MICRO-X IS A SOUNDING ROCKET PAYLOAD THAT COMBINES AN X-RAY MICROCALORIMETER WITH AN IMAGING MIRROR TO OFFER BREAKTHROUGH SCIENCE FROM HIGH SPECTRAL RESOLUTION OBSERVATIONS OF EXTENDED X-RAY SOURCES. THE DESIGN AND DEVELOPMENT OF THIS COMPLICATED PAYLOAD HAS BEEN AN ONGOING NASA APRA EFFORT WHICH IS FINALLY COMPLETE AND UNDERGOING INTEGRATION IN PREPARATION FOR LAUNCH IN FEBRUARY 2018. THIS THREE-YEAR PROPOSAL SEEKS FUNDING FOR: (1) SUPPORT OF OUR NASA AND NIST CO-I'S FOR THE FIRST FLIGHT AND FOR ANALYSIS OF THE FLIGHT 1 DATA (2) DESIGN AND IMPLEMENTATION OF PAYLOAD MODIFICATIONS TO OPTIMIZE MICRO-X FOR A DARK MATTER SEARCH AND THE SECOND FLIGHT OF THE PAYLOAD FROM AUSTRALIA IN 2019 AND (3) FLIGHT 2 DATA ANALYSIS. THE SCIENTIFIC PAYLOAD CONSISTS OF A TRANSITION EDGE SENSOR (TES) MICROCALORIMETER ARRAY AT THE FOCUS OF A FLIGHT-PROVEN CONICAL IMAGING MIRROR. MICRO-X CAPITALIZES ON THREE DECADES OF NASA INVESTMENT IN THE DEVELOPMENT OF MICROCALORIMETERS AND X-RAY IMAGING OPTICS. MICRO-X OFFERS A UNIQUE COMBINATION OF BANDPASS COLLECTING AREA AND SPECTRAL AND ANGULAR RESOLUTION. THE SPECTRAL RESOLUTION GOAL ACROSS THE 0.2-3.0 KEV BAND IS 4-8 EV FULL-WIDTH AT HALF MAXIMUM (FWHM). A RECONFIGURATION OF THE PAYLOAD OPTIMIZING FOR GRASP (EFFECTIVE AREA * FIELD OF VIEW) BY REMOVING THE MIRROR AND INCREASING THE FIELD OF VIEW (FOV) ALLOWS THIS VERSATILE SOUNDING ROCKET PAYLOAD TO PERFORM DARK MATTER SEARCHES WITH WORLD-LEADING SENSITIVITY AS WELL AS STUDIES OF THE SOFT X-RAY BACKGROUND.