A 3-d Aerosol Profiling Lidar for Planetary Rover Missions

Introduction: Existing remote sensing techniques provide limited information on vertical profiles of dust and cloud distributions in Martian atmosphere. Lidar on PHOENIX mission to Mars demonstrated high vertical resolution aerosol profiling capability [1]. A conceptual study is presented for an advanced 3-D profiling lidar for aerosols and clouds. This instrument will have a form factor suitable for future Mars and other planetary lander and rover missions. This instrument can be adopted as part of combined surface Ra-man/lidar active remote sensing system package [2]. It leverages developments of a compact Nd:YAG laser, a photon counting APD detector and other lidar system developments over the past two decades. With a laser output power of more than an order of magnitude greater than the PHOENIX lidar, multi-wavelength (355, 532, and 1064 nm) output, high sensitivity detector , and polarization sensing capability this instrument is suitable to profile aerosol and clouds up to the Martian tropospause and for improved characterization of aerosols and clouds. These capabilities enable new investigations of climate, atmospheric transport and dynamics. The instrument concept, its sensitivity and predicted precision are presented in this paper. Science Background: Lidar remote sensing provides a unique capability for atmospheric studies involving: 1) ranging, 2) profiling during day and night, 3) spectral selection to avoid absorption due to interfering species, and 4) straight forward inversion without complex data inversion techniques. Precise altitude ranging of aerosol and cloud profiles is the hallmark of pulsed lidar systems. Backscatter lidar data have been used for the retrieval of aerosol extinction profiles that are associated with the development of convective boundary layer, formation of clouds on top of the boundary layer, and many fine scale features in the earth's atmosphere. This capability can be extended to investigate planetary bodies. The lidar on a rover with a robatic arm or a scanning system, will be able to provide 3-D aerosol backscatter and extinction profiles. The combination of three wavelengths (355, 532, and 1064 nm), and aerosol/cloud depolarization at 532 nm will aid in investigating the differences between dust layers, clouds, ice layers and their phases and their optical properties. Surface-based lidar vertical profiling of Mars dust and ice aerosols should provide the capabilities of 100-500 meter vertical resolutions from the surface to the tropopause for day and night local times. Such a capability would enable a broad range of new climate in