From a grant report submitted by Nicola Allen, ETH Zurich
Interplanetary dust particles (IDPs) are among the most primitive materials available for study, preserving organic matter and noble gases implanted during their journey through the Solar System. Their chemical and isotopic signatures can be modified during atmospheric entry, and understanding these effects is essential for reconstructing their origins and alteration histories.
We used the Meteoritical Society research grant funds to support a research visit to Carnegie Science, Washington DC, to undertake Raman spectroscopy and NanoSIMS analyses of one individual IDP and several fragments from one cluster IDP. Other fragments from these IDPs had previously been analysed for their noble gases at ETH Zurich, and their peak atmospheric entry temperatures were determined using calibrated ⁴He release curves. At Carnegie, Raman spectroscopy was used to determine the structural order of their carbonaceous material, and NanoSIMS provided isotopic maps of C, H and N to identify primitive organic signatures such as D‑rich and ¹⁵N‑rich hotspots. These measurements provide a combined dataset linking noble gas thermometry with nanoscale organic features in IDPs.
The Raman and NanoSIMS analyses show that the two particles differ in their organic and carbonaceous characteristics. The cluster IDP preserves very primitive carbon and diverse isotopic signatures, indicating minimal alteration. The individual IDP shows more homogeneous C, H and N isotopic, though structurally primitive carbon is still present. The combination of these measurements illustrate how organic matter in IDPs responds to heating and irradiation, providing broader insight into their alteration histories. Our findings demonstrate that calibrated ⁴He release curves can be used to estimate peak atmospheric entry temperatures in IDPs, and that combining these data with Raman and NanoSIMS analyses provides new insight into their origins and alteration histories.