ExoMars-2022 Mission ODS Instrument: Modeling and Ground Field Measurements

The paper presents the results of modeling and ground-based field measurements of the ODS (Optical Depth Sensor) instrument, designed to study aerosol in the Martian atmosphere through daily measurements of illumination on the planet’s surface. The device was part of the meteo suite located on the landing platform of the ExoMars-2022 mission. The article presents the structure of the instrument, its optical design and the spectral characteristics of two channels. The main elements of the model for calculating the radiation flux measured by the instrument are described depending on the structure of the atmosphere, the aerosol suspended in it, and the daily motion of the Sun. The calculations were carried out in the approximation of a pseudospherical atmosphere, taking into account the multiple scattering of radiation. Using the created model adapted for the Earth’s atmosphere, the ODS signal was simulated for two series of ground-based field measurements at different latitudes. The measured daily dependences in comparison with the simulation results make it possible to determine the optical depth with an accuracy of 0.1.