Global Navigation Satellite System (GNSS) signals are scattered when reflected from ocean, land, or ice. GNSS reflected signals a viable candidate for Signal-Of-Opportunity (SOO) passive sensing. GNSS-Reflectometry (GNSS-R) based remote sensing enables environmental scientists a low-cost, wide-coverage measurement system to study the Earth’s environmental processes for conducting experiments in hydrology, climatology, and agriculture studies as well as for measuring parameters such as biomass, Soil Moisture Content (SMC), and Root Zone Soil Moisture (RZSM). IAI has been awarded a contract to develop a GNSS Reflectometer Instrument for Bi-static Synthetic Aperture Radar (GRIBSAR) for measuring earth science parameters. The GRIBSAR technology will be modular, scalable, and meet NASA's goal of developing a multi-channel GNSS-R system to exploit reflected signals as SOO. IAI will develop the complete GRIBSAR system with a passive, highly sensitive GNSS-Rx instrument, GNSS antenna array, Delay-Doppler Map (DDM) and BSAR processing routines, and a flight integration and test plan. GRIBSAR will feature a real-time, high-resolution, data-logging and processing module, allowing for concurrent reception of multiple satellite systems.