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Scientists have studied bubble-like globules in the freshest meteorite ever discovered and believe it may help us to determine the way life evolved from organic compounds to living cells.
The study was performed on a meteorite found in January 2000 on top of a frozen lake in Canada, known as Tagish Lake. The meteorite is classified as a carbonaceous chondrite, - a rare variety that is rich in organic (carbon-bearing) compounds.
These meteorites are of particular interest to scientists because their organic material formed at the dawn of the Solar System. These organic compounds may even have brought the building blocks of life to Earth.
The Tagish Lake meteorite is especially valuable because most of its pieces were collected immediately after it fell though the atmosphere. In space these rocks are extremely cold, but once they land on the Earth�s surface they gradually warm up. The Tagish Lake meteorite, however, was collected and maintained in a frozen state, minimizing any contamination from the Earth.
The team studying the object, headed by NASA space scientist Keiko Nakamura-Messenger, reports that the Tagish Lake meteorite contains many tiny hollow �bubbles� known as globules. Similar features have been spotted in other meteorites over the past five decades with some scientists believing the globules were space organisms and others thinking they were caused by Earth contamination.
The globules had been very difficult to study because of their size, but now a new instrument at the Johnson Space Center, Houston, USA, can help scientists analyse them much more easily. They found that the composition of the globules proved they did not come from Earth. In fact the results showed that the �bubbles� formed at around minus 260 degrees, near absolute zero, suggesting they formed in the outermost reaches of the Solar System, or even before our Solar System was �born�!
"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 of NASA and co-author of the paper.
Whilst these compounds are extremely basic compared to living cells, some scientists believe they are �a step in the right direction� to making a cell wall. If so then they could provide clues about how life developed from a few organic compounds to the great variety of organisms that exist today.
The research was published in the 1 December issue of Science.
More info: Science
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