Encyclopedia of Planetary Landforms

2015 Edition
| Editors: Henrik Hargitai, Ákos Kereszturi

Cryptic Region

Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-3134-3_93

Definition

A region of low (<0.4) albedo within the southern seasonal cap on Mars that remains near the CO2 sublimation temperature (Kieffer et al. 2000) (≈145 K) and displays weak CO2 ice and H2O ice signatures (Langevin et al. 2006).

Synonyms

Cryptic terrain

Formation

During the southern polar cap’s recession (Ls = 180–270°), the seasonal south polar cap retreats continuously and asymmetrically around the geographic pole, leaving a prominent albedo feature on the seasonal cap that appears almost as dark as bare ground, yet remains cold (−135 °C) because there is a thick layer of CO2 ice under an opaque dust cover. The region occupies the same area year by year (Titus et al. 2003).

The low albedo of the material cover in the cryptic region indicates that a large fraction of the solar radiation is being absorbed in or beneath (Kieffer 2000) the surface.

When the Sun rises seasonally, temperatures remain near the CO2frost point, but albedos slowly increase initially and then drop...

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References

  1. Hansen CJ, Thomas N, Portyankina G, McEwen A et al (2010) HiRISE observations of gas sublimation-driven activity in Mars’ southern polar regions: I. Erosion of the surface. Icarus 205(1):283–295CrossRefGoogle Scholar
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  3. Kieffer HH (2003) Behavior of solid CO2 on Mars: a real zoo. Sixth international conference on Mars, Pasadena, California #3158Google Scholar
  4. Kieffer HH, Titus TN (2001) TES mapping of Mars’ north seasonal cap. Icarus 154(1):162–180CrossRefGoogle Scholar
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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.NASA Ames Research Center/NPPMoffett FieldUSA