On Mars, dust and clouds are primary elements for studying the interactions of solar radiation with atmosphere and the surface. Depending on the opacity, particle size and refractive index, aerosol can provide positive or negative radiative feedbacks into the dynamical processes. For instance, the dust particles can act as ice nuclei for cloud formation, that in turns affects the vertical distribution of dust by cloud scavenging. To address these observations, the Radiation and Dust Sensor (RDS)  is part of the Mars Environmental Dynamics Analyzer (MEDA) payload onboard of the Mars 2020 rover Perseverance . RDS instrument compromises two sets of 8 photodiodes (RDS-DP) and a camera (RDS-SkyCam) . One set of photodiodes is pointed upward, with each one covering a different wavelength range between 190-1200 nm. The other set is pointed sideways, 20 degrees above the horizon, and they are spaced 45 degrees apart in azimuth to sample all directions at a single wavelength. The analysis of these observations with radiative transfer simulations will allow us to: i) determine the number density, size distribution and refractive index of dust particles; ii) detect and characterize clouds during twilight; and iii) detect dust lifting events near the surface such as dust-devils.
In this work we will present the first 100 sols observations made by RDS, as well as the optical properties and vertical distribution of dust and clouds estimated using radiative transfer modelling. These results will be compared with the observations made by other MEDA sensors.
References:  Apéstigue et al., (2015) EPSC, Nantes (France).  Rodriguez-Manfredi et al., special Mars2020 issue on SSR.  Lemmon et al., (2019) LPSC.