XPost: sci.space.policy   
   From: henry@spsystems.net   
      
   In article <33s810hc3o56vu97puj5l9j5ob97t94el5@4ax.com>,   
   Cardman   wrote:   
   >>Hadley Rille, which Apollo 15 landed beside, is almost certainly a   
   >>collapsed lava tube.   
   >   
   >Any photos around of that?   
      
   Lots, I'm sure, but I don't have any URLs handy.   
      
   >Ok, so what would you do with a cavern sized lava tube? As this   
   >surface does not seem so strong if you pressurize one.   
      
   At least for starters, you wouldn't pressurize the whole tube.  But it   
   would provide a shelter, giving a stable thermal environment and screening   
   out radiation and micrometeorites.   
      
   >After all you   
   >said yourself that these have been subject to collapse...   
      
   A segment that's stood up for a few billion years of impacts is likely to   
   continue doing so (although you'd certainly want to study it first).   
      
   >There is also the problem that the walls of this cavern could suck the   
   >moisture out of your air. So it seems to me that you will have to add   
   >artificial walls in order to solve all these problems.   
      
   If you did pressurize the whole tube, almost certainly you would first   
   coat the walls with a sealant of some kind.   
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