NASA's Cassini spacecraft has made its fourth and final close flyby of Saturn's second largest moon Rhea. The probe came within 640 miles of the moon and snapped a dozen closeup images.
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http://www.space.com/14922-photos-saturn-moon-rhea.html (http://www.space.com/14922-photos-saturn-moon-rhea.html)
Fascinating. Awe inspiring to see a human built camera going out to take a picture of a fast moving object 1,2 billion miles away from Earth and being able to get near enough to take close-ups. And people say math is pointless :)
You can see the Rhea Monorail line in that second picture.
There's no scale, but there's a rill (that's what it looks like) pretty much like that on our own moon.
Rill hopping time? Pluto Nash anyone?