OBSERVATIONS OF HARD X-RAY EMISSION FROM ROTATION-POWERED PULSARS ARE CRUCIAL FOR UNDERSTANDING THE PHYSICS OF PULSAR MAGNETOSPHERES. HOWEVER ONLY A HANDFUL OF BRIGHTEST PULSARS HAVE BEEN OBSERVED AT THESE ENERGIES AND MOST OF THEM HAVE NOT BEEN INVESTIGATED IN DETAIL. TO PROBE THE MAGNETOSPHERE OF THE YOUNG ENERGETIC PSR J1617-5055 WHOSE PROPERTIES ARE DRASTICALLY DIFFERENT FROM THOSE OF THE BEST-INVESTIGATED CRAB PULSAR WE PROPOSE A NUSTAR OBSERVATION FOR PHASE-RESOLVED SPECTROSCOPY AND ENERGYRESOLVED TIMING OF PULSAR RADIATION. BEING BRIGHT IN HARD X-RAYS THIS PULSAR HAS A VERY UNDERLUMINOUS PULSAR WIND NEBULA WHICH GREATLY FACILITATES NUSTAR DATA ANALYSIS.