From: tomswift@cruzio.com   
      
   In article ,   
    henry@spsystems.net (Henry Spencer) wrote:   
      
   > In article <20040217220408.25730.00001105@mb-m04.aol.com>,   
   > Allen Meece  wrote:   
   > >     Maybe a longer and slower glide with less atmospheric compression,   
   > >producing less heat build-up, would be preferable to the high speed plunge   
   > >technique?.   
   >   
   > The former is what the shuttle already does.  And as I noted, it makes   
   > thermal protection considerably harder, resulting in much less robust   
   > systems.   
   >   
   > If you're suggesting making it still longer and slower, that is easier   
   > said than done.  Slowing the process down requires staying up in thinner   
   > air, which in turn requires better gliding performance -- to be technical,   
   > a higher hypersonic L/D (lift/drag) ratio.  Alas, the configuration   
   > changes needed for that tend to make thermal problems worse, not better.   
      
   Henry, maybe you can answer a question I have.  I have been told that   
   the Shuttle's ET would reenter without burning up if steps were not   
   taken to depressurize it before reentry.  Is this true, and if so is it   
   because of its very large surface area compared to its weight?   
      
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