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

Abstract : The seasonal polar ice caps of Mars are composed mainly of CO2 ice(1,2). A region of low (< 30%) albedo has been observed within the south seasonal cap during early to mid-spring(3,4). The low temperature of this 'cryptic region' has been attributed to a clear slab of nearly pure CO2 ice, with the low albedo resulting from absorption by the underlying surface(4). Here we report near-infrared imaging spectroscopy of the south seasonal cap. The deep and broad CO2 absorption bands that are expected in the near-infrared with a thick transparent slab of CO2 ice are not observed. Models of the observed spectra indicate that the low albedo results from extensive dust contamination close to the surface of a CO2 ice layer, which could be linked to atmospheric circulation patterns(5,6). The strength of the CO2 absorption increases after mid-spring, so part of the dust is either carried away or buried more deeply in the ice layer during the CO2 ice sublimation process.
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Contributor : Béatrice Pibaret-Bourdon <>
Submitted on : Thursday, January 29, 2009 - 6:00:20 PM
Last modification on : Friday, January 8, 2021 - 12:16:03 PM

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Y. Langevin, Sylvain Douté, M. Vincendon, F. Poulet, J.-P. Bibring, et al.. No signature of clear CO2 ice from the 'cryptic' regions in Mars' south seasonal polar cap. Nature, Nature Publishing Group, 2006, 442 (7104), pp.790-792. ⟨10.1038/nature05012⟩. ⟨insu-00357235⟩



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