The micrometeorite flux at Dome C (Antarctica), monitoring the accretion of extraterrestrial dust on Earth

1J.Rojas,2,1J.Duprat,1C.Engrand,3E.Dartois,1L.Delauche,1,3M.Godard,2M.Gounelle,4,5J.D.Carrillo-Sánchez,4,6P.Pokorný,7J.M.C.Plane
Earth and Planetary Science Letters 560, 116794 Link to Article [https://doi.org/10.1016/j.epsl.2021.116794]
1Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France
2IMPMC, CNRS-MNHN-Sorbonne Universités, UMR7590, 57 rue Cuvier, 75005 Paris, France
3ISMO, CNRS, Univ. Paris Saclay, Bât 520, 91405 Orsay, France
4Department of Physics, Catholic University of America, 620 Michigan Ave., N.E. Washington, DC 20064, USA
5ITM Physics Laboratory, NASA Goddard Space Flight Center, Code 675, 8800 Greenbelt Rd., Greenbelt, MD 20771, USA
6Astrophysics Science Division, NASA Goddard Space Flight Center, Code 667, 8800 Greenbelt Rd., Greenbelt, MD, USA
7School of Chemistry, Univ. of Leeds, Leeds LS2 9JT, UK
Copyright Elsevier

The annual flux of extraterrestrial material on Earth is largely dominated by sub-millimetre particles. The mass distribution and absolute value of this cosmic dust flux at the Earth’s surface is however still uncertain due to the difficulty in monitoring both the collection efficiency and the exposure parameter (i.e. the area-time product in m2.yr). In this paper, we present results from micrometeorite collections originating from the vicinity of the CONCORDIA Station located at Dome C (Antarctica), where we performed several independent melts of large volumes of ultra-clean snow. The regular precipitation rate and the exceptional cleanliness of the snow from central Antarctica allow a unique control on both the exposure parameter and the collection efficiency. A total of 1280 unmelted micrometeorites (uMMs) and 808 cosmic spherules (CSs) with diameters ranging from 30 to 350 μm were identified. Within that size range, we measured mass fluxes of 3.0 μg.m−2.yr−1 for uMMs and 5.6 μg.m−2.yr−1 for CSs. Extrapolated to the global flux of particles in the 12-700 μm diameter range, the mass flux of dust at Earth’s surface is tons.yr−1 ( and tons.yr−1 of uMMs and CSs, respectively). We indicate the statistical uncertainties expected for collections with exposure parameters in the range of 0.1 up to 105 m2.yr. In addition, we estimated the flux of altered and unaltered carbon carried by heated and un-heated particles at Earth’s surface. The mass distributions of CSs and uMMs larger than 100 μm are fairly well reproduced by the CABMOD-ZoDy model that includes melting and evaporation during atmospheric entry of the interplanetary dust flux. These numerical simulations suggest that most of the uMMs and CSs originate from Jupiter family comets and a minor part from the main asteroid belt. The total dust mass input before atmospheric entry is estimated at 15,000 tons.yr−1. The existing discrepancy between the flux data and the model for uMMs below 100 μm suggests that small fragile uMMs may evade present day collections, and/or that the amount of small interplanetary particles at 1 AU may be smaller than expected.

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