SBIR-STTR Award

The innovation proposed here is a digital array gas radiometer (DAGR), a new design for a gas filter correlation radiometer (GFCR) to accurately measure and monitor CO2, CO, CH4, N2O and other key trace gases in the boundary layer from space, aircraft or ground-based platforms. GFCR is a well-known and proven technology for trace gas detection and monitoring. However, its effectiveness in downlooking applications has been limited, primarily because variations in surface albedo degrade the performance. Our DAGR approach builds on traditional GFCR concepts and combines several new key elements: two-dimensional detector arrays, pupil imaging (imaging the aperture), and a novel calibration approach. With these enhancements and appropriate signal processing, the DAGR design overcomes the historical limitations of GFCR in downlooking applications. In addition, this design significantly boosts the sensitivity and expands the dynamic range traditionally available to these sensors. Finally, the innovation provides a calibration technique that nearly eliminates errors due to detector drift effects. The result will be a compact, static, robust system that can accurately measure important boundary layer species from a variety of platforms.

The digital array gas radiometer (DAGR) is a new sensor design for accurate measurement and monitoring of trace gases in the boundary layer from space, aircraft, or ground-based platforms using scattered sunlight. Target gases include CH4, CO, CO2, N¬2O and other species critical to climate science, environmental monitoring and commercial pollution compliance efforts. The DAGR approach builds on traditional gas-filter correlation radiometry (GFCR), a well-known and proven technology for trace gas sensing. The effectiveness of GFCR, however, has historically been limited in downlooking applications primarily because variations in surface albedo degrade its performance. In our Phase I effort, we investigated and demonstrated the ability of the DAGR design to overcome these limitations. With the successful completion of these feasibility studies, the technology has been increased to TRL-3. In the Phase II effort, we will construct and test a prototype DAGR sensor for CH4 detection and monitoring, advancing the technology to TRL-5. CH4 was chosen as our target gas to meet the pressing commercial need for an improved natural gas leak detection system. For NASA, the DAGR prototype will significantly advance the technology needed for future missions such as ASCENDS, GEOCAPE, and GACM. DAGR represents a major advance in using backscattered light for detecting concentrations of key molecular species.