Analisi di regioni con basso albedo sulla superficie di Marte

Several active low albedo features, including Slope Streaks (SSs), Recurring Slope Lineaes (RSLs) and dark dune features, are observed on present-day dry and cold Martian surface. However, the conditions of Martian surface are dry and cold, which seem to be unfavorable for the presence of liquid water. Both dry and wet models are proposed to explain their formation, but the lack of strong evidences makes them be debated. In this thesis, we report a new seasonal low albedo feature observed on the edge of South Polar Layered Deposits (SPLDs), named as Low Albedo Streak (LAS). In order to understand the physical processes of their formation, we perform analyses about their morphology, surface topography, mineralogy and thermal condition based on multiple datasets. These analyses indicate that percolating of supercooling liquid water may currently occur on Mars. In addition, several new characteristics of Dark Dune Spots (DDSs) are observed in two craters, including the repeated changes of diameter of DDSs in a short period, the distinct bright cores forming within DDSs at the end of DDSs’ evolution, and the bright deposits observed with the disappearance of DDSs. The combined analyses between these characteristics and surface thermal conditions indicate that water may play a key role in the evolution of DDSs. Finally, a liquid jet model is established to explain the formation of SSs. we found that the liquid jet-based model seems to be able to explain more observed characteristics of SSs simultaneously compared to the dry- and wet-based models proposed before.