This is an amazing idea for sci-fi! Spread the masses out over orbit, measure net gravity on those (by orbit deviations?), and you should be able to detect cha

This is an amazing idea for sci-fi! Spread the masses out over orbit, measure net gravity on those (by orbit deviations?), and you should be able to detect changes in gravity from distant objects. With enough spread maaaaybe you could do something with parallax to detect distance too. Imagine a system like this in 'the expanse' to detect the stealth asteroids hurled towards earth. Or, in general, to detect massive ships that are 'on the float'.