Segmented mirrors sag under their own weight. Their optical shape must be controlled by computer-driven thrusters under the mirrors in what is called
A) an achromatic lens.
B) active optics.
C) a Schmidt-Cassegrain design.
D) a Newtonian design.
E) interferometry.

Question

Quizplus · Accepted Answer

Segmented mirrors need active optics because they have a tendency to sag under their own weight, which can affect their optical shape. Computer-controlled thrusters are used to adjust and maintain the correct shape of the mirror segments. Segmented mirrors sag under their own weight, and their shape must be controlled by computer-driven thrusters located under the mirrors. This technique is called active optics.

Segmented Mirrors Sag Under Their Own Weight