Our solar system may have been created in a huge mixing process much bigger than previously imagined, according to research published today.
New analysis suggests a gigantic swirling disk of dust and gas that formed four and a half billion years ago later became our planets, asteroids and comets. The huge dust cloud was billions of kilometres across.
The findings, published in the journal Science, come from material collected by NASA's Stardust spacecraft from a comet called Wild 2. Because comets are probably among the oldest large objects in the solar system, researchers believe the dust can provide insights into how Earth and other planets were formed.
Scientists from Imperial College London and the Natural History Museum have been given a rare opportunity to analyse the comet dust. 'This is the first time scientists can work in the laboratory to study material undoubtedly from a comet, as it was taken directly from source,' said Anton Kearsley, X-ray Microanalyst at the Museum. 'The mission to secure material from the comet was remarkable. It flew further than any other return mission, 4.6 billion kilometres, meeting the comet between the orbit of Mars and the main asteroid belt, and then safely delivered samples to Earth.'
Gigantic mixing before the planets formed
The team found the comet dust is made up of many different mineral compositions
rather than a single dominant one. This implies the dust was formed in many different environments before coming together to make the comet, indicating a great deal of mixing in the early solar system prior to the formation of planets.
Particularly significant was the discovery of calcium- and aluminium-rich inclusions, which are among the oldest solids
in the solar system. They are thought to have formed close to the young sun. This suggests components of the comet came from all over the early solar system. Some dust was formed close to the sun, while other material came from the asteroid belt between Mars and Jupiter. Since Wild 2 formed in the outer solar system, this means some of its composite material has travelled huge distances.
Although scientists now know much more about Wild 2 and its composition, the research raises new questions. Is this a typical comet and have other comets had very different histories? Research on comet dust has only just begun and the examination of these samples is truly the new frontier of planetary science.
Further research at the Museum
The Museum and partner organisations have been awarded a €2.6 million grant
by the European Commission to bring together a multi-disciplinary team of European scientists for the first time. The project, called Origins,
seeks to better understand the origins of our planetary system and those beyond it.
Sara Russell, Head of Meteoritics and Cosmic Mineralogy at the Museum, is spearheading the effort, which will start next month.
'The quest for knowledge about the origins of planets and stars has always been a central preoccupation of humankind,' said Sara. 'This project goes someway to satisfying this quest and will enrich the cosmochemical research community within Europe.'