NEWS | Scattering

	Experimental Scattering Matrices of Martian Dust Aerosols with Narrow Particle-size Distributions We present experimental scattering matrices of the JSC Mars-1, MMS-2, and MGS-1 simulants at 488 and 640 nm. The analogs were processed so that narrow size distributions representative of Martian dust aerosols during different dust cycles were obtained. We find that the forward peak of the phase function depends on particle size as it becomes narrower with increasing size, whereas the side- and backscattering directions depend on both composition and size so that increasing size and decreasing absorption produce a flatter curve.
	Experimental Phase Function and Degree of Linear Polarization of Light Scattered by Hydrogenated Amorphous Carbon Circumstellar Dust Analogs Astronomical observations of the polarized intensity of scattered visible light have revealed the presence of dust envelopes around different types of evolved stars. These observations have helped determine the diameter and width of dust shells around stars with unprecedented accuracy. Simple geometric particle models are used in order to retrieve dust properties from these observations.
	Optical Constants of Martian Dust Analogs at UV–Visible–Near-infrared Wavelengths We present an advanced light-scattering model to retrieve the optical constants of three Martian dust analogs: Johnson Space Center regolith simulant, Enhanced Mojave Mars Simulant, and Mars Global Simulant. The samples are prepared to have narrow particle-size distributions within the geometric-optics domain. We carry out laboratory measurements to obtain the particle-size distributions, shapes, and diffuse reflectance spectra of the Martian analogs deposited on a surface.
	Experimental phase function and degree of linear polarization curve of olivine and spinel and the origin of the Barbarian polarization behaviour. We explore experimentally possible explanations of the polarization curves of the sunlight reflected by the Barbarian asteroids. Their peculiar polarization curves are characterized by a large-inversion angle, around 30 degrees, which could be related to the presence of FeO-bearing spinel embedded in Calcium–Aluminum inclusions. In order to test this hypothesis, we have measured the phase function and degree of linear polarization of six samples of Mg-rich olivine and spinel.
	Retrieving Dust Grain Sizes from Photopolarimetry We present the experimental phase function, degree of linear polarization (DLP), and linear depolarization (δL) curves of a set of forsterite samples representative of low-absorbing cosmic dust particles. The samples are prepared using state-of-the-art size-segregating techniques to obtain narrow size distributions spanning a broad range of the scattering size parameter domain.
	On the application of scattering matrix measurements to detection and identification of major types of airborne aerosol particles: Volcanic ash, desert dust and pollen Atmospheric aerosols play key roles in climate and have important impacts on human activities and health. Hence, much effort is directed towards developing methods of improved detection and discrimina- tion of different types of aerosols. Among these, light scattering-based detection of aerosol offers several advantages including applications in both in situ and remote sensing devices. In this work, new scat- tering matrix measurements for two samples of airborne desert dust collected in Spain and China are reported.
	ROADMAP: Role and impAct of Dust and clouds in the Martian AtmosPhere: from lab to space ROADMAP is an H2020-SPACE-2020 new project CoDuLab is involved in. The project's goal is to drastically enhance our knowledge of the Red Plant by focusing on the prominent role of dust and clouds in its atmosphere. By combining light scattering experiments and observations, ROADMAP will study the composition of the Martian atmosphere, contribute to a better understanding of the physical processes in occurring in there and improve the modelling of dust and water cycles in it.
	Experimental phase function and degree of linear polarization curves of millimeter-sized cosmic dust analogs We present laboratory measurements of the phase functions and degree of linear polarization(DLP) curves of a selection of millimeter-sized cosmic dust analog particles. The set includes particles with similar sizes but diverse internal structure(compact and porous) and absorbing properties. The measured phase functions are found to be in all cases very different from those of micron-sized particles. They show a monotonic decrease with increasing phase angle from the back- to the side-scattering region, reaching a minimum at large phase angles before a steep increase of the forward peak.
	Light scattering from volcanic-sand particles in deposited and aerosol form The light-scattering properties of volcanic sand collected in Iceland are studied here to characterize the sand particles and develop a reference for future remote-sensing observations. While such sand is common in Iceland, the smaller-size fraction can be readily transported by winds and found in the atmosphere at distant locations. The sand appears dark when deposited on a surface due to the high optical absorption of the material. Therefore, atmospheric regions containing such particles during a dust storm may absorb sunlight considerably, causing redistribution of solar energy.
	Experimental phase function and degree of linear polarization of cometary dust analogues We present experimental phase function and degree of linear polarization curves for seven samples of cometary dust analogues namely: ground pieces of Allende, DaG521, FRO95002, and FRO99040 meteorites, Mg-rich olivine and pyroxene, and a sample of organic tholins. The experimental curves have been obtained at the IAA Cosmic Dust Laboratory at a wavelength of 520 nm covering a phase angle range from 3◦ to 175◦. We also provide values of the backscattering enhancement for our cometary analogue samples.