NuSTAR

NuSTAR is a telescope launched into space by NASA in 2012. It is the eleventh satellite in the "Small Explorer" program. Telescopes in space can see much better than on Earth, because the telescopes on Earth need to look through the atmosphere. 
NuSTAR measures high-energy X-rays, which have a much higher frequency than visible light. It uses special optical devices to do this, so it works differently from a normal telescope. This type of telescope is called a Wolter telescope.
NuSTAR is searching for black holes. It is also looking at supernovae to help understand how the chemical elements are created. One of the first discoveries made by NuSTAR, along with another space telescope called XMM-Newton, was to measure the spin rate of a supermassive black hole for the first time.