NEW YORK: Scientists at NASA, who have studied the remains of the Tagish Lake meteorite that crashed into a frozen territory in Canada some seven years ago, say it might have hosted very early forms of life. The meteorite has been found to be rich in organic (carbon-bearing) compounds.
In a paper published in the current issue of the journal Science, the scientists, headed by NASA space scientist Keiko Nakamura-Messenger, say the meteorite contained numerous submicrometer hollow organic globules and these could be older than sun. These can offer an insight into the processes that were involved in creating planets and how life first came into existence.
Messenger said most of the meteorite's material is about the same age as our solar system -- about 4.5 billion years -- and was likely formed at the same time. But the microscopic organic globules that make up about one-tenth of one per cent of the object appear to be far older. Messenger and colleagues write that the isotopic anomalies in the globules indicate that they were formed in very cold conditions and believe these could not possibly have formed where the meteorite itself had formed.
The Tagish Lake meteorite, which appeared over the northern sky in January 2000, had burned up in the atmosphere and some pieces had fallen in Canada's frozen Yukon Territory and northern British Columbia. The retrieved parts have been maintained in a frozen state, avoiding terrestrial contamination.
Scientists believe the fragile nature of the meteorite could be an indication that it is the most primitive meteorite ever discovered. They feel the organic material it contained probably had a far more distant origin than the meteorite itself. The globules could have originated in the Kuiper Belt group of icy planetary remnants orbiting beyond Neptune, or even farther.
Messenger said the team does not claim that these things are alive or anywhere close to being alive. "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."
Though such organisms were present in other meteorites, the scientists could not identify them or study them because of several limitations. The new nano-technology instruments installed at the Johnson Space Center of NASA helped the scientists to first identify them in ultrathin slices of the meteorite. As they got the structural and chemical information about the globules, these were analyzed for their isotopic compositions. It was then found that they had very unusual hydrogen and nitrogen isotopic compositions, proving that the globules did not come from earth.
Messenger says the isotopic ratios in these globules show that they formed at temperatures of about -260 deg C, near absolute zero. "The organic globules most likely originated in the cold molecular cloud that gave birth to our Solar System, or at the outermost reaches of the early Solar System."
Organic matter in meteorites has been a keen subject of study among space scientists because this material is believed to have formed at the beginning of the solar system and may have provided the earth with its building blocks of life.
