High-resolution spectroscopy of the Martian atmosphere: study of seasonal variations of CO O3 H2O and T on the north polar cap and a search for SO2 H2O2 and H2CO

摘要

We describe an observation plan to measure the seasonal variations of: (1) the CO mixing ratio on the Martian polar cap caused by accumulation and depletion of CO during condensation and evaporation of CO$-2$/. The variations may be a factor of 2 - 3, and this effect has never been observed; (2) ozone and water vapor at the north polar cap at the beginning of spring on Mars, where no seasonal measurements were obtained by the Mariner 9 and Viking spacecraft, respectively; and (3) a search of H$-2$/CO, H$-2$/O$-2$/, and SO$-2$/, the latter if present is very important for the Martian photochemistry. The detection limit may be close to few ppb (part per billion) which corresponds to the limit of importance of SO$-2$/ and H$-2$/CO and makes measurable the photochemically predicted amounts of H$-2$/O$-2$/. The beginning of the Martian spring covers the extremal points of the seasonal variations of CO and O$-3$/. Only the next opposition in the current decade provides a good opportunity of observations of these phenomena. We hope to conduct the observations in 2 or 3 narrow spectral ranges between 1.15 and 2.35 $mu@m. They need high spectral resolution $lambda@/$delta$lambda $APEQ 10$+6$/ and a large telescope due to the small visible size of the illuminated polar cap. The combination of the 4 m telescope and Fourier Transform Spectrometer of KPNO is ideal for this problem. The H$-2$/CO, SO$-2$/, and H$-2$/O$-2$/, lines will be measured in the equatorial region by the same instrument at 3.6 and 7.7 $mu@m. These observations will give important new data on the atmospheric photochemistry and dynamics and will support the Mars Observer program to study the polar caps and the general circulation of the atmosphere.