Sublimation kinetics of CO2 ice on Mars

The evolution of the albedo of dark spots observed on Mars polar region

“…On the one hand, the onset of CO 2 ice sublimation in Richardson Crater is a slow process Kossacki and Leliwa-Kopystyń ski, 2004), unable to explain a large decrease in albedo in 23 Sols. On the other hand, Blackburn et al (2010) experiments suggest that the CO 2 ice sublimation rate is about 1.20 mm h À1 . Assuming that CO 2 ice starts to sublimate at L s ¼ 197 and stops at L s ¼ 260 , this would imply the presence of a 2 m thick layer of CO 2 ice.…”

“…Initially, the sublimation rate is small, but increases rapidly. Blackburn et al, 2010 shows that a CO 2 ice layer between 0.3 and 0.5 m thick sublimates in 16 Sols (the time span covered by stage IV). These values are in reasonable agreement with values of about 0.2 and 0.3 m measured at Richardson Crater's latitude by the Mars Orbiter Laser Altimeter (MOLA) (Smith et al, 2001).…”

Locations of thin liquid water layers on present-day Mars

“…As is shown in Blackburn et al (2009), the transmission coefficient is a polynomial fit to the data from Pollack et al (1990) as presented by Rapp (2008). Atmospheric perturbations to the incoming heat flux considered were the indirect solar illumination due to scattering (Q scattering ) and atmospheric thermal emission (Q IR ):…”

“…where f scat (0.02) and f atm (0.04) are the fractional amounts of the relevant flux reaching the martian surface (Schmidt et al, 2009), d is the solar declination, and / is latitude (Kieffer et al, 1977;Applebaum and Flood, 1989;Aharonson and Schorghofer, 2006;Blackburn et al, 2009;Schmidt et al, 2009;Rivera-Valentin et al, 2010;Ulrich et al, 2010;Rivera-Valentin, 2012). The lower boundary condition includes a modest geothermal heat flux from below assigned as 30 mW/m 2 as previously applied by Ulrich et al (2010).…”

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

“…The attenuation of Mars' magnetosphere led to a loss of atmosphere through solar wind interactions, leaving the average temperatures and atmospheric surface pressures much lower than on the Earth ( Johnson et al, 1996;Kass and Yung, 1995;Melosh and Vickery, 1989 ). Liquid water generally cannot exist on the surface of Mars due to low atmospheric temperatures and pressures and both water and CO 2 ice sublimate directly from the solid to vapour phase ( Blackburn et al, 2010 ). The lack of a significant atmosphere on present-day Mars means that the surface is exposed to high levels of UV radiation, which would have a deleterious effect on any biological material on the planetary surface ( Cockell et al,20 0 0 ); However, the annual, seasonal sublimation and deposition of CO 2 ice on the SPRC leads to an unique surface feature known broadly as 'Swiss Cheese Terrain' (SCT), characterised by flat floored, circular depressions that can intersect to form intricate patterns reminiscent of Emmental Swiss Cheese ( Malin et al, 2001 ).…”