Measuring methane on mars using 3.3 μm pulsed lidar from space

Introduction Methane on Mars is of interest both for understanding Martian weather and climate and as a possible signature of anaerobic subsurface life. We present a concept for measuring column CH 4 mole fractions on Mars from space using a 3.3 μm lidar. Methods The lidar transmits online and offline wavelengths sequentially on the strongest CH 4 absorption line in the 3.3 μm band. Combining this measurement with surface pressure from a 2 μm pressure-measurement lidar gives the column CH 4 mole fraction. Results The concept could observe CH 4 in the 1–50 ppb range. The lower end of this range is the detection limit under ideal conditions. Reaching it requires new fiber laser technology that can transmit sufficiently strong pulses. Discussion With this laser development, the concept could be used to study Martian weather and climate and to search for potential signs of anaerobic underground life.