HR: 11:05h
AN: P22A-04    [Abstracts]
TI: Numerical Simulations of Impact Crater Formation and Modification on Icy Satellites
AU: * Turtle, E P
EM: turtle@lpl.arizona.edu
AF: LPL, Univ. of Arizona, Tucson, AZ 85721 United States
AU: Collins, G
EM: g.collins@imperial.ac.uk
AF: Dept. of Earth Science & Engineering, Imperial College, London, SW7 2AZ United Kingdom
AU: Bray, V J
EM: veronica.bray@imperial.ac.uk
AF: Dept. of Earth Science & Engineering, Imperial College, London, SW7 2AZ United Kingdom
AU: Dombard, A J
EM: Andrew.Dombard@jhuapl.edu
AF: Dept. of Earth Science & Engineering, Imperial College, London, SW7 2AZ United Kingdom
AU: Dombard, A J
EM: Andrew.Dombard@jhuapl.edu
AF: Applied Physics Laboratory, Johns Hopkins Univ., Laurel, MD 20723 United States
AU: Schenk, P M
EM: schenk@lpi.usra.edu
AF: LPI, 3600 Bay Area Blvd., Houston, TX 77058 United States
AU: Ivanov, B A
EM: baivanov@online.ru
AF: Institute of Dynamics of Geospheres, Russian Academy of Sciences, Moscow, 117939 Russian Federation
AB: A wide variety of impact crater morphologies has been observed on icy satellites, providing clues to the structural, material and thermal properties of these bodies. However, in order to fully appreciate the implications of crater morphologies for target properties, it is essential to understand which aspects are a direct result of the impact process and which are due to longer-term, post-impact modification. We are using numerical modeling of the collapse, post-impact cooling, and long-term modification, incorporating the effects of impact-heating on viscous relaxation, of craters on icy targets to investigate the processes that lead to features such as central pits and domes and external rings, and to determine the conditions, such as ice temperature and thickness, that are necessary for their formation. We have performed hydrocode simulations of impact cratering in silicate and ice targets to confirm and develop relationships between crater size and the parameters of acoustic fluidization, a mechanism that facilitates target weakening during crater formation (e.g., Melosh and Ivanov, 1999). Modeling to date suggests that the thermal gradient plays a significant role in the final crater morphology (Bray et al., 2005). An accurate model of crater collapse is also important in order to put realistic constraints on post-impact conditions, especially the temperature distribution, and serves as input for finite-element models of crater cooling and long-term modification to assess the effects of viscous creep on post-impact deformation and the timescale over which it operates. By using observed crater morphologies and updated topographic data of fresh craters on Ganymede to constrain models incorporating the effects of post-impact thermal conditions and the evolution thereof we can assess the extent to which, and the conditions under which, craters on the icy satellites have been modified by viscous creep.
DE: 5420 Impact phenomena, cratering (6022, 8136)
DE: 5422 Ices
DE: 6218 Jovian satellites
DE: 6280 Saturnian satellites
SC: Planetary Sciences [P]
MN: Fall Meeting 2005