M-DLS multichannel diode laser spectrometer for ExoMars landing platform

Abstract:

A multichannel laser diode laser spectrometer has been proposed as a part of scientific payload onboard Russian landing platform of the ExoMars-2018 mission. Scientific goals of the experiment include precise analysis of chemical and isotopic composition, thermal and dynamical structure of the ambient atmosphere, as well as volatiles in soil samples retrieved in the vicinity of the platform, and their diurnal and seasonal variation during at least one Martian year. The instrument consists of three optical paths and two spectral channels. Optical paths corresponding to a classical laser spectroscopy are organized in high-temperature cell for soil volatiles analysis, and multipass integrated cavity-output spectroscopy (ICOS) cell with an efficient pathlength reaching several km. The third optical path is organized in the free atmosphere by direct Sun observations with heterodyne technique. The latter method allows to retrieve vertical profiles of the observed species and to estimate wind speed profile by Doppler shift of absorption line.
The instrument covers two major spectral ranges; near infrared (1.39-1.65 micron) and mid-infrared (2.67-3.27 micron). In the near-infrared range main CO2 and H2O isotopes are analyzed, including vertical profiling of H2O and winds. In the mid-infrared, the instrument will detect HDO and methane. An unprecedented accuracy corresponding to upper limit of 70 ppt is expected on CH4 in both ICOS and heterodyne channels.