NuSTAR continues to do well. Right now we're pointing at a neutron star called Hercules X-1. Neutron stars have masses somewhat larger than our Sun, but are as compact as San Francisco. A teaspoon weighs as much as all the humans on Earth. These objects also have very intense magnetic fields. When they are in a binary system with a "normal" star matter can be transferred from the star to the neutron star. The huge magnetic fields create distortions in the spectrum (or rainbow) of X-rays that result, and NuSTAR will study this distorted spectrum to understand the physics taking place in these systems.
In other news - want to catch up in person? We're hosting a google+ event to roll out the KQED (Bay Area public television) show on black holes, highlighting NuSTAR.
Add KQED Science to your circle and you'll find the event.