Dec. 1, 2006 — Scientists have known for years that meteorites and comets contain organic matter, bolstering theories of a cosmic origin for life. Now, they may have discovered what could be the transport system.
After cutting into and thoroughly analyzing samples from a freshly fallen meteorite, researchers found tiny hollow spheres made of organic material that predates the birth of the solar system.
"It is not a new idea that a lot of organic matter on Earth originally came from meteorites and comets," said Scott Messenger, a NASA scientist at the Johnson Space Center in Houston who studies the isotopic chemistry of extraterrestrial materials.
"What is new here is that we have identified a new physical form of the matter and the source."
Of particular interest to astrobiologists, he added, is the shape of the globules.
"They're not all that different in shape from cells and they're hollow, which is a good structure for protecting the earliest life forms," he said.
One reason why Messenger and his colleagues believe they were able to find the globules is that the meteorite is one of the few that was seen falling to the Earth and recovered in a relatively short time.
Residents of western Canada saw the meteorite arriving as a brilliant fireball in the Yukon sky on the morning of January 18, 2000. Chunks of the meteorite were soon found embedded in the ice of Tagish Lake in Ontario.
The snow- and ice-covered lake essentially froze the meteorite and kept it from becoming contaminated.
"It was a clean place to fall and it was collected very carefully," Messenger said.
The type of meteorite in which the globules were found is fragile and typically breaks up into dust during its entry into Earth's atmosphere.
"If, as we suspect, this type of meteorite has been falling onto Earth throughout its entire history, then the Earth was seeded with these organic globules at the same time life was first forming here," said Mike Zolensky, a NASA cosmic mineralogist and co-author of a paper about the meteorite appearing in this week's issue of Science.
Messenger's wife, Keiko Nakamura-Messenger, the lead author of the study, is credited with finding the globules and bringing them to the attention of her husband and others to chemically analyze.
