> > They could aim the telescope not by moving the dish, but by moving the focal point/receiver.
> As the Moon is tidally locked - that long stare limitation remains.
See the point now? Passive radio observation doesn't change the fact that the Moon orbits the Earth - and has an even longer delay between revisits to the same patch of sky.
Yeah it's not going to be able to point for days at a single target but that will be helped by the relative silence of where it is.
> Arecibo was distance limited by the Earth's rotation speed, since radar returns had to make it back before the target shifted out of the telescopes steerability window
You were talking about active radar ranging a lot though which is not at all what these are meant for. It's like complaining a car can't tow a trailer, it's technically true but it's orthogonal to it's intended purpose.
> ...it's technically true but it's orthogonal to it's intended purpose.
Well that is the more verbose and less helpful way of saying the same thing: can't do long stare for the same reason this recognizable thing couldn't - rotation. Sticking with your car analogy: Upon hearing somebody else answer the question of "Can this car tow a trailer?", you swing in on a chandelier and declare "Actually it can, if the trailer is imaginary!"
> > They could aim the telescope not by moving the dish, but by moving the focal point/receiver.
> As the Moon is tidally locked - that long stare limitation remains.
See the point now? Passive radio observation doesn't change the fact that the Moon orbits the Earth - and has an even longer delay between revisits to the same patch of sky.