HR: 0800h
AN: P31A-0198    [Abstracts]
TI: Pitting within the Martian South Polar Residual Cap: Evidence for Pressurized Subsurface Carbon Dioxide
AU: * Pathare, A
EM: avp@gps.caltech.edu
AF: California Institute of Technology, MC 150-21, Pasadena, CA 91125 United States
AU: Ingersoll, A
EM: api@gps.caltech.edu
AF: California Institute of Technology, MC 150-21, Pasadena, CA 91125 United States
AU: Titus, T
EM: ttitus@usgs.gov
AF: U.S. Geological Survey, 2255 North Gemini Drive, Flagstaff, AZ 86001 United States
AU: Byrne, S
EM: shane@quake.mit.edu
AF: Lunar and Planetary Laboratory, 1541 E. University Blvd Univ. of Arizona, Tucson, AZ 85271 United States
AB: We present observations of small-scale pitting within the Swiss cheese terrain of the carbon dioxide South Polar Residual Cap (SPRC) and consider the implications of their rapid cascade-like evolution. We show that such pitting cascades: (1) only occur near the walls of thick Swiss cheese mesas; (2) rarely occur in polygonally-cracked mesas; and (3) occur far more often in Mars Global Surveyor (MGS) Years 2 and 3 than in MGS Year 1. We propose that pitting results from depressurization of a sealed layer, which requires subsurface heating that cannot be presently maintained by lateral heat conduction. Instead, we attribute the pressurization and heating implied by pitting to a solid state greenhouse initiated by the recent formation of slab CO2 ice during the southern spring and summer of MGS Year 1, which we show is consistent with Thermal Emission Spectrometer (TES) 25-micron band depth measurements of the SPRC over the last three Mars years.
DE: 5422 Ices
DE: 5462 Polar regions
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: Fall Meeting 2005