IDENTIFICATION AND ANALYSIS OF INTERPLANETARY DUST PARTICLES FILTERED FROM ANTARCTIC AIR

Interplanetary dust particles (IDPs) are among the most fine-grained extraterrestrial objects available for study in the lab. Many are composed of primitive materials that have experienced very little alteration or processing since their formation early in Solar System history. Samples collected by filtering of air from the Clean Air Sector near South Pole Station in Antarctica [1] include a number of extraterrestrial and candidate IDPs. We will present results on analysis of several newly identified candidate grains that were first screened using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The candidate grains will be studied using electron energy loss spectroscopy (EELS) and EDS in the scanning transmission electron microscope (STEM) and using NanoSIMS for isotopic measurements, which provide further information about the sources of these grains. Several of the grains that we have identified on the filters are nominally Fe-free, Mg-silicates consistent with an extraterrestrial origin, while others are more similar to bulk chondritic compositions. A couple of these candidate IDPs are dominantly carbonaceous but with a few individual silicate grains and some elongate grains that could be enstatite “whiskers,” a feature associated with these primitive materials [2]. This is reminiscent of ultracarbonaceous micrometeorites, thought to be cometary in origin [3]. This combination of techniques provides a powerful way of learning more about these primitive materials and their origins within our Solar System, whether they are collected by sample-return missions or sorted from terrestrial materials after they have fallen to Earth.

[1] Taylor, S., et al. (2017) LPSC 2024.

[2] Bradley, J.P., et al. (1983) Nature, 301, 473.

[3] Duprat et al. (2010) Science 328, 742.