Diffraction limit for visible light would imply a rather huge aperture to be able to resolve 1cm on the ground from a low orbit. One that would stretch credulit

Diffraction limit for visible light would imply a rather huge aperture to be able to resolve 1cm on the ground from a low orbit. One that would stretch credulity. I would guess 5cm is achievable. Commercial applications are limited to 40ish cm. When I worked in aerial surveys we were working with an 8cm ground resolution, this was a good trade off point for wide field of view, motion blur, exposure, resolution and camera cost. So you can do a lot better for much cheaper with a plane (drones included). Plus you can fly under clouds and it is easy to change where you want images.