Distributed August 23, 2001
For Immediate Release
News Service Contact: Janet Kerlin



Our solar system’s oldest raw materials

Brown scientists identify Tagish Lake meteorite’s origin in space
The well-preserved Tagish Lake meteorite has been identified as coming from a D-type asteroid, confirming that it contains the oldest raw materials among asteroids in the solar system. The study by Brown geologists Takahiro Hiroi and Carle Pieters and a colleague from NASA shows that the meteorite fell from the mid-to-far end of the asteroid belt between Mars and Jupiter. The study was published by the journal Science, within the “ Science Express” Web site.

PROVIDENCE, R.I. — Brown geologists Takahiro Hiroi and Carle Pieters and a colleague from NASA have identified the location from which an unusually well-preserved meteorite fell – the mid-to-far end of the asteroid belt between Mars and Jupiter. Their results confirm that the Tagish Lake meteorite is made of probably the oldest materials in the solar system.

To the amazement of observers, the fireball fell in northern British Columbia in January 2000. The event was photographed, recorded by satellites, and resulted in hundreds of fragments being collected from a frozen lake. The meteorite was probably the size of van, but broke into fragments that were preserved in ice from the lake.

Hiroi, Pieters and Michael Zolensky of NASA’s Johnson Space Center in Houston are the first to identify the carbon-rich meteorite as having broken off from a D-type asteroid, the kind that most scientists acknowledge contains the oldest raw materials among asteroids. Their results were published by the journal Science, within the “ Science Express” Web site, on Aug. 23, 2001.

Their method, reflectance spectroscopy, provides an optical fingerprint showing a meteorite’s composition. Data is obtained by measuring the amount of reflected light as wavelength is changed from visible to near-infrared.

Their study provides clues in determining the formation of the solar system 4.6 billion years ago. The research was funded by grants from NASA.

A second article on the “Science Express” Web site details the organic content of the Tagish Lake meteorite. Brown assistant professor Yongsong Huang is a co-author with lead investigator Sandra Pizzarello of the Arizona State University Chemistry Department.

At Brown, the researchers used state-of-the art technology to measure the isotopic composition of individual compounds. The findings provide insight to an outcome of early solar chemical evolution that differs from any seen in meteorites so far.

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