WE PROPOSE A 50 KS OBSERVATION OF THE GALACTIC MICROQUASAR GRS 1758-258 WITH NUSTAR TO OBTAIN A HIGH QUALITY HARD X-RAY SPECTRUM IN THE LOW-HARD STATE. AN OBSERVATION WITH SUZAKU HAS REVEALED THE PRESENCE OF A RELATIVISTIC WIND (V ~ 0.1C). HERE WE AIM TO UTILIZE THE EXCELLENT HARD X-RAY SENSITIVITY OF NUSTAR TO CONSTRAIN THE PROPERTIES OF THIS OUTFLOW AND HOW IT RELATES TO THE OBSERVED ACCRETION FLOW GEOMETRY. AS THIS SYSTEM IS KNOWN TO POWER LARGE RADIO JETS ITS STUDY WILL AID OUR UNDERSTANDING OF THE CONDITIONS NECESSARY FOR THE FORMATION OF RELATIVISTIC OUTFLOWS AND HOW THESE RELATE TO THE ACCRETION GEOMETRY IN THE LOW-HARD STATE.