HR: 1340h
AN: MR23A-1027    [Abstracts]
TI: Similar Sea Ice Behavior Dynamics on Earth and Mars
AU: * Wagner, P
EM: penelopewagner@yahoo.com
AF: University of Texas at San Antonio, Earth and Environmental Science, San Antonio, TX 78249, United States
AU: Ackley, S F
EM: Stephen.Ackley@utsa.edu
AF: University of Texas at San Antonio, Earth and Environmental Science, San Antonio, TX 78249, United States
AU: Xie, H
EM: Hongjie.Xie@utsa.edu
AF: University of Texas at San Antonio, Earth and Environmental Science, San Antonio, TX 78249, United States
AB: Sea ice formation on Mars was postulated by Murray et al 2005, based partially on images showing analogous structures to those reported for the Earth's Polar Regions. Further examination of additional high-resolution imagery from HRSC and HiRise have shown features that resemble sea ice pressure ridges and pile-ups that also have been observed in the Earth's sea ice cover. Ridging features with linear, sinuous, and rectilinear characteristics examined, border darker boundaries that are suggested to be older material. Side-by-side comparisons of Earth and Mars image pairs have indicated highly similar structures in both sets of imagery. From these, we have also made characteristic measurements on for example, the lengths and widths of rafting thrust structures, the "wavelengths" of sinuous ridges, and floe sizes. From these statistics of characteristic structures, we suggest strong similarities in the apparent material behavior on the two planets. Particularly important and more characteristic of sea ice than other materials is that small temperature changes in the material near the melting point (<-5 C) cause large phase changes that result in the highly dynamic transition from ductile to brittle behavior. The ridging comparisons indicate that although the measurements differ, these features require the same two-phase processes of ductile to brittle behavior to form these features. Pile-up features for both planets were evaluated by determining the ratio of the pile-up area to the cleared area to give an indication of the pile-up height. A discrete element pile-up simulation model conducted by Hopkins et al., 1999, proposes that although similar mechanisms are attributed to creating these pile-up features, lower gravity and normal force affect the potential energy, which is proportional to the increased pile-up height on Mars. This unique behavior on both planets provides further evidence that sea ice formed on Mars in an earlier epoch.
DE: 5422 Ices
DE: 5464 Remote sensing
DE: 6225 Mars
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting