Compact Methane Sensing Lidar for Unmanned Aerial Vehicles

Even though gaseous methane (CH4) is a comparatively sparse constituent in Earth?s atmosphere, it is the third most impactful greenhouse gas after water vapor and carbon dioxide, and the second most important in terms of anthropogenic drivers. Methane is some 60 times more effective than CO2 in absorbing long-wavelength radiation, because the methane absorption lines in that part of the spectrum are less saturated and have less overlap with water vapor lines. Natural and agricultural sources of methane continue to dominate, but are difficult to separate and quantify. World-wide, rice cultivation, biomass burning, ruminant farm animals, and fossil fuel mining and usage have long been the most powerful drivers, but with climate change these sources could be dwarfed in the future by the release of enormous quantities of methane from melting permafrost and/or methane hydrates currently buried deep in ocean sediment. Innovative new remote sensing technologies need to address the atmospheric methane concentration measurement problem for NASA and other applications. Beyond Photonics proposes to investigate specific very compact pulsed lidar designs near the 1.645-micron wavelengths of interest by NASA for atmospheric methane (CH4) and potentially water vapor in the same nominal wavelength region. Specifically, methane concentration from moderate-sized unmanned aerial vehicles of NASA?s choice will be a focus; this application puts particular emphasis on decreasing size, weight, and prime power (SWaP) and eliminating active laser component cooling. Particular emphasis will also be placed on ensuring that the lidar designs are compatible with scaling to space qualification in future such programs. Emphasis will also be placed on technical approaches with good operational flexibility in terms of pulse energy and duration, frequency agility, and application to other IR and SWIR wavelengths.