Robert A. Pritzker Assistant Curator of Meteoritics and Polar Studies Philipp Heck and co-authors from the Max-Planck-Institute for Chemistry in Germany had their paper on the first isotopic analysis of sulfur-rich comet dust published in the April issue of the journal Meteoritics & Planetary Science. The dust was captured during a flyby of Comet Wild 2 by NASA’s Stardust Mission and returned to Earth. Philipp used an ion microprobe at the Max-Planck-Institute for Chemistry in Germany to analyze the sulfur isotopic composition of 24 comet dust particles. His study finds that most of this comet dust formed in our solar system. There is only one grain that shows a chemical fingerprint that could indicate that it contains a real stardust sulfide grain, which formed in a supernova explosion outside of our solar system. Philipp’s findings contrast the view that comets are largely composed of stardust and also show that in this aspect comets are similar to primitive meteorites. The comet-equals-stardust view had to be abandoned following the initial analyses after the landing of the Stardust spacecraft showed that stardust in Stardust samples is very rare! Philipp's new study confirms this new view, and his paper can be accessed online here.