From: henry@spsystems.net   
      
   In article ,   
   Josh Gigantino  wrote:   
   >While building out a TransHab-type inflatable station module, fill one   
   >of the outer layers with up to a meter depth of water. Even 20cm of   
   >H2O should help for day-to-day radiation shielding. This should   
   >provide a very good shelter against solar storms...   
      
   20cm or so of water is a good storm shelter for interplanetary space or   
   high orbit.  (There's no point in having it in LEO, which is largely   
   shielded by the magnetosphere.)   
      
   However, you *don't* want it around your entire living quarters.  For one   
   thing, it's very heavy.  For another, even 1m of water is not enough to   
   stop heavy cosmic rays and all their secondary particles, which means you   
   quite possibly get a higher radiation dose that way than with no   
   shielding.  Unless you can provide complete shielding -- which is probably   
   more like 10t/m^2 than 1t/m^2 -- you want just a compact "storm shelter"   
   area shielded.   
      
   >...Several layers of water bladders could   
   >provide a frozen outer layer and liquids closer to the users - both   
   >more comfortable and warmer...   
      
   Uh, there's no reason why the outer layer would be frozen.  In fact, it   
   would probably be difficult to arrange for it to stay frozen.  Manned   
   modules generate a lot of heat.  (Thermal insulation goes *outside* the   
   pressure shell, for several reasons including the fact that it helps   
   provide micrometeorite protection.)   
      
   >...For use as a storm shelter, assuming the 1m average   
   >shielding, would the hatches/ends need to be blocked off with more   
   >shielding? Would bags of water covering the hatches be enough to block   
   >the omni-directional solar storm particles?   
      
   You would want to block the openings of a storm shelter unless they were   
   bent enough that there was no line of sight from interior to exterior.   
      
   >...Would equpiment   
   >inside such a module be able to survive repeated passes (in a highly   
   >eccentric orbit) through the Van Allen belts?   
      
   That's one environment where shielding along these lines might be useful,   
   although I can't quote numbers off the top of my head.   
   --   
   MOST launched 30 June; science observations running     |   Henry Spencer   
   since Oct; first surprises seen; papers pending.        | henry@spsystems.net   
      
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