Original URL: http://www.theregister.co.uk/2005/07/27/enceladus_revealed/

Enceladus revealed as Cassini's photo tour continues

Wish you were here?

By Lucy Sherriff

Posted in Science, 27th July 2005 11:15 GMT

Cassini has sent back another batch of pictures from its tour of the Saturn orbital system. This time, it has snapped the surface of the icy moon Enceladus in unprecedented detail.

Craters and cracks on Enceladus. Image: CICLOPS

Enceladus, discovered in 1789 by Sir William Herschel, is the brightest object in the solar system (not counting the very shiny star in the middle, of course). This has led scientists to theorise that the moon is, or was until very recently, geologically active.

Constantly being resurfaced with fresh ice and snow, by a mechanism that has yet to be determined, has kept the outermost layer bright and white enough to qualify for inclusion in a washing powder advert. Some of the surface could be a mere 100 million years old, according to researchers.

As Cassini flew past on 14 July, it took pictures of the moon's varied surface: craters softened by a covering of ice, and complex fractured terrain, reminiscent of Jupiter's moon, Europa. Some of the areas covered in fissures are entirely free of impact scars.

Great boulders of ice scattered across the surface of Enceladus in the highest resolution images ever taken by Cassini. Image: CICLOPS

The sheer variety of features visible on the surface reveal a history of many different geological processes. Many of the larger craters are softened by a fine-grained frost, and are intersected by multiple tectonic faults.

The geological activity on Enceladus most likely took place in several episodes, and could even continue into the present day. However, there is no direct evidence that the moon is still geologically active.

Cassini also sent back the highest resolution images it has ever taken, revealing the landscape of Enceladus in remarkable detail. Boulders and ice blocks between ten and 100 metres across dominate the surface. The region is unusual, the imagining team says, because it seems to lack the fine-grained frost that covers the rest of the moon. This is further evidence of a young surface.

The researchers have combined the fly-by photography into a movie sequence. You can have a look here. ®

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