Re: starship-design: Re: One way (again...)

[kuo@bit.csc.lsu.edu (Isaac Kuo)]

L. Parker wrote:
>On Wednesday, December 10, 1997 1:53 PM, Kelly St [SMTP:KellySt@aol.com] 
>wrote:

>> The deep space probes like Pioneer, Viking, and Voyager  had multi decade
>> service lives.  Thou thie trivially simple compare to these ships.

>Oh don't get me wrong. I'm not saying we can't design a small system to 
>operate for 20 years without failure. Only that the bigger the system gets 
>the less likely that we can engineer EVERY part to those tolerances and the 
>more likely that cumulative failures of subsystems will eventually add up 
>to major system failure.

While this is true, it's also true that manned missions can perform
maintainance utterly impossible for an unmanned mission.  For
instance, Galileo's high gain antenna that got stock and never
unfurled could have been nudged into place in at most hours if
a human were on site.

>We have had quite a history of such failures already in the space program.

We've also had quite a history of manned missions performing
remarkable maintainance when systems catastrophically failed
unexpectedly.

>> Oo, excelent example.  I forgot about material decays in plastics.

>Isaac still hasn't thought about it...

So far nothing mission critical need be made of plastic.

Since there needn't be any plastic on the ship, why worry about
its disadvantages?

>> Excelant point.  One possible siolution for a star ship would be solder
>> joints  on all seals.

This doesn't solve anything.  The problem is diffusion of gas through
solid metal.  Creating something without leaks isn't the issue,
because it's relatively easy to do this (and you _have_ to do it).

>Isaac hasn't got this one either. Lack of real world experience.

Yes I did.  I explained that the ship would have a thick hull
and that it would be larger than a small tank.  Both of these
proportionately reduce the rate of gas loss (diffusion rate
is reduced by hull thickness and size affects loss rate by
the square/cube law).

As for our lack of real world experience--what were Spacelab and
Mir?
-- 
    _____     Isaac Kuo kuo@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
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