Ultraviolet scattering polarization from space particles entering Earth’s atmosphere

Abstract

Space material from leftovers of comets and asteroids is daily entering the Earth’s atmosphere. Traditionally, this influx has been characterized from ground-based observations or through meteorite searches. However, cosmic dust and small meteoroids (below a grain size of 1 cm) are not easily detectable with the current facilities and there is scant information about them. In this work, we analyse the feasibility of characterizing the low-mass end of the dust size distribution using observations at ultraviolet wavelengths from space. For this purpose, we have computed the expected scattered ultraviolet radiation and polarization produced by space dust falling on Earth using the Monte Carlo code RADMC-3D. We have built a density model attending to the features and parameters obtained from measurements of meteorites, meteor showers, and cometary dust observations. We show that silicate grains will be easily distinguishable from carbonates and irons based on polarization measurements. Moreover, the polarization reversals produced in the resonance scattering regime can be used to study the details of the size distribution of small dust grains. We point out the dependence of the modelled polarization on the way of discretizing the particle size distribution.