Mirror, Mirror on the Wall

Another reason why a telescope like the Chandra X-ray Observatory is so remarkably successful is that X-ray astronomy is very technically challenging. One of the biggest problems is that X-rays that strike a 'regular' mirror head on will just be absorbed. In order to focus X-rays onto a detector, the mirrors have to be shaped like barrels so that the X-rays strike them at grazing angles, just like pebbles skipping across a pond.

More Information: Telescope System