Mission Update - June 2006
The composition of the nucleus is not uniform
by Lucy McFadden
Results from the Infrared spectrometer in work lead by Lori Feaga of University of Maryland, show asymmetric distributions of both water and carbon dioxide gases in the coma of Tempel 1. The water is enhanced in the sunward direction, where sunlight sublimates water ice. The CO2 is enhanced off of the southern hemisphere of the comet. This suggests that the composition of the nucleus of the comet is not uniform, and is heterogeneous. One of the major objectives of the mission was to determine whether comet nuclei are uniform in composition. The answer is no. Detailed study of these coma asymmetries gives insight to the relative abundances of the dominant molecular components of the inner coma, source regions of the native volatiles, anisotropic outgassing of the nucleus, and the formation and evolution of the nucleus.