Other great answers, but if those things weren’t an issue I think also you’d need one sensor for each mirror, and the sensor is bigger and heavier and more comp

Other great answers, but if those things weren’t an issue I think also you’d need one sensor for each mirror, and the sensor is bigger and heavier and more complex than a single mirror. Or you could just watch the same mirror for X times longer where X is the number of mirrors, but then you’d get 1/X as many observations.