THE CYCLONE GLOBAL NAVIGATION SATELLITE SYSTEM (CYGNSS) GLOBAL NAVIGATION SATELLITE SYSTEM REFLECTOMETRY (GNSS-R) DATA HAVE BEEN DEMONSTRATED TO BE USEFUL FOR OBSERVING OCEAN SURFACE WIND SPEEDS UNDER HEAVY PRECIPITATION INCLUDING WITHIN HURRICANES SUBSURFACE SOIL MOISTURE AND WETLAND FLOOD INUNDATION AT HIGH SPATIOTEMPORAL RESOLUTION ON A GLOBAL SCALE. AS A RESULT IT MAY BE SUCCEEDED BY A SIMILAR CONSTELLATION WITH ADDITIONAL CHANNELS OPERATING AT MULTIPLE NAVIGATIONAL FREQUENCIES MOST NOTABLY GPS/GALILEO L1 AND L5 TO FURTHER IMPROVE SPATIAL RESOLUTION AND SPATIOTEMPORAL SAMPLING. THE POSSIBLE CYGNSS FOLLOW-ON MISSION INSTRUMENT DESIGN OPERATIONAL TESTS AND SCIENCE DATA IMPACT STUDIES COVERED IN THIS PROPOSAL ADDRESS THE NASA EARTH SCIENCE RESEARCH PROGRAMS SCIENCE GOALS OF WEATHER WATER AND ENERGY CYCLE CLIMATE VARIABILITY AND CHANGE AND SOCIETAL BENEFITS. THE ABILITY OF CYGNSS TO OBSERVE TROPICAL CYCLONES IN ALL TYPES OF PRECIPITATION PROVIDES UNIQUE INFORMATION TO OPERATIONAL AND COMMERCIAL FORECASTERS AND HAS THE POTENTIAL TO BE A VITAL INFORMATION SOURCE FOR DISASTER PREPAREDNESS EFFORTS IN THE FUTURE. THE ADDITIONAL DERIVED SCIENCE DATA PERTAINING TO INLAND FLOODING EXTENT ALSO COULD BE IMPLEMENTED INTO VARIOUS CLIMATE MODELS AND USED AS A HIGH-RESOLUTION DATA SOURCE FOR WATER CYCLE MONITORING AROUND THE WORLD. THESE SECONDARY SCIENCE APPLICATIONS FURTHER SUPPORT THE CAUSE FOR A POTENTIAL FOLLOW-ON MISSION. THE SCIENCE OPERATIONS CENTER (SOC) AT THE UNIVERSITY OF MICHIGAN WHERE THE PROPOSING STUDENT IS STATIONED IS RESPONSIBLE FOR PROCESSING SCIENCE DATA FOR LEVELS 0-4 FROM CYGNSS. ADDITIONALLY THE UNIVERSITY OF MICHIGAN WAS AWARDED AN INSTRUMENT INCUBATOR PROGRAM (IIP) PROJECT BEGINNING IN 2017 TO DEVELOP A TRL-6 GNSS RECEIVER PROTOTYPE WHICH COULD BE USED IN A FUTURE SATELLITE. THE PROPOSING STUDENT HAS ALREADY COMPLETED DETAILED DESIGN AND TESTING WORK FOR THE AMPLIFICATION AND ON-BOARD CALIBRATION STAGES OF THIS GNSS-R INSTRUMENT AS A MEMBER OF THE IIP ENGINEERING TEAM AND WOULD LIKE TO EXTEND THE DEVELOPMENT OF THE INSTRUMENT PAST ITS IIP TERM. THE WORK PROPOSED HERE WILL INCLUDE SIMULATOR DEVELOPMENT FOR THE EXPECTED CONVENTIONAL (CGNSSR) AND INTERFEROMETRIC (IGNSS-R) MEASUREMENT TECHNIQUES USING CYGNSS RAW IF DATA FROM THE SOC AND THE COMPLETED BENCHTOP IIP RECEIVER PROTOTYPE IN YEAR 1 A GROUND-BASED AND AIRBORNE FIELD CAMPAIGN TO ASSESS THE PERFORMANCE OF THE INSTRUMENT USING BOTH TECHNIQUES IN YEAR 2 AND A SCIENCE DATA IMPACT STUDY EXAMINING THE BENEFITS OF A SPACEBORNE CONSTELLATION OF THESE INSTRUMENTS FOR HURRICANE FLOODING SOIL MOISTURE AND/OR CRYOSPHERIC RESEARCH IN YEAR 3