Rust In Space (Was: Gundam Fleet Composition Examples)
Thu, 07 Jan 1999 20:21:57 -0800

At 19:24 1/6/99 -0800, you wrote:
>Which does beg the question of why space junk in Gundam always looks
>corroded and rusty. There's relatively little water in the colonies
>themselves, and even if the "look" is due to micro-colisions or
>shrapnel. Even energy blasts should only superheat the metal, right?

Exposure to vaccuum can have corrosive effects on some materiels, as some
of their constituent parts boil off. What remains can then react
chemically with other remaindered materials that were previously inert.

(Electrochemical reactions can crop up in the stangest places. My father
was a civilian engineer wo worked for the Navy. He once told me about an
early experiment with aluminum propellers. The attached the propellers to
a barge and left it in the ocean for a few weeks to see how it would
weather. When they got around to checking it, the multi-ton propeller had
vanished completely, but the bolts that held it together were still in
place. Big mystery, until someone (my father, perhaps, although he never
said) noticed that the steel hull of the barge now appeared to be made of
aluminum, at least below the water line. It turned out that seawater is an
electrolyte and the aluminum propellers were dissolved as they
*electroplated* the steel hull!)

Then there's a phenomenon called "vaccuum welding" in which dust particles
are bonded to the surface of materials in space, like micro-barnacles.

In sunlight, the temperature can reach 250 degrees C. In shade, they can
drop to -100 degrees C. A rotating object is alternately roasted and frozen.


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