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starship-design: Re: Hull Materials

Hi Kelly,

>>> High melting points may indeed be handy if we're going much higher than
>>> 0.3c, then the temperatures can be similar to those of the Shuttle's
>>> shield when entering orbit.
>Does this mean my litium-6 sail and fuel plug will have a heating problem?
> Cruise speed was supposed to be over .4 c.

Yes, I think it will have a problem.

The number (6000Watt/m^2) I mentioned assumes that all radiation is
transferred into heat. To do that, a certain amount of stopping power is
necessary. That is, the shield should be thick enough.
It seems that lower energy protons will loose their energy rather fast,
actually faster than one would realize: A 10MeV proton will come to a
complete "standstill" after only 60 micrometers of aluminium.
My table/formula is only valid upto 10MeV protons, so I can't be sure about
what happens when one encounters a 80MeV proton (the energy of a proton at
0.4c), but I assume it will not lessen the problem.