THE MASSIVE STELLAR BINARY SYSTEM ETA CARINAE DRIVES STRONG SHOCKS BY COLLISION OF WINDS FROM TWO STARS. FROM NUSTAR OBSERVATIONS OF THE STAR PERFORMED BETWEEN 2014-2017 WE FOUND DEFINITIVE EVIDENCE FOR EXTREMELY HARD NON-THERMAL X-RAY EMISSION. OUR CURRENT BEST EXPLANATION OF THIS COMPONENT IS THE INVERSE-COMPTON (IC) OF SEED STELLAR PHOTONS THAT ARE SCATTERED BY GEV ELECTRONS ACCELERATED BY THE 1ST-ORDER FERMI MECHANISM AT THE WWC SHOCKS. HOWEVER THIS EMISSION DID NOT BRIGHTEN BEFORE PERIASTRON IN 2014 THOUGH IT IS EXPECTED FROM THE STANDARD IC MECHANISM. TO UNDERSTAND THE EMISSION MECHANISM WE PROPOSE ANOTHER NUSTAR OBSERVATION OF ETA CARINAE IN AO4 WHEN THE THERMAL X-RAY EMISSION IS EXPECTED TO INCREASE GRADUALLY TOWARD THE NEXT PERIASTRON PASSAGE.