M-DLS - a multichannel diode laser spectrometer for Martian studies

A concept of Martian atmosphere and soil volatiles study was developed on the basis of diode laser spectroscopy by collaboration of IKI RAS, MIPT, GPI RAS, University of Reims (France), University of Cologne (Germany), and University of Edinburgh (Great Britain). An experiment, named as M-DLS, has been proposed for the stationery Landing Platform scientific payload of the ExoMars-2018 mission. The M-DLS instrument is targeted to long-term studies of: chemical and isotopic composition of atmosphere near the Martian surface, and its diurnal and seasonal variations; Martian soil volatiles at the location of the Landing Platform; integral chemical and isotopic composition of Martian atmosphere at low scales of altitude at the Landing Platform area, and its variations in respect to local time at the day-light; thermal and dynamic structure of the Martian atmosphere. The M-DLS studies are based on regular measurements of molecular absorption spectra in the IR range along several optical path trajectories, including: a suite of ICOS optical cells of up to 1 km effective optical path, which are directly linked to the ambient atmosphere; a capillary closed-volume optical cell, which is linked to pyrolytic output of a proposed MGAS instrument (Martian Gas Analytic Suite); direct Solar observation open atmosphere path of heterodyne measurements, which is co-directional with the open path line of sight of a proposed FAST instrument (Fourier spectrometer for Atmospheric Components and Temperature). The M-DLS measurements will be carried out in series of narrow-band 2 cm (-1) wide intervals with spectral resolution of 3 MHz ( 0.0001 cm (-1) ), providing for fine recording of molecular absorption line contours. By measurement of H _{2}O and CO _{2} molecules diurnal and seasonal variations and their isotope ratios D/H, (18) O/ (17) O/ (16) O, (13) C/ (12) C, of soil volatiles H _{2}S, NH _{3}, C _{2}H _{2} and others, we expect to receive data for specifying of physical and chemical interactions between surface and atmosphere of Mars. Variations of H _{2}O and CO _{2} vertical profiles and other atmospheric parameters will be recorded during one Martian year. Continuous measurements near the surface and in the atmospheric column at the fixed point of landing will contribute into the campaign of methane search in the Martian atmosphere.