Rare Meteorites Challenge Theories on Origins of Life

(May 6) -- Earth is constantly being showered with extraterrestrial rocks and dust. The vast majority of these fragments of asteroids and comets are far too small to do any damage -- but they can contain valuable scientific information, including clues to the evolution of the solar system and potentially the origins of life on Earth. That is, if you can find a good one first.

A team of researchers led by Jean Duprat of the French National Center for Scientific Research did just that, and in this week's issue of the journal Science, they describe the discovery and analysis of the two incredibly rare space rocks they have been studying.

What the scientists found from the rocks could change established ideas about where some of the basic ingredients for life on Earth formed, and how they made their way to our planet, according to Carnegie Institution cosmochemist Larry Nittler, who was not affiliated with the project. "These samples provide one more clue to the starting conditions," Nittler tells AOL News. The rocks, Nittler adds, could also fill out scientists' picture of the early solar system. "Basically," he says, "it just makes the whole situation more complex."

Duprat and his colleagues have been sifting through the Antarctic snow, which preserves these space rocks better than other sites, for years. They carefully remove the grains they find in the snow, bring them back to the lab for analysis, and determine which ones are of extraterrestrial origin. Then they study these micrometeorites in more detail, searching for interesting or surprising features.

In this case, the two rocks were rich in organic matter. This isn't significant on its own -- numerous extraterrestrial rocks contain the basic ingredients of life. The surprise relates to their origin. These materials are supposed to originate outside our solar system, in the vastness of interstellar space, but Duprat and his group found evidence within the rocks to suggest otherwise. "We've been able to analyze the little minerals that are closely associated with the organic matter," Duprat tells AOL News, "and they are typical of the protoplanetary disk, the disk that was within the solar system at the time of its formation." That suggests the organic materials probably formed right here, in our own solar system, and not out in interstellar space.

According to Nittler, surprising details like this help clarify our cosmic history. "We know the solar system started as this disk of gas and dust," he says, "and we want to know what the starting conditions were, and what happened to that material -- how it was moved around, how it got incorporated into planets."

Though he favors the idea that they formed within the solar system, Duprat says the precise origin of the organic matter is still an open question. The next step for him and his group, though, is far more clear. "We got very few of them because the grains we are talking about are extremely rare," he says. "We will definitely go back to Antarctica for more."