Remote Sensing of Column CO2, Atmospheric Pressure, and Vertical Distribution of Dust and Clouds on Mars using Differential Absorption Lidar at 1.96 µm on an Orbiter

By utilizing progress in millijoule-level pulsed fiber lasers operating in the 1.96 µm spectral range, we propose a novel concept introducing a differential absorption barometric lidar designed for remote sensing of Martian atmospheric properties on an orbiter. Our emphasis is on the online wavelength situated in the trough region of two absorption lines, chosen for its insensitivity to laser frequency variations, thereby mitigating the need for stringent laser frequency stability. Our investigation centers around a compact lidar configuration, featuring reduced telescope dimensions and lower laser pulse energies. These adjustments are aimed at minimizing costs for potential forthcoming Mars missions.

The primary measurement objectives include determining column CO2 absorption optical depth, columnar CO2 abundance, surface atmospheric pressure, as well as vertical distributions of dust and cloud layers. By combining surface pressure data with atmospheric temperature insights obtained from sounders and utilizing the barometric formula, the prospect of deducing atmospheric pressure profiles becomes feasible. Simulation studies validate the viability of our approach. Notably, the precision of Martian surface pressure measurements is projected to better than 1 Pa when the aerial dust optical depth is anticipated to be under 0.7, a typical airborne dust scenario on Mars, considering a horizontal averaging span of 10 km.