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RAS PN09/24 (NAM11): Primitive dust samples provide pre-solar time-capsules

Last Updated on Thursday, 23 April 2009 13:08
Published on Sunday, 19 April 2009 00:00
dust_particle.jpgAn international team of scientists has found some of the most primitive matter containing abundant interstellar material analysed to date amongst dust particles collected from the upper atmosphere by NASA aircraft.  The samples were gathered in April 2003 during the Earth's passage through the dust stream left behind by comet 26P/Grigg-Skjellerup.  Dr Henner Busemann of the University of Manchester will present the results at the European Week of Astronomy and Space Science at the University of Hertfordshire on Tuesday 21st April.

“We found an extraordinary wealth of primitive chemical "fingerprints", including abundant pre-solar grains, true stardust that has formed around other earlier stars, some during supernova explosions, associated with extremely pristine organic matter that must pre-date the formation of our planets,” said Dr Busemann.

The interplanetary dust particles, which are only a few thousands of a millimetre in diameter, were analysed by an international collaboration from the UK, the US and Germany. Two grains appear to have percentage levels of material thought to match the nebula from which the Solar System formed.  One dust particle contained four pre-solar silicate grains with an unusual chemical composition that matches predictions for silicates formed from cooling gas following a supernova explosion. One of these grains, a fragment of olivine, was found next to a hollow, globule of carbon, most likely of interstellar origin.  Organic coatings are suspected to be the time-capsules that protected and secured the survival of some of these fragile stellar silicate grains in the radiating space environment.

"These tiny grains combine all the most primitive features, found to date only separately in various meteorites, samples from the Stardust mission and interplanetary dust particles. The particular collection scenario allows us speculate that we truly have samples of a known source, comet Grigg-Skjellerup, in our hands,” said Dr Busemann.

The group compared their findings with Deep Impact observations of comet 9P/Tempel 1 and analyses of samples from comet 81P/Wild 2 collected by Stardust.  The comparison revealed surprising differences between the comets, which are all short-period comets with orbits constrained by Jupiter’s gravitational field.  Comet 81P/Wild 2 was found to have incorporated much higher levels of material formed in the inner Solar System, however all the comets contained materials such as carbonates that commonly indicate the presence of water.


The primitive matter, containing unaltered samples of the building blocks of our Solar System, gives insights into the turbulent processes leading to the formation of our Solar System and also the fate of comets orbiting since their formation at the outer edges of our planetary system. While the planets in the inner solar system, such as Earth or Mars, once experienced harsh conditions and have changed substantially over the past 4.5 billion years, comets are believed to store the original material of the early Solar System, acting as ‘supersized refrigerators’. 

“We still have much to learn from samples of primitive matter containing large amounts of interstellar grains. Aircraft offer a less costly way to collect cometary dust, albeit of unknown origin. Predictions and timed collection campaigns in the future offer an increased likelihood to analyse material from known comets without actually going there," added Dr Busemann.

NOTES FOR EDITORS

THE EUROPEAN WEEK OF ASTRONOMY AND SPACE SCIENCE
More than 1000 astronomers and space scientists will gather at the University of Hertfordshire for the European Week of Astronomy and Space Science (EWASS), incorporating the 2009 Royal Astronomical Society National Astronomy Meeting (RAS NAM 2009) and the European Astronomical Society Joint Meeting (JENAM 2009). The meeting runs from 20th to 23rd April 2009.
 
EWASS is held in conjunction with the UK Solar Physics (UKSP) and Magnetosphere Ionosphere and Solar-Terrestrial Physics (MIST) meetings. The conference includes scientific sessions organised by the European Organisation for Astronomical Research in the Southern Hemisphere (ESO) and the European Space Agency (ESA).

EWASS is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and the University of Hertfordshire, Hatfield.

THE ROYAL ASTRONOMICAL SOCIETY
The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

Contacts
Dr Henner Busemann
School of Earth, Atmospheric and Environmental Sciences
University of Manchester
Williamson Building
Oxford Road
Manchester
M13 9PL
Tel: +44-161-2750769
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

Images
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Interplanetary dust particles showing pre-solar silicate grains and organic matter of interstellar origin. Credit: H Busemann.

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Interplanetary dust particles showing pre-solar silicate grains and organic matter of interstellar origin. Credit: H Busemann.