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Building blocks of solar system detected

01 December 2006

Scientists have identified material they say came from a time before the creation of our solar system.

Particles from a meteorite reveal very unusual patterns of chemical composition that suggest they came from the material that formed our solar system. This is the oldest material ever identified at more than 4.5 billion years old.

'This is a fascinating piece of work,' says Dr Caroline Smith, meteorite expert at the Natural History Museum. 'This suggests these globules are some of the oldest objects discovered in meteorites.'

Ratios out of this world

NASA Scientists tested globules of carbon-rich material from the Tagish Lake meteorite to see whether they came from the meteorite itself or from elsewhere. They used electron microscopy and isotope tests and found unusual levels of different forms of nitrogen and hydrogen.

There were very high ratios of nitrogen 15 (N15) to nitrogen 14 (N14), nearly twice the levels on earth. They also found very high ratios of deuterium (the heavy form of hydrogen) to normal hydrogen, between 2.5 and nine times higher than on earth. Extremely cold temperatures would have been essential to create these compositions.

'The isotopic composition of the hydrogen and nitrogen trapped in the globules indicates they could have formed at the very outer reaches of the very early solar system or even in the 'molecular cloud' that the solar system formed from,' adds Caroline.

Vital for life

'These carbon-rich globules are abundant in the elements carbon, hydrogen, nitrogen and oxygen - all vital for life,' says Caroline. 'It is very possible materials such as these globules could have played an important role in providing the 'chemical building blocks' for life to start on the early Earth or even other planets and moons within our own solar system, like Mars.'

Uncontaminated

The Tagish Lake is a very unusual meteorite. Meteorites similar to Tagish Lake (known as the CI and CM carbonaceous chondrites or stony meteorites) make up only one per cent of known meteorites. It fell to Earth into a frozen lake in Canada in January 2000, and luckily, was picked up very soon after it fell, helping to keep any contamination from earth to a minimum.

'With all meteorite studies it is important to know that the material you are studying comes from the meteorite and not from contamination that the meteorite may have picked up whilst it has been on the Earth,' says Caroline. 'This is a particular problem when studying carbon-rich material in meteorites but fortunately the Tagish Lake meteorite was picked up very quickly.'

Future research on the Tagish Lake meteorite will undoubtedly reveal more secrets about the start of our solar system.

This research is reported in the journal Science .

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