Carbon Dioxide Sublimation on Iapetus: Exploring the Kinetic Possibilities
Abstract
Although Cassini did not map the northern pole of Iapetus to test the claims of a CO2 polar cap (Palmer and Brown, 2007, Astrophys. Jour., 666, L125-L128), further modeling can determine its likelihood. Recent spectral analysis of the 4.26 micron CO2 absorption feature in the dark material on Iapetus demonstrates that the surface may contain pure, clathrated, or complexed carbon dioxide (Cruikshank et. al., 2010, Icarus, 206, 561-572). We will explore the kinetics behind sublimation from all three possibilities by building upon experimental results of dry ice and CO2 clathrate hydrate sublimation under low temperature and pressure conditions (Leeman et al., 2010, LPSC XLI, 1533; Blackburn et al., 2010, Planet. and Space Sci., 58, 780-791). We will set strict limits on the mass flux of CO2 available from each of these scenarios by applying a new thermal model incorporating albedo from the recent bolometric Bond albedo map that includes coverage of the northern pole from Voyager (Blackburn et al., 2010, Icarus, submitted). While previous sublimation rate estimates have relied on the Langmuir evaporation equation, we contend that this formula sets only the upper limit on the amount of sublimation that can occur. The rate is even further reduced when considering the possibility of CO2 sublimation though an overburden. We will present the implications of this new model on ballistic transport of CO2, stability zones for dry ice, CO2 clathrate hydrate, and complexed CO2, as well as the resident times of a possible CO2 polar cap on Iapetus.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #42
- Pub Date:
- October 2010
- Bibcode:
- 2010DPS....42.0104B