Another thing I'm wondering: the drones can probably carry only a small (light) camera, whereas a satellite can carry much more and thus also a much better camera. Wouldn't a satellite+camera be a better option?
For a given aperture there's a limit to the angular resolution you can get which means you can only see objects above a certain size from orbit. The highest resolution we had in 2013 had a resolution of ~.3m/pixel. That's too large for anything beyond rough mapping for things like landing or a vague plan for driving.
TL;DR a decent camera at <1km is hard to beat from >100km no matter how good the satellite camera is.
