Aidan Ross

Centre for Planetary Sciences	Meteoritics and Cosmic Mineralogy
Earth Sciences Department	Mineralogy Department
University College London	Natural History Museum
Gower Street, London	Cromwell Road, London
WC1E 6BT	SW7 5BD

Tel: +44 (0)207 679 2577
Email: firstname DOT lastname AT ucl.ac.uk

About Me | Research | Publications | Other Interests

Research

For my PhD I am studying ureilite meteorites. Ureilites are the second most common group of achondrites and are thought to represent the mantle of a single asteroid ureilite parent body (UPB). I am studying the petrology, mineralogy and geochemistry of ureilites using various techniques, in order to draw conclusions about the formation and evolution of the UPB.

Ureilites can be separated into two groups: unbrecciated samples, which are believe to represent the interior of the UPB, and brecciated samples, which contain exotic components such as feldspathic clasts (possibly evidence for the "missing basalts" from the UPB), exogenic chondritic fragments and highly unusual Si-bearing metals. Some brecciated ureilites are regolith samples and can give insights into asteroidal surface processes. The origin of metals in brecciated ureilites has not been conclusively determined. Metal also occurs in some unbrecciated samples. I am performing EPMA and LA-ICP-MS to further understand both kinds of metal sample, in conjunction with my colleagues at JSC. Analyses of silicate minerals in ureilites give information about the history and evolution of the UPB asteroid. Ureilites are some of the most carbon-rich meteorites known and often contain micro-diamonds. I am conducting Raman spectroscopy and carbon isotope analyses to understand the method of diamond formation and the origin of carbon in ureilites.

The link between asteroids and meteorites is currently a highly relevant aerospace topic, with the arrival of the NASA Dawn mission to the asteroid Vesta scheduled for 2011 and the recent return of samples from the asteroid Itokawa by the Japanese Hayabusa mission. I am studying the meteorite Almahata Sitta, which was the first object to be tracked in space (as asteroid 2008 TC3) then recovered as a meteorite. Almahata Sitta was classified as an anomalous brecciated ureilite, providing unique samples for comparison with existing ureilites. This sample has gained both media attention and recognition in the scientific community with dedicated sessions at multiple conferences including the Lunar and Planetary Science Conference and Meteoritical Society Conference in 2010.

By examining multiple pieces of Almahata Sitta and other ureilites I can draw conclusions about the heterogeneity of the UPB asteroid and 2008 TC3, which was found to be a rubble-pile asteroid. Estimating the compositional variability within a single asteroid is important for future asteroid sample return missions as well as for remote sensing missions such as Dawn. Furthermore, clasts of other meteorite types have been found in Almahata Sitta, similar to those I have found in other ureilites, indicating a high degree of mixing in the asteroid belt. These observations must be taken into account when analysing asteroidal surfaces by remote sensing, as changes in chemistry may be due to addition of foreign meteorite types and not indigenous to the asteroid itself. Hence sample return from asteroids may produce more meaningful results, with the caveat that non-indigenous material may also be recovered from the surface.