material. New nano-technology instruments became available in 2005 to researchers at the Johnson Space Center, which made it possible to study extremely thin slices of the meteorite with a new JEOL transmission electron microscope that provided detailed data about the structure and chemistry of the globules. Subsequently, the globules were analyzed with a new mass spectrometer, the Cameca NanoSIMS, the first instrument of its kind to make this important measurement on such minute objects in order to determine their isotopic composition.

The globules isotopic ratios indicate they were created in very low temperatures of about -260 C or absolute zero, and were probably formed in the cold molecular cloud from which our solar system was formed or at the most remote areas of the early solar system.

The meteorites which contain these globules are very fragile and usually do not survive the trip through the planet's atmosphere, and breaking up in the atmosphere results in the organic matter contained in the meteorite being spread across the surface of the Earth. If this type of meteorite has been impacting the Earth from the time of its formation, then the planet was being seeded with organic material at the time when life was beginning. The globules are also significant in that some biologists suggest that making a bubble-shape is the first step toward the creation of biotic life.

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