Structure of Water Ice in the Solar SystemNearly all of the properties of solar system ices (chemical reaction rates, volatile retention and release, vaporization behavior, thermal conductivity, infrared spectral characteristics and the like) are a direct consequence of ice structure. However, the characterization of astrophysical ices and their laboratory analogs has typically utilized indirect measurements which yield phenomenological interpretations. When water ice is vapor-deposited at 14 K and warmed until it volatilizes in moderate vacuum, the ice undergoes a series of amorphous to amorphous and amorphous to crystalline structural transitions which we have characterized by diffraction methods. These structural transitions correlate with and underlie many phenomena observed in laboratory infrared and gas release experiments. The elucidation of the dynamic structural changes which occur in vapor-deposited water ice as a function of time, temperature and radiation history allows for the more complete interpretation of remote observations of astrophysical ices and their laboratory analogs.
Document ID
20020040977
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Blake, David (NASA Ames Research Center Moffett Field, CA United States)
Jenniskens, Peter (Search for Extraterrestrial Intelligence Inst. Moffett Field, CA United States)