Lite Cycles, Inc. (LCI) proposes to develop a direct-detection Doppler lidar (D3L) technology called ELITE that improves the system optical throughput by more than an order of magnitude. This improvement has the potential to enable wind sensing via Doppler lidar from spaceborne platforms, as well as improving the warning time for on-board clear air-turbulence (CAT) sensors used in commercial aircraft. The ELITE concept will be modeled and tested in Phase-I, and the feasibility for spaceborne implementations will be assessed. A prototype D3L system that utilizes the ELITE technology will be built and tested in Phase-II. The test results will be used to assess the feasibility of ELITE-based spaceborne Doppler lidar.
Potential NASA Commercial Applications: (LIMIT 150 WORDS) On average, one commercial flight encounters significant clear-air turbulence (CAT) every other day. Between 1980 and 1995, the FAA reports CAT encounters injured 316 people and killed two. Doppler lidar is the only known method capable of reliably detecting CAT at ranges necessary to effectively prepare for or evade violent encounters. Experimental coherent-based Doppler lidar sensors are capable of detecting CAT at a range of 10 miles at 20,000 ft, which translates into a 45 second warning time. This meets the threshold-level requirement, and has little commercial utility. Ideally, much greater warning times at objective altitides are required to make a CAT sensor feasible for commercial deployment. Moreover, the costs associated with coherent-based systems make it difficult to achieve commercial viability. Direct-detection Doppler lidars based on the ELITE technology have considerable promise in meeting the objective specifications and cost of commercial CAT sensors.
Potential NON-NASA Commercial Applications: (LIMIT 150 WORDS) Global measurement of tropospheric wind is potentially the most significant contribution of satellite remote sensing to existing global meteorological observations. However, there are large deficiencies in accurate wind measurements over large regions of the world (e.g., oceans), and spaceborne sensors are the only practical means of addressing these deviciencies. The deployment of spaceborne wind sensors would provide critical data on hydrologic and biogeochemical cycles, planetary scale dynamics, atmospheric-oceanic heat transport, as well as critical wind information for improved operational weather forecasting. NASA has been directly involved in the development of wind-sensing lidar technologies to address this need. Direct measurement of horizontal wind vectors in clear air has been demonstrated using lidar from the ground and from aircraft, based on determination of the wind-induced Doppler shift in the backscatter signal. However, the performance of Doppler lidar systems must be dramatically improved to make wind sensing feasible from space-based platforms. The improvements and simplicity of the proposed ELITE technology may provide the enhancements required to enable space-based wind sensing via Doppler lidar.
