A compact, lightweight, and low power diode laser sensor will be developed for atmospheric methane detection on small unmanned aerial vehicles (UAVs). The physical specifications of this sensor will be considerably smaller than current NASA laser sensors. The smaller sensor specifications will enable use of carrier UAVs that are similiar in size to a large model aircraft. Using smaller UAVs for measurements will result in large cost savings. The proposed sensor will use an open path optical system that will provide superior spatial resolution in the measurements.