Probing the diversity of cometary organics with Antarctic micrometeorites

The micrometeorite (MM) population in near Earth orbit (~1 au) is estimated to be dominated by cometary dust. Collecting MMs at the Earth's surface is the first step toward the identification of cometary particles. Among the diversity of particles in the Concordia MM collection (Dome C, Antarctica), fine-grained particles and ultra-carbonaceous MMs have high carbon abundances, up to 60 wt.%, that is mostly macromolecular (‘refractory’) organics. These MMs are proposed to be of cometary origin and enable us to study in detail the nature of organics from primitive Solar System objects. This presentation will highlight the insights that can be gained from measurements of the H, C, and N isotopic compositions of the organics in MMs, and how they can be used to help draw links between interplanetary dust and the volatile reservoirs of the Solar System.

Julien Rojas-Arispe is a cosmochemist who specializes in the isotopic compositions of organic matter and the flux of interplanetary dust. Coming to EPL from his Ph.D. at the University of Paris-Saclay, he joined the Carnegie Institution for Science to gain insight into the furthest reaches of our Solar system through the isotopic analysis of ultra-carbonaceous Antarctic micrometeorites.