NASA's NuSTAR mission will give sharper-than-ever views of the high-energy universe. But corralling X-rays is like herding cats. These wily photons have enough energy to penetrate through our skin and muscles as if they weren't even there, and bringing them to a focus is no easy task.

Principal Investigator Fiona Harrison (Caltech) tells Sky & Telescope how NuSTAR goes about capturing X-rays.