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2 Posts tagged with the meteorite tag
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Wild Stardust

Posted by John Jackson Dec 23, 2011

Samples returned from comet 81P/Wild 2 by the Stardust mission provided an unequalled opportunity to compare previously available extraterrestrial samples against those from a known comet. Iron sulphides are a major constituent of cometary grains commonly identified within cometary interplanetary dust particles (IDPs) and Wild 2 samples.  NHM scientists Sara Russell and Anton Kearsley, and Scientific Associate Phil Bland, are key collaborators on a new examination of this unique material.

 

Chemical analyses show that Wild 2 sulphides are fundamentally different from those in IDPs. However, as Wild 2 dust was collected via impact into capture media at approximately 6.1 km s-1, it is unclear whether this is due to original variations in these materials or is due to heating and alteration during collection. The results obtained are consistent with estimated peak pressures and temperatures experienced (approximately 85 GPa, approximately 2600 K) and some may be used to predict original chemistry and estimate mineralogy - the work continues....


Wozniakiewicz P J, Ishii H A, KEARSLEY A T, Burchell M J, BLAND P A, Bradley J P, Dai Z R,   Teslich N, Collins G S, Cole M J & RUSSELL S S 2011. Investigation of iron sulfide impact crater residues: A combined analysis by scanning and transmission electron microscopy. Meteoritics and Planetary Science 46: 1007-1024.

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Meteorites from the Moon

Posted by John Jackson Jan 4, 2011

Samples from the Moon come either from lunar landing missions - the US Apollo or Soviet Luna sample return missions - or from lunar meteorites.  The Moon's craters show a history of impacts by smaller space bodies that, when they have collided with the Moon, have flung Moon rock into space. 

Some of this material has eventually fallen to the surface of the Earth as lunar meteorites, although these have only been recognised as such since 1982 when some unusual meteorites were compared with rocks retrieved by lunar missions. Over 130 meteorites have now been recognised as of lunar origin.

Scientists from the Museum's meteorite research group, Professor Sara Russell and Anton Kearsley, have collaborated with partners from London University's UCL and Birkbeck College to study four lunar regolith breccia meteorites that provide sampling of the lunar surface from regions of the Moon that were not visited by the US and Soviet missions. They used equipment in the Museum's analytical laboratories to show that these meteorites represent impact melts formed from rocks of compositions distinct from those sampled by the Apollo missions - there is considerable variability in rock types across the surface of the moon.

JOY K H, Crawford I A, RUSSELL S S & KEARSLEY A T (2010) Lunar meteorite regolith breccias: An in situ study of impact melt composition using LA-ICP-MS with implications for the composition of the lunar crust. Meteoritics and Planetary Science 45: 917-946. DOI: 10.1111/j.1945-5100.2010.01067.