Laboratory light scattering from regolith surface and simulation of data by Hapke model

摘要

The small atmosphereless objects of our solar system, such as asteroids and the moon, are covered by layer of dust particles known as regolith, formed by meteoritic impact. The light scattering studies of such dust layer by laboratory experiment and numerical simulation are two important tools to investigate their physical properties. In the present work, the light scattered from a layer of dust particles, containing 0.3 mu m Al2O3 at wavelength 632.8 nm, is analysed. This work has been performed by using a light scattering instrument 'ellipsometer', at the Department of Physics, Assam University, Silchar, India. Through this experiment, we generated in laboratory the photometric and polarimetric phase curves of light scattered from such a layer. In order to numerically simulate this data, we used Hapke's model combined with Mie's single particle scattering properties. The perpendicular and parallel components of single particle albedo and the phase function were derived from Mie theory. By using Hapke's model combined with Mie theory, the physical properties of the dust grain such as grain size, optical constant (n,k) and wavelength can be studied through this scheme. In the literature, till today no theoretical model to represent polarisation caused due to scattering from rough surface is available, which can successfully explain the scattering process. So the main objective of this work is to develop a model which can theoretically estimate polarisation as caused due to scattering from rough surface and also to validate our model with the laboratory data generated in the present work. (C) 2016 Elsevier Ltd. All rights reserved.