Observations of the northern seasonal polar cap on Mars: I. Spring sublimation activity and processes

Hansen, C.J.; Byrne, S.; Portyankina, G.; Bourke, M.; Dundas, C.; McEwen, A.; Mellon, M.; Pommerol, Antoine; Thomas, Nicolas (2013). Observations of the northern seasonal polar cap on Mars: I. Spring sublimation activity and processes. Icarus, 225(2), pp. 881-897. Elsevier 10.1016/j.icarus.2012.09.024

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Spring sublimation of the seasonal CO2 northern polar cap is a dynamic process in the current Mars climate. Phenomena include dark fans of dune material propelled out onto the seasonal ice layer, polygonal cracks in the seasonal ice, sand flow down slipfaces, and outbreaks of gas and sand around the dune margins. These phenomena are concentrated on the north polar erg that encircles the northern residual polar cap. The Mars Reconnaissance Orbiter has been in orbit for three Mars years, allowing us to observe three northern spring seasons. Activity is consistent with and well described by the Kieffer model of basal sublimation of the seasonal layer of ice applied originally in the southern hemisphere. Three typical weak spots have been identified on the dunes for escape of gas sublimed from the bottom of the seasonal ice layer: the crest of the dune, the interface of the dune with the interdune substrate, and through polygonal cracks in the ice. Pressurized gas flows through these vents and carries out material entrained from the dune. Furrows in the dunes channel gas to outbreak points and may be the northern equivalent of southern radially-organized channels ("araneiform" terrain), albeit not permanent. Properties of the seasonal CO2 ice layer are derived from timing of seasonal events such as when final sublimation occurs. Modification of dune morphology shows that landscape evolution is occurring on Mars today, driven by seasonal activity associated with sublimation of the seasonal CO2 polar cap.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences

UniBE Contributor:

Pommerol, Antoine and Thomas, Nicolas

Subjects:

500 Science > 530 Physics

ISSN:

0019-1035

Publisher:

Elsevier

Language:

English

Submitter:

Cléa Serpollier

Date Deposited:

14 Aug 2014 10:03

Last Modified:

08 Oct 2015 09:29

Publisher DOI:

10.1016/j.icarus.2012.09.024

BORIS DOI:

10.7892/boris.46246

URI:

https://boris.unibe.ch/id/eprint/46246

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