SCIENTIFIC RATIONALE AND OBJECTIVES. THE CYCLONE GLOBAL NAVIGATION SATELLITE SYSTEM (CYGNSS) HAS THE PRIMARY OBJECTIVES TO QUANTIFY WIND FIELDS WITH IMPROVED TEMPORAL AND SPATIAL SAMPLING DURING THE EVOLUTION OF TROPICAL CYCLONES (TC) AND MEASURE ALL-WEATHER WIND SPEED WITHIN THE EYES OF THE CYCLONES TO ENHANCE THE UNDERSTANDING OF PHYSICS OF CYCLONES TOWARDS IMPROVING CYCLONE FORECASTING.