Prof. Thomas Orlando, Georgia Tech

PARTICLE-INDUCED SURFACE PROCESSES
IN THE SOLAR SYSTEM

AACP Seminar Series

Material degradation (i.e. space weathering) in our solar system is known to involve the interaction of solar-wind and magnetospheric particles (ions and electrons) with the surfaces of airless bodies. Since high energy particles create low-energy electrons, most non-thermal degradation/transformations result from the inelastic scattering of secondary electrons. Therefore, the damage is inherently due to electronic excitations and the chemical products formed are often exotic and not easily produced under normal thermal conditions. This is true for complex targets such as minerals on planet, lunar and asteroid surfaces, as well as mixed low-temperature ices on outer solar system grains or within comets.

Our experimental and modeling activities in low-energy (5-50 eV) electron and 5 keV proton induced processes on minerals characteristic of Mercury and Earth’s moon will be emphasized. Specifically, we examine i) the role of magnetospheric “tornadoes” and electron precipitation in contributing to the formation of Mercury’s exosphere [1], ii) the thermal removal of water [2] and the purported formation of water via solar wind impact on regoliths and iii) the oxidation and formation of some complex hydrocarbons during the irradiation of nanoscale ice films on graphitic surfaces reminiscent of interstellar grains.

[1] J. MClain, G. A. Grieves, A. Sprague, D. Schriver, P. Travinicek and T. M. Orlando, in press, J. Geophys. Res.
[2] M. D. Dyar, C. A. Hibbitts, and T. M. Orlando, Icarus, 208, 425, (2010).

For more information contact Prof. Christine Payne (404-385-3125) or Prof. Susanna Widicus Weaver (404-727-4049).