PI: Jason C. Cook, NASA Ames Research Center, email@example.com
Address: MS 245-6, Moffett Field, CA 94035
CoI: Dale P. Cruikshank, NASA Ames
CoI: Rachel Mastrapa, NASA Ames
CoI: Diane Wooden, NASA Ames
Title: Icy grain halos: amorphous or crystalline water ice?
Abstract: We propose a spectroscopic program to obtain H-band spectra of comets as they approach the sun. Our goal is to detect the icy grain halo that surrounds the nucleus and measure the state of the water ice via the presence (or absence) of the 1.65 (micron) absorption band, attributable to crystalline water ice. Our current understanding of the conditions in the early outer solar system suggest comets should be composed of amorphous water ice. However, some observations can not rule out the grains were observed in the crystalline state because they lack sufficient signal precision. Understanding the state of the ice has large implications on (i) understanding the conditions under which comets formed (\emphi.e. was it warm or cold?), (ii) how impurities such as refractory inclusions (dust grains) or other ices (clathrates) change the rate of crystallization. Together these will be used to develop rules of crystallization for icy bodies in the outer solar system in a more natural setting in which both volatile and refractory contaminants are present at the site of formation.
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