Q&A: Chandra Mission

Q:
What is the reflective power of the mirrors used in Chandra telescope?

A:
The reflectivity varies with the energy of the X-rays. It is near 100% for the lowest energy X-rays (0.1 kilovolt), about 80% up to 2 kilovolts, and slowly declining down to 10% at the highest energy of 10 kilovolts.