WASHINGTON (AP) -- A bus-sized meteorite that blazed to Earth in a spectacular fireball in January could have delivered the most pristine primordial matter ever recovered from space and carry important new clues about the origin of life.
The meteorite, estimated to weigh 220 tons when it smashed into the atmosphere, shattered and sprayed bits of space rock over a frozen lake in Canada's Yukon Territory.
More than 70 eyewitnesses saw the fireball and a week later Canadian Jim Brook went out in sub-zero temperatures and found bits of the meteorite on the frozen surface of Tagish Lake. He collected the black, charcoal-like fragments in a plastic bag and stored them in a freezer, preserving them in a pure state.
Brook's careful handling will allow scientists to study matter that is virtually unchanged since the solar system formed some 4.6 billion years ago, said Peter G. Brown of the University of Western Ontario in London, Ontario, Canada.
"These are the most pristine meteorite specimens on the planet right now," said Brown, who is first author of a study appearing Friday in the journal Science.
Brook collected about two pounds of specimens. Expeditions in later months gathered some 410 additional fragments. But by then the material was beginning to weather away. The material is about the consistency of dried mud. Rain can cause it to crumble and wash away.
Preliminary tests of the pristine material find that it is loaded with organic molecules of the type that some experts have suggested could have been the original raw materials for the formation of life on Earth.
"Stuff like (the) Tagish Lake (meteorite) were pelting the early Earth," said Brown. "It is natural to assume that not only could organic molecules have been synthesized in the primordial soup on Earth, but they could have been brought here from an extraterrestrial origin."
The meteorite's fireball was detected by satellites, enabling Brown and other others to estimate the path of the space rock and backtrack it into space. They believe the object came from the asteroid belt, between the orbits of Mars and Jupiter. Brown said the object was probably jolted off a larger body and could have spent millions of years in orbit before being captured by Earth's gravity.
Bits of the meteorite have been distributed to a number of worldwide labs and researchers are painstakingly analyzing it. They are looking for amino acids and other organic compounds. A report on those studies may be a year away, Brown said.
When Michael E. Zolensky, a researcher at NASA's Johnson Space Center meteorite labs in Houston, thawed a bit of the material, he got a surprise.
"It had a strong sulfur smell," said Zolensky. That showed just how pristine the material is, he said, because the volatile chemicals that cause a sulfur smell are usually lost long before meteorite specimens get to a laboratory.
Lucy McFadden, a University of Maryland astronomer and asteroid expert, called the Tagish Lake meteorite "a treasure trove" for scientists and said it could "add a tremendous amount to our knowledge of extraterrestrial material and the origin of the solar system."
"This kind of finding makes one wonder about the origins of life -- was from the meteorites or did it just happen here?" said McFadden. "It is tantalizing."