"It's extremely friable"—easily pulverized—"and the material breaks up very easily."
The object's fragile nature is one of the clues that led some scientists to theorize that Tagish Lake could be the most primitive meteorite ever discovered.
"By primitive we don't mean the oldest chronologically," explained Brown, who is not involved with the Science study.
"We mean that the material in the meteorite has been processed the least since it was formed. The material we see today is arguably the most representative of the material that first went into making up the solar system."
The meteorite likely formed in the outer reaches of the asteroid belt, but the organic material it contains probably had a far more distant origin.
The globules could have originated in the Kuiper Belt group of icy planetary remnants orbiting beyond Neptune. Or they could have been created even farther afield.
The globules appear to be similar to the kinds of icy grains found in molecular clouds—the vast, low-density regions where stars collapse and form and new solar systems are born.
Links to Life?
Some scientists speculate that organic matter arriving via ancient meteorites and comets are responsible for the rise of life on Earth.
(Related news: "Building Blocks of Life Found in Two Meteorites" [December 19, 2001].)
The unique shape of the newfound globules could be of particular interest to supporters of this theory.
The structures are invisible to the naked eye and resemble minute hollow balls with carbon-rich shells. A chunk of meteorite no larger than a grape could contain a billion of the tiny globules.
Theoretically, their hollow-ball shape could have presented a homey environment of concentrated organic matter where early cellular life could develop.
Such theories boast little evidence but raise many intriguing questions.
"We don't claim that these things are alive or anywhere close to being alive," NASA's Messenger cautioned.
"But the fact is that this material fell down on Earth, and similar if not identical material has been falling onto the Earth for its entire history.
"Understanding the origins of that matter is inherently tied in with understanding the origins of life."
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