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

    loading  Checking for direct PDF access through Ovid


The seasonal polar ice caps of Mars are composed mainly of CO2ice1,2. A region of low (<30%) albedo has been observed within the south seasonal cap during early to mid-spring3,4. The low temperature of this 'cryptic region' has been attributed to a clear slab of nearly pure CO2ice, with the low albedo resulting from absorption by the underlying surface4. Here we report near-infrared imaging spectroscopy of the south seasonal cap. The deep and broad CO2absorption bands that are expected in the near-infrared with a thick transparent slab of CO2ice are not observed. Models of the observed spectra indicate that the low albedo results from extensive dust contamination close to the surface of a CO2ice layer, which could be linked to atmospheric circulation patterns5,6. The strength of the CO2absorption increases after mid-spring, so part of the dust is either carried away or buried more deeply in the ice layer during the CO2ice sublimation process.

Related Topics

    loading  Loading Related Articles