"Stability of Amorphous Water Ice on Solar System Bodies: A Key to Thermal History "
Infrared detection of water ice phase can reveal the temperature and radiation history of an the surface. In this presentation, I will describe and quantify the process of amorphization of crystalline ice through lab experiments and computer simulations. I will also show how these measurements can be applied to ground based observations. The amorphous phase of water forms at temperatures less than 130 K, and converts to crystalline at 135 K in an exothermic and irreversible reaction. However, ion irradiation of crystalline water ice in the lab makes the infrared spectrum indistinguishable from that of amorphous ice. The amorphous and crystalline phases have distinctive spectra in the infrared. This model can be applied to different planetary surfaces, using an estimate of the temperature and the radiation environment.