TES premapping data: Slab ice and snow flurries in the Martian north polar night

Timothy N. Titus, Hugh H. Kieffer, Kevin F. Mullins, Philip Christensen

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Abstract

In the 1970s, Mariner and Viking spacecraft observations of the north polar region of Mars revealed polar brightness temperatures that were significantly below the expected kinetic temperatures for CO2 sublimation. For the past few decades, the scientific community has speculated as to the nature of these Martian polar cold spots. Thermal Emission Spectrometer (TES) thermal spectral data have shown these cold spots to result largely from fine-grained, CO2 and have constrained most of these cold spots to the surface (or near-surface). Cold spot formation is strongly dependent on topography, forming preferentially near craters and on polar slopes. TES data, combined with Mars Orbiter Laser Altimeter (MOLA) cloud data, suggest atmospheric condensates form a small fraction of the observed cold spots. TES observations of spectra close to a blackbody indicate that another major component of the polar cap is slab CO2 ice; these spectrally bland regions commonly have a low albedo. The cause is uncertain but may result from most of the light being reflected toward the specular direction, from the slab ice being intrinsically dark, or from it being transparent. Regions of the cap where the difference between the brightness temperatures at 18 μm (T18) and 25 μm (T25) is less than 5° are taken to indicate deposits of slab ice. Slab ice is the dominant component of the polar cap at latitudes outside of the polar night.

Original languageEnglish (US)
Article number2000JE001284
Pages (from-to)23181-23196
Number of pages16
JournalJournal of Geophysical Research E: Planets
Volume106
Issue numberE10
DOIs
StatePublished - Oct 25 2001

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ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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