Cassini's non-targeted fly-by of Dione on 14 December 2004 at a range of 72,500 kilometres provided a view of the trailing hemisphere containing the bright 'wispy' features. The 'quick look' data was the gossip of the 5-9 December meeting of the American Geophysical Union in San Francisco, California. Surprisingly, instead of strips of ice that had been extruded from fissures, the bright streaks were found to be grooves whose cliff-like walls of exposed ice were brighter than the 'contaminated' surface.205 The grooves cut, and therefore post-dated, the large craters, but, at least in the area imaged, they were not interrupted by large craters. Since the grooves occurred in terrain that was generally darker than average for this body, the question became the nature of the low-albedo material.
An image taken on 14 December 2004 of the 'wispy' terrain on the anti-Saturn side of Dione.
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