NuSTAR is a satellite-based observatory sensitive in the hard X-ray band covering the energy range of 5-80 keV. It was developed and built under the auspices of NASA's Explorer program, led by Caltech (PI Fiona Harrison), with involvement of many other institutions including Stanford, JPL, Columbia University, UC Berkeley, NASA-Goddard, McGill, Danish Space Research Institute, MIT, and Yale. It features several new technologies, including focusing optics with multi-layer coatings (necessary to reflect hard X-rays), a sensitive, pixilated CdZnTe detector camera to enable imaging, and an extendable optical mast connecting the two and allowing the required focal length of 10 meters. Those technologies enable an observatory at least 100 times more sensitive than previous facilities.
The mission was launched on June 13, 2012. The objects studied by NuSTAR will include black holes with a wide range of masses, to determine their distribution in the Universe; remnants of exploded stars, to study the process of formation of elements in our galaxy; and, working in tandem with the Fermi Gamma-ray Space Telescope, the nature of powerful, relativistic jets, which are also source of energetic gamma-rays.