HR: 1340h
AN: P33A-1018    [Abstracts]
TI: South Polar Residual Cap of Mars: Features Within, and Models of, MRO HiRISE Data
AU: * Byrne, S
EM: shane@lpl.arizona.edu
AF: Lunar and Planetary Lab, University of Arizona, Tucson, AZ 85721-0092, United States
AU: McEwen, A
EM: mcewen@pirl.lpl.arizona.edu
AF: Lunar and Planetary Lab, University of Arizona, Tucson, AZ 85721-0092, United States
AU: Team, H
EM: mcewen@pirl.lpl.arizona.edu
AF: Lunar and Planetary Lab, University of Arizona, Tucson, AZ 85721-0092, United States
AB: We report on observations by the High Resolution Imaging Science Experiment (HiRISE) of the south polar residual CO₂ cap of Mars and our related modeling efforts. HiRISE is currently acquiring continuous coverage of this deposit at spatial resolutions of up to 25 cm/px in three separate bands. Several previously undetected features in this CO₂ landscape have been noted such as networks of linear ridges and some examples of mass wasting at the rims of pits within the ice. The thicker portions of the CO₂ ice appear to be composed of roughly 10 layers. Previous MOC observations have shown that features within this landscape are evolving at meters per year. HiRISE observations will resolve the seasonal dependence of this expansion by the end of the Martian year. High resolution color data are currently showing that the seasonal frost is in the process of disappearing over exposures of the layers on the walls of the CO₂ mesas. Although their ablation rates determine that they must be mostly composed of CO₂ ice their color is much redder than expected which could possibly be due to dust contamination or grain-size effects. We have modeled the evolution of this CO₂ landscape and reproduced its evolution as observed by previous spacecraft. These models have also successfully predicted some features visible at HiRISE resolution such as the linear ridges mentioned above. We report on these new observations and how they extend our current models. Model results have already suggested that the thick portions of this CO₂ deposit are likely to be 50- 100 Martian year old, implying that the individual layers observed by HiRISE represent periods of time of order a few Martian years. Global dust storms occur with a similar frequency and may be modulating the behavior of the ice cap.
UR: http://www.lpl.arizona.edu/people/faculty/byrne.html
DE: 5422 Ices
DE: 5462 Polar regions
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting