DPS 2001 meeting, November 2001
Session 37. Galilean and Other Outer Planet Satellite Posters
Displayed, 9:00am Tuesday - 3:00pm Saturday, Highlighted, Friday, November 30, 2001, 9:00-10:30am, French Market Exhibit Hall

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[37.04] Europa, Convection, Tidal Heating, and Astrobiology

A.C. Barr, R.T. Pappalardo (LASP, U. Colorado, Boulder), S. Zhong (Dept. of Physics, U. Colorado, Boulder)

Whether or not solid state convection has occurred on Europa, and the implications for formation of surface features, are important to understanding the satellite's geological history and its potential to harbor life. Our preliminary results using a numerical finite element model of convection (Citcom) [Moresi, et. al, 1997] show that convection can recycle material between the ~7-km-thick convective stagnant lid and a sub-surface ocean on short 105 year time scales. However, in order for convection to form the array of surface geology on Europa and potentially sustain a radiation-driven ecosystem, some heat source must have been present at shallow depths in the ice shell. We are in the process of generating improved parameterizations of tidal heat within Europa's ice shell, and studying the influence on the convection pattern, specifically the thickness of the convective stagnant lid.

It is likely that tidal heating affects the internal temperature within the ice shell, but we conclude it is not likely to cause thermal runaways that allow diapirs to pierce the stagnant lid. The dissipation of tidal heat is proportional to the tidal strain rate which varies over wavelengths of approximately 2400 km. Short-wavelength (10's to 100's km) tidal heating may be caused by structures in the ice shell (such as a rising diapirs), but the majority of tidal energy will be dissipated at wavelengths close to the wavelength of tidal forcing.

We have embarked on calculations of the spatial power spectrum of Europa's tidal forcing using the applied tidal potential and non-Newtonian rheology of ice, in order to more accurately parameterize tidal heating as a function of depth in the floating ice shell.

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