The overall technical goal of this SBIR is the development of a commercially viable, small Unmanned Aircraft System (sUAS) with a passive microwave sensor to enable high resolution mapping of soil moisture content. Current remote-sensing methods for sampling soil moisture often fail to provide measurements with adequate spatial and temporal resolution, or any indication of moisture content at typical root depths. This work involves the integration of existing sensor, airframe, and autopilot technologies to construct a novel sensing platform.  The scientific payload will be  a passive microwave sensor in the L-band to map soil moisture content. The airframe utilized is the Tempest, originally designed for sampling tornadic thunderstorms and is a robust, easy to operate design that can takeoff and land on unimproved surfaces. The avionics will be based on the SwiftPilot system which consists of an autopilot board, wireless link for communication, command and control, ground station, and tablet based user interface.  The SwiftPilot system provides a simple, intuitive interface for conducting sUAS missions making it ideal for scientific applications. Tight integration of the sensor with the sUAS avionics and airframe will enable precise flight control for low altitude missions in the range of 15m-30m above ground level (AGL) enabling the sensor to accurately map soil moisture with a resolution approaching 15m. The PI's working knowledge of the regulatory environment surrounding sUAS will be used to inform the development of the system and associated concept of operations. This will facilitate operation in the national airspace following FAA approval. The technical goal of this Phase I proposal is to design the interfaces; mechanical, electrical, and software required for integration of the sUAS. This will include the design of experiments for testing and validating this unique sensing platform in Phase II to assess the the performance in the desired scientific missions.