Submitted to The Astrophysical Journal. Preprint typeset using LATEX style emulateapj v. 08/22/09 THE NUCLEAR SPECTROSCOPIC TELESCOPE ARRAY (NUSTAR) HIGH ENERGY X-RAY MISSION

The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 13 June 2012, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates in the band from 3 – 79 keV, extending the sensitivity of focusing far beyond the ∼10 keV high-energy cutoff achieved by all pre-vious X-ray satellites. The inherently low-background associated with concentrating the X-ray light enables NuSTAR to probe the hard X-ray sky with a more than one-hundred-fold improvement in sensitivity over the collimated or coded-mask instruments that have operated in this bandpass. Using its unprecedented combination of sensitivity, spatial and spectral resolution, NuSTAR will pursue fiv