From: reeuwijk@few.vu.nl   
      
   Henry Spencer  wrote:   
      
   > The most promising reentry protection approach for either of these is   
   > active cooling, either transpiration or circulation, with heat-sink as a   
   > runner-up.  (Ablators are fine too, but I assume you want reusability.)   
   > Heat sinks would be copper, beryllium, or beryllium-based composites.   
   > Active cooling would quite likely be either copper or aluminum, with a   
   > small possibility of steel.  Copper and beryllium don't get along with   
   > seawater, steel is better, aluminum is fine.  Transpiration-cooling   
   > systems would have to worry about clogging of orifices by waterborne   
   > debris, and if they used a porous skin, about it taking up water.   
      
   Delft University in the Netherlands has a test vehicle that uses an   
   internal water cooling system, see <   
   http://dutlsisa.lr.tudelft.nl/dart/introduction.html>. As far as I   
   known, this design has been flown, but landed on land.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)