Editor's Summary

17 August 2006

A levitating ice cap

Two papers in this issue discuss the remarkable seasonal changes seen at the martian south pole. The ice caps on Mars are composed mainly of frozen carbon dioxide, with unusual dark spots that have been attributed to a clear slab of nearly pure CO₂ ice. Langevin et al. present infrared and visible images from the THEMIS camera on Mars Odyssey that are not consistent with the presence of a thick slab of transparent ice. In the companion paper Kieffer et al. report infrared and visible data that show that the features stay at CO₂ ice temperatures well into summer, and must be granular materials brought up to the surface of the ice. They propose a model involving a translucent, impermeable CO₂ cap in which sublimation occurs at the base, producing high-velocity CO₂ gas flow beneath the ice, levitation of the cap and jets that erupt sand-sized grains through vents.

Letter: No signature of clear CO₂ ice from the 'cryptic' regions in Mars' south seasonal polar cap

Yves Langevin, Sylvain Douté, Mathieu Vincendon, François Poulet, Jean-Pierre Bibring, Brigitte Gondet, Bernard Schmitt and F. Forget

doi:10.1038/nature05012

First paragraph | Full Text | PDF (322K) | Supplementary information

Letter: CO₂ jets formed by sublimation beneath translucent slab ice in Mars' seasonal south polar ice cap

Hugh H. Kieffer, Philip R. Christensen and Timothy N. Titus

doi:10.1038/nature04945

First paragraph | Full Text | PDF (648K)