Coffee talks
Friday 17/04/2026 @ 11:30, Sala riunioni quarto piano e on-line (meet.google.com/sue-bwvk-axf)
Graziella Caprarelli (Centre for Astrophysics, University of Southern Queensland, Australia; INAF-IRA, Bologna), "Mars: the unknown planet"
One of the primary objectives of the Mars Express mission (2003-ongoing), and a specific target for the radar sounder MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding), is to map the distribution of ice and water on Mars. In 2018 a team of scientists (Orosei et al., 2018 https://doi.org/10.1126/science.aar7268) reported on the detection of bright radar reflections from the base of the South Polar Layered Deposits (SPLD), suggesting the presence of a pool of liquid brines 20-30 km across. The work was followed by the analysis of hundreds of MARSIS data acquired over a region known as Ultimi Scopuli, where the SPLD is 1.5 km thick, confirming the initial findings and showing that the bright reflector was surrounded by at least three other high reflectivity areas, each approximately 10 km across (Lauro et al., 2021 https://doi.org/10.1038/s41550-020-1200-6). The most plausible interpretation of the data is that the base of the deposits is wet. This interpretation appears inconsistent with the current tenet of a hyperarid and frigid Mars, where water only exists as ice, or trapped within the molecular structure of minerals. Thus far, however, no alternative explanation for the origin of the bright reflections has proven plausible, leaving the liquid brine interpretation as the only viable one (Stillman et al., 2022 https://doi.org/10.1029/2022JE007398). I posit that the detection of MARSIS bright basal reflectors ought to be regarded as a “data-point” to constrain the thermal conditions and the climatic evolution of Mars, rather than the other way around. In this presentation I outline existing gaps in our knowledge and understanding of the formation and evolution of this fascinating planet, and explore a plausible planetary picture based on the presence of wet areas at the base of the polar caps of Mars that might reconcile the available geological and climatic evidence with MARSIS observations.