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Modeling of ice pinnacle formation on Callisto
Author(s) -
White Oliver L.,
Umurhan Orkan M.,
Moore Jeffrey M.,
Howard Alan D.
Publication year - 2016
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1002/2015je004846
Subject(s) - regolith , pinnacle , geology , sublimation (psychology) , weathering , landform , ice wedge , crust , geomorphology , solar system , layering , atmospheric sciences , astrobiology , mineralogy , geophysics , physics , medicine , psychology , oceanography , botany , permafrost , radiation treatment planning , psychotherapist , biology , radiation therapy
Callisto's pinnacle terrain has been interpreted to form through sublimation weathering of bedrock and subsequent deposition of the sublimated ice in local cold traps on peaks and crater rims. To investigate how these processes are affected by environmental parameters, including solar illumination and the composition and concentration of ices in the crust, we employ the MARSSIM landform evolution model and advance its treatment of the physics that underlies the relevant processes. Both ice sublimation and deposition are controlled by surface temperature, which we calculate based on energy contributions from both insolation and thermal reradiation from the surrounding landscape. We perform 4.5 Gyr duration simulations whereby we separately consider and model CO 2 and H 2 O as the crustal ice species. We find that sublimating a crustal content of 10% CO 2 ice (a reasonable but arbitrarily selected value) yields present‐day landform degradation and regolith coverage that is comparable to what is observed on Callisto. In our H 2 O ice simulations we reproduce the essential features of pinnacle ice distribution at both the equator and midlatitudes. Our present nominal crustal H 2 O ice content is 33%, which produces a maximum pinnacle ice thickness of 64 m. Pinnacle height is likely limited by collapse or mass wasting of the ice once it reaches a certain thickness.