D
dmjspace
Guest
More Deep Impact news was reported in <i> Science </i> recently.<br /><br />Some disappointing news for the "dirty snowball" model:<br /><br />Only 15 millionths of the surface area of the comet showed evidence of water ice. That's right: a mere 0.000015 of the surface was water ice. <br /><br />According to the paper's authors:<br /><br /><i> The surface area of Tempel 1 is roughly 45 square miles or 1.2 billion square feet. The ice, however, covers roughly 300,000 square feet. And only 6 percent of that area consists of pure water ice. The rest is dust. </i><br /><br />Comets are supposed to be snowballs. Not dust. These findings are consistent with earlier reports from the Deep Impact team that the impact ejecta showed a 10-1 dust-to-vapor ratio.<br /><br />It's pretty clear that comets are not what they were envisioned to be when the dirty snowball model was invented.<br /><br />Instead, they are incredibly dark, dusty bodies with characteristics statistically similar to asteroids, a fact consistent with the competing model of comet and asteroid formation, the EPH.<br /><br />(Regarding my edit...Sorry. In my original post I errantly overestimated the detected water content by a factor of ten.)