Mariner 9 observations of the south polar cap of Mars: Evidence for residual CO₂ frost

Abstract

The first spacecraft observations of the south residual polar cap of Mars were obtained by the Mariner 9 orbiter during the Martian southern summer season, 1971-1972. Analyses of Viking orbiter observations obtained 3 Mars years later have shown that residual carbon dioxide frost was present at the south polar cap in 1977. In this study, Mariner 9 infrared interferometer spectrometer spectra and television camera images are used in conjunction with multispectral thermal emission models to constrain the temperatures of dark bare ground and bright frost regions within the south residual cap. The results provide strong evidence that carbon dioxide frost was present throughout the summer season despite the fact that the residual frost deposits observed by Mariner 9 were less extensive than those observed by Viking.

Water Vapor Saturation at Low Altitudes around Mars Aphelion: A Key to Mars Climate?

“…They also determine that this albedo become increasingly important at higher altitudes (Chassefiè re et al 1992) and latitudes, and for periods of declining distinction between the two seasonal ice caps can account for the observation that CO 2 ice remains over the southern dust loading near the end of the global dust storm activity, due to the reduced settling rates for these small particles. but not the northern residual water ice cap throughout the Mars year (James et al 1979, Kieffer 1979, Davies and The timescale for gravitational settling of 0.1-Ȑm-size dust Wanio 1981, Paige et al 1990). Several mechanisms have hemisphere.…”

Dark material in the polar layered deposits and dunes on Mars

“…Some areas adjacent to the residual frost cap are brighter and less red than the layered deposits, indicating that frost is present below the limit of resolution of the images. Comparison of Mariner 9 imaging and IRIS data suggests that CO2 frost was present in these areas, cooling the surface below its radiative equilibrium temperature [Paige et al, 1990]. In some areas, the presence of frost late into the southern summer appears to stabilize dust deposits, resulting in net deposition [Howard et al, 1982b, Herkenhoff andMurray, 1990a].…”

A search for polycyclic aromatic hydrocarbons over the Martian South Polar Residual Cap

“…During the last few decades, the polar regions have emerged as regions with increased scientific interest. Mars' polar regions, both in the northern and southern hemispheres, have residual caps that survive throughout each hemisphere's respective summer; the North Polar Residual Cap (NPRC) registers as predominately water ice, while the longer, colder winter in the southern hemisphere due to the orbit obliquity means that the South Polar Residual Cap is largely composed of CO 2 ice ( Titus et al, 2003;Byrne, 2009 ) which overlays, and is surrounded by, water ice layers known as Polar Layered Deposits (PLD; Paige et al, 1990;Piqueux et al, 2008 ).…”