Derivation of martian surface slope characteristics from directional thermal infrared radiometry

Joshua L. Bandfield, Christopher S. Edwards

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Directional thermal infrared measurements of the martian surface is one of a variety of methods that may be used to characterize surface roughness and slopes at scales smaller than can be obtained by orbital imagery. Thermal Emission Spectrometer (TES) emission phase function (EPF) observations show distinct apparent temperature variations with azimuth and emission angle that are consistent with the presence of warm, sunlit and cool, shaded slopes at typically ∼0.1 m scales. A surface model of a Gaussian distribution of azimuth independent slopes (described by θ-bar) is combined with a thermal model to predict surface temperature from each viewing angle and azimuth of the TES EPF observation. The models can be used to predict surface slopes using the difference in measured apparent temperature from 2 separate 60-70° emission angle observations taken ∼180° in azimuth relative to each other. Most martian surfaces are consistent with low to moderate slope distributions. The slope distributions display distinct correlations with latitude, longitude, and albedo. Exceptionally smooth surfaces are located at lower latitudes in both the southern highlands as well as in high albedo dusty terrains. High slopes are associated with southern high-latitude patterned ground and north polar sand dunes. There is little apparent correlation between high resolution imagery and the derived θ-bar, with exceptions such as duneforms. This method can be used to characterize potential landing sites by assuming fractal scaling behavior to meter scales. More precisely targeted thermal infrared observations from other spacecraft instruments are capable of significantly reducing uncertainty as well as reducing measurement spot size from 10s of kilometers to sub-kilometer scales.

Original languageEnglish (US)
Pages (from-to)139-157
Number of pages19
JournalIcarus
Volume193
Issue number1
DOIs
StatePublished - Jan 2008
Externally publishedYes

Keywords

  • Infrared observations
  • Mars
  • Photometry
  • surface

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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