Carbon Dioxide Clathrate in the Martian Ice Cap

Abstract
Measurements of the dissociation pressure of carbon dioxide hydrate show that this hydrate (CO2 · 6H2O) is stable relative to solid CO2 and water ice at temperatures above about 121°K. Since this hydrate forms from finely divided ice and gaseous CO2 in several hours at 150°K, it is likely to be present in the martian ice cap. The ice cap can consist of water ice, water ice + CO2 hydrate, or CO2 hydrate + solid CO2, but not water ice + solid CO2.