Recently ESA published the results of a proof-of-concept study into monitoring marine litter using existing satellites, with promising results for the Mediterranean study area. For the study, six years of historical data from the Sentinel-2 satellite multispectral imaging cameras were used, involving 300,000 images with a resolution of 10 meters. The focus was on litter windrows as common collections of litter like plastic, wood and other types of marine debris that float on the surface, forming clearly visible lines that can be meters wide and many times as long.
This is a companion discussion topic for the original entry at https://hackaday.com/2024/06/19/mapping-litter-in-the-oceans-from-space-with-existing-satellites/