Caution: Creativity at Work!

Last week NASA released some new pictures from the Cassini probe. In particular, I was rather stricken by this photo of Saturn's eccentric little ice moon, Hyperion.



My first thought was that it looked remarkably like a giant paper wasps' nest, and this led to the idea that Toho Studios has been right all along: the universe does abound in 500-meter-tall flying space insects! Paging Mr. Godzilla!

But when I sent the link to Phil Jennings, he came back with a somewhat more interesting assessment: "Clearly it was hollow before the big hunk slid in. Now, what's the first rule about hollow moons?"

Wow! Thought suggested, synaptic gap bridged, circuit complete, new idea generated! Ka-ching! I don't know why it never occurred to me before that the cheapest way to pack along the deuterium you need for your deep space fusion drive would be simply to accrete it as thick layers of ice on the outside of the hull. Set up a robotic mining operation to carve ice off the surface and convey it inside to the reactor as you require fuel, and as an added bonus all those megatons of ice would work really well as ablative shielding. You could probably even brake the ship just by taking it into a star system at a steep angle and letting the star boil off some of the exterior mass.

As an especially attractive added bonus, any impact with ionizing radiation would simply increase the fusion fuel value of the ice, by increasing the amounts of deuterium and tritium in the mix.

Then, taking it a step further, you could carve ice off the inner (less radiated) surfaces to provide water and oxygen for the crew's quarters -- or if you built the thing with "dirty" ice in the first place and laced the ice with carbon and nitrogen contaminants -- well, between the carbon, hydrogen, oxygen, nitrogen, and heat, you've got everything you need to keep an organic biosphere going.

Of course, to minimize the energy required to keep your harvester robots working on the exterior fuel ice, you'd want to keep them working in small areas and depleting everything useful before they moved on, with the result being that over time, the exterior surface of the ship would come to resemble a vast field pock-marked with semi-spherical craters...

Okay, so how about it? This isn't a Monday Challenge, just a little gedanke experimentieren. Who built it, when, and why? Why is it apparently dead and parked in orbit around Saturn?

And are there any more of them out there?