Iron oxides in comet 81P/Wild 2

DOI: 10.1111/j.1945-5100.2009.01005.x

Authors: John Bridges (University of Leicester) , Mark Burchell (University of Kent) , Hitesh Changela (University of Leicester) , Nick Foster (University of Kent) , Alan Creighton (University of Kent) , James Carpenter (University of Leicester) , Steve Gurman (University of Leicester) , Ian Franchi (Open University) , Henner Busemann (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Meteoritics & Planetary Science , VOL 45 (1) , PAGES 55 - 72

State: Published (Approved)
Published: February 2010

Abstract: We have used synchrotron Fe-XANES, XRS, microRaman, and SEM-TEM analyses of Stardust track 41 slice and track 121 terminal area slices to identify Fe oxide (magnetite-hematite and amorphous oxide), Fe-Ti oxide, and V-rich chromite (Fe-Cr-V-Ti-Mn oxide) grains ranging in size from 200 nm to ∼10 μm. They co-exist with relict FeNi metal. Both Fe-XANES and microRaman analyses suggest that the FeNi metal and magnetite (Fe2O3FeO) also contain some hematite (Fe2O3). The FeNi has been partially oxidized (probably during capture), but on the basis of our experimental work with a light-gas gun and microRaman analyses, we believe that some of the magnetite-hematite mixtures may have originated on Wild 2. The terminal samples from track 121 also contain traces of sulfide and Mg-rich silicate minerals. Our results show an unequilibrated mixture of reduced and oxidized Fe-bearing minerals in the Wild 2 samples in an analogous way to mineral assemblages seen in carbonaceous chondrites and interplanetary dust particles. The samples contain some evidence for terrestrial contamination, for example, occasional Zn-bearing grains and amorphous Fe oxide in track 121 for which evidence of a cometary origin is lacking.

Subject Areas: Physics


Instruments: I18-Microfocus Spectroscopy