Yeah, once these things are moving, you don't need much resolution to see them - we're talking about objects several kilometers wide, at the very least. Easily visible on even the most primitive satellite imagery. The difficulties would be cloud cover and orbital inclination.

> I assume late 80s was recent enough for decent resolution space imagery?

Landsat (https://en.wikipedia.org/wiki/Landsat_program) was likely the best available imagery back then. In the 80's it looks like they had 60m resolution - I assume that would be big enough to see an iceberg?

I'm not an expert on icebergs but I have used enough satellite imagery to answer... Yes the 60m Landsat imagery would show large icebergs under its ground track.