THE NUSTAR SATELLITE PROVIDES MAJOR IMPROVEMENTS OVER PREVIOUS HARD X-RAY (>10 KEV) SATELLITES IN TERMS OF SENSITIVITY AND ENERGY RESOLUTION ENABLING HIGH-QUALITY HARD X-RAY MEASUREMENTS OF ACCRETING BLACK HOLE SYSTEMS AT LOW LUMINOSITY. THIS IS THE FIRST TIME THAT MEASUREMENTS OF THE ENTIRE COMPTON REFLECTION COMPONENT FROM THE ACCRETION DISK WILL BE POSSIBLE AT LOW MASS ACCRETION RATES IN THE HARD STATE. AS THIS IS THE ONLY STATE WHERE STEADY JETS ARE DETECTED THIS PROVIDES A NEW WINDOW ON THE DISK/JET CONNECTION BY USING NUSTAR TO MEASURE THE SYSTEM GEOMETRY (AND ITS EVOLUTION) WHILE MEASURING THE STRENGTH OF THE JET WITH RADIO OBSERVATIONS. THIS PROPOSAL ENABLES NUSTAR TO OBSERVE IN THIS LUMINOSITY REGIME SINCE THE OBSERVATIONS CAN ONLY BE TRIGGERED THROUGH SWIFT/XRT MONITORING.