Using synchrotron transmission X-ray Diffraction (XRD) and X-ray Absorption Spectroscopy (XAS) techniques we have previously shown the presence of magnetite in terminal grains from Stardust cometary tracks, suggesting that the parent body of comet Wild2 underwent hydrous alteration.

The presence of magnetite in Wild2 is similar to its occurrence within the matrices of many carbonaceous chondrites. It is assumed to be the result of the hydrous alteration of co-existing ferromagnesian minerals, which are also present in the Wild2 terminal grains analysed here and by [1] and [2]. There is a variety of growing evidence for both low temperature hydrous processes such as magnetite formation, and also high temperature processing and the formation of chondrules in the Wild2 solid precursors.

In order to test the consensus that Wild2 is similar to carbonaceous chondrites, and to identify the most similar types; we are performing similar XRD and XAS analyses on powders prepared from CV3 and CR2 carbonaceous chondrites, which have been fired into aerogel at 6 km s-1, at the University of Kent.

[1] Brownlee D.: The Stardust Mission: Analyzing Samples from the Edge of the Solar System, A. Rev. EPS 42, 179–205, 2014. [2] Zolensky M. et al.: Mineralogy and Petrology of Comet 81P/Wild2 Nucleus Samples, Science, 314, pp. 1735-1739, 2006.