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What are the fundamental drawbacks to using water ice as an external shell for manned spacecraft?

Jerry McDonald
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  • Spacecraft in general, or pressurised (i.e. human-carrying) spacecraft specifically? It seems like a somewhat odd idea, could you give a bit more background to where the idea comes from or where you would like to take it? – Lightsider Oct 23 '15 at 14:52
  • Am thinking properties of water ice (radiation absorption, abundance, moldable, adhesion, life supporting, etc..) would make it a reasonable outer shell material for manned spacecraft. – Jerry McDonald Oct 23 '15 at 15:00
  • Concept would include "growing" the external shell onto a lattice by accretions of water ice at the cryogenic temperatures of outer planets then returning the craft to work inside Mars orbit and beyond. – Jerry McDonald Oct 23 '15 at 15:31
  • @JerryMcDonald: Eh, time and delta-V. Getting to the outer planets, matching orbit between the ice and the vehicle, getting back... and probably unmanned, as the lengthy travel would be unshielded. – SF. Oct 23 '15 at 16:18

1 Answers1

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Quite a few.

Loss, foremost - water sublimating into space. Sunlight would be turning the craft into a comet anywhere inside Mars orbit.

Not heat tolerant - Ejecting heat produced by the systems is another problem. How not to eject it into the ice shell? Performing a burn with the engines?

Mass - getting all that water into orbit. It's heavy and not a nice structural material.

Brittleness - if you use weak ion engines, that's okay. If you use rocket thrusters, oops. Also, would it need to hold that 1 bar pressure difference or would it need an extra shell?

Reactivity, condensation - it would enable rust in environments with oxygen. You'd have headaches of fighting moisture within the ship.

There are many upsides too (you've mentioned them in the comment) but exposing the water to open space creates far too many headaches and it makes a really lousy structural material. A balloon-like shell filled with water is an idea worth considering. A spaceship made of ice - well, maybe in more distant sci-fi universe.

SF.
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