I'm not sure about its space applications, but synthetic aperture radar has improved shockingly (I don't use the term lightly) over the past couple decades.
Yes it has but "it ain't that good". There's a lot of RF noise up there, so they still use air-based platforms such as Raytheon ASTOR/Sentinel. They're cheaper as well, even if you need a couple of Tornados to follow it.
I'm not saying any more otherwise I'll probably get bagged and tagged.