Capability Development for Modeling the Thermal Evolution of
Growing Planetary Satellites, 15-R9701

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Principal Investigators
Robin M. Canup
Amy C. Barr

Inclusive Dates:  04/01/07 – 03/28/08

Background - This project supported the development of a new model of the thermal evolution of planetary moons during their formation through collisional accumulation, or "accretion." As a result of support from this internal research funding, SwRI is now in a unique position to, for the first time, accurately model the thermal evolution of planetary satellites and use this information to test models of their formation. This has placed SwRI in an advantageous position to capitalize on NASA's growing emphasis on exploration on exploration of Earth's Moon and other large icy satellites in the outer solar system.

Approach - Two approaches for calculating the thermal evolution of a growing planetary body were developed: an analytic approach that can constrain the coldest possible state achieved by a growing planet, and a numerical method that can be used to determine realistic accretional temperature profiles.

Accomplishments - Numerical and analytical models of the heating and cooling processes occurring during satellite formation were developed to describe the thermal state of a growing planetary satellite as a function of depth and time. A mathematical framework was developed for determining accretional temperature profiles in planetary satellites by expanding upon existing works to remove the ad hoc parameter h that relates accretional energy to satellite heating. Software was developed to model satellite formation given the dynamical conditions predicted by recent models of satellite formation that allows SwRI researchers to determine whether the currently observed geophysical and geological states of the satellites are consistent with existing formation hypotheses.

Two manuscripts were developed that describe the analytical approaches to model thermal evolution of growing icy satellites, and applications of these approaches to constrain the timing and duration of the formation of Jupiter and Saturn's satellites:

Barr, A. C. and R. M. Canup, Constraints on gas giant satellite formation from the interior states of partially differentiated satellites, Icarus, in press, doi:10.1016/j.icarus.2008.07.004, 2008.

Barr, A. C. and R. M. Canup, Accretional heating of icy satellites, Icarus, in Preparation, 2008.

Three external proposals were submitted to NASA's LASER, Planetary Geology and Geophysics, and National Lunar Science Institute programs. The first has resulted in a newly funded $600,000 project, while the other two proposals are still pending.

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