20-EPN-027: Characterisation of the response of an Optical Particle Counter in a simulated Martian environment
Visit by Giuseppe Mongelluzzo and Gabriele Franzese, INAF (Italy), to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 05-09 September 2022
Report summary: The characterisation of dust is paramount in the understanding of Martian climatology. Dust significantly influences Mars global climate, interacting with the incoming solar radiation, altering the atmospheric temperature budget. Local and global dust storms can cover the planet for weeks, influencing the correct functioning of scientific instruments on the surface (The Rover “Opportunity” is the most famous example). The dynamics of dust lifting is strictly related to the wind velocity field, so its characterisation would provide important information on the characteristics of Martian winds.
The proposing team has developed an Optical Particle Counter (OPC) aimed at providing direct measurements of grain concentration and size distribution on Mars, which would be the first ever accomplished outside of Earth. The instrument is able to detect dust grains in the 0.4-20 μm diameter range. Both the breadboard and the flight model versions of the instrument have been tested in Martian environment, showing good performances.
The trip to the Planetary Environment Facilities at the University of Aarhus has allowed the verification that the instrument is correctly able to sample dust grains in its upper sensible range (up to 20 µm in grain diameter) also in presence of winds up to 20 m/s. A sandbed with embedded dust has also been created inside the Martian wind tunnel, allowing the simulation of natural saltation conditions. The instrument has been able to retrieve dust grains in all simulated conditions, both for monodispersed calibrated dust samples and for polydisperse samples.
Read the full scientific report, with kind permission from Giuseppe Mongelluzzo.