I wonder what "earth observation" opportunities there would be with such megaconstellations, from simply having a camera with a telephoto lens pointed down to a giant, sky-spanning Synthetic Aperture Radar utilizing multiple satellites.
Probably few. The US has excellent observers and comms sats by the dozens are not very big. It's true you can get some photos but the kind you're thinking of, where you can track vehicles in a meaningful way or something, has to be done by something closer to the hubble telescope (pointed backwards).
Even if it would just deliver 1 or even just 10 meter resolution, I would imagine the high revisit frequency would make it commercially valuable, and potentially also provide some value to military/intelligence groups because it would make it harder to hide activity through careful timing and the data would come with fewer secrecy requirements.
And I have no clue what is doable with SAR, but I'd imagine multiple satellites following each other would enable some interesting features, as it essentially gives you a giant antenna.
> has to be done by something closer to the hubble telescope (pointed backwards).
state of the art is about 2x diameter, with adaptive optics methodologies that avoid needing to polish a giga-mirror over several years
The observation cadence could be game-changing. Instead of once-, twice- daily revisit times, in principle you could contemplate continuous observation, of large parts of the Earth, from LEO, with enough downstream bandwidth to make interesting use of all that data.
Ive seen a video around 2005 about USA spy satellites/drones where they kind of disclosured what was possible at this time. Having a very wide area with realtime object/person tracking and multiple terrabytes of data every minute while beeing able to go back in time with all this features.
This all was like 20 years go. 20. 20!!
Than I see my upper consumer grade canon camera, a r6mkII with 70-200mm lens (mk1, 20 years old) that is able to make a photo of some dog in high speed motion, with a 1/800 shutter with 200mm while its dawn and you are still perfectly able to zoom into the photo and see and identify a midget [1]
It’s a 450km orbit. Cameras are good, but you’d need quite a bit of mass per satellite to identify anything of interest that isn’t already covered by other satellites. At a certain point photography becomes more a matter of optics (using lens to collect light) than anything else.
Anything like that would explain the secrecy...