Physical state of ices in the outer solar system
Article first published online: 21 SEP 2012
This paper is not subject to U.S. copyright. Published in 2001 by the American Geophysical Union.
Journal of Geophysical Research: Planets (1991–2012)
Volume 106, Issue E12, pages 33315–33323, 25 December 2001
How to Cite
2001), Physical state of ices in the outer solar system, J. Geophys. Res., 106(E12), 33315–33323, doi:10.1029/2000JE001334.(
- Issue published online: 21 SEP 2012
- Article first published online: 21 SEP 2012
- Manuscript Accepted: 13 APR 2001
- Manuscript Received: 25 JUL 2000
Comparison of the identity and abundances of ices observed around protostars and those associated with comets clearly suggests that comets preserve the heritage of the interstellar materials that aggregrated to form them. However, the ability to identify these same species on icy satellites in the outer solar system is a complex function of the composition of the original ices, their subsequent thermal histories, and their exposure to various radiation environments. Our ability to identify the ices currently present on objects in the outer solar system relies upon observational and laboratory, and theoretical efforts. To date there is ample observational evidence for crystalline water ice throughout the outer solar system. In addition, there is growing evidence that amorphous ice may be present on some bodies. More volatile ices, e.g., N2, CH4, and CO, and other species, e.g., ammonia hydrate, are identified on objects lying at and beyond Uranus. Both photolysis and radiolysis play important roles in altering the original surfaces due to chemical reactions and erosion of the surface. Ultraviolet photolysis appears to dominate alteration of the upper few hundred angstroms, although sputtering of the surface can sometimes be a significantly competitive process, dominating on icy surfaces embedded in a strong planetary magnetospheric field. There is growing observational evidence that the by-products of photolysis and radiolysis, suggested on a theoretical basis, are present on icy surfaces.