Comment by ben_w

I doubt it's "real time" even now.

That said, my actual experience of processing earth observation satellite images was with scientific data, not spy sats, and in any case it was just over 20 years ago and may be out of date.

What I was working with, any given satellite image capture was a line rather than a rectangle, basically a rolling shutter effect but on a planetary scale and taking ~90 minutes: https://en.wikipedia.org/wiki/Push_broom_scanner