Radar satellites
I have spent a fair amount of time going through Tomnod images, and there is a lot of clouds out there.
There are a large number of radar satellites out there, mostly operated by government bodies (DOD, NASA, Canada, etc.) but also a few private companies. These have resolutions good enough to spot some of this flotsam. They can be operated day and night, and can see through the clouds. Anyone hear any rumors of these being used over the search areas?