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The crystalline state of water ice in the Solar System depends on the temperature history of the ice and the influence of energetic particles to which it has been exposed. We measured the infrared absorption spectra of amorphous and crystalline water ice in the 10-50 K and 10-140 K temperature range, respectively, and conducted a systematic experimental study to investigate the amorphization of crystalline water ice via ionizing radiation irradiation at doses of up to 160 pm 30 eV per molecule. We found that crystalline water ice can be converted only partially to amorphous ice by electron irradiation. The experiments showed that a fraction of the 1.65 mum band, which is characteristic for crystalline water ice, survived the irradiation, to a degree that strongly depends on the temperature. Quantitative kinetic fits of the temporal evolution of the 1.65 mum band clearly demonstrate that there is a balance between thermal recrystallization and irradiation-induced amorphization, with thermal recrystallizaton dominant at higher temperatures. Our experiments show the amorphization at 40K was incomplete, in contradiction to Mastrapa and Browns conclusion (Icarus 2006, 183, 207.). At 50 K, the recrystallization due to thermal effects is strong, and most of the crystalline ice survived. Temperatures of most icy objects in the Solar System, including Jovian satellites, Saturnian satellites (including Titan), and Kuiper Belt Objects, are equal to or above 50 K; this explains why water ice detected on those objects is mostly crystalline.
Our knowledge about the physical processes determining the activity of comets were mainly influenced by several extremely successful space missions, the predictions of theoretical models and the results of laboratory experiments. However, novel compu
This brief review will discuss the current knowledge on the origin and evolution of the nitrogen atmospheres of the icy bodies in the solar system, particularly of Titan, Triton and Pluto. An important tool to analyse and understand the origin and ev
Over the last eight years, the Visual and Infrared Mapping Spectrometer (VIMS) aboard the Cassini orbiter has returned hyperspectral images in the 0.35-5.1 micron range of the icy satellites and rings of Saturn. These very different objects show sign
Water content and the internal evolution of terrestrial planets and icy bodies are closely linked. The distribution of water in planetary systems is controlled by the temperature structure in the protoplanetary disk and dynamics and migration of plan
Identifying the source of Earths water is central to understanding the origins of life-fostering environments and to assessing the prevalence of such environments in space. Water throughout the solar system exhibits deuterium-to-hydrogen enrichments,