From: root@mauve.demon.co.uk   
      
   Allen Meece  wrote:   
   > <>   
   > So,  this thread has concluded that reentry doesn't have to cook a spacecraft   
   > if the space craft retains enough fuel to stop itself in mid-orbit and drop   
   > straight down.  And release a drogue chute to slow it a bit and then release   
   a   
      
   The "stop itself in mid-orbit" is orders of magnitude harder than   
   the "drop straight down" bit.   
   You need the same amount of propellant to slow down as you do to speed   
   up.   
   You have burnt all the propellant you used to speed up, so you'r kind   
   of stuck.   
      
   > parachute or better yet, a paraglider to fly the rest of the way down.   
   >    Alternatively, the space craft can de-orbit by spreading huge wings to   
   > catch the sparse air molecules in orbit and *slowly* descend, taking a few   
   > *days* to scrub off speed before entering the thicker, lower air.   
      
   No, you can't.   
      
   Once you start slowing down, you need to provide lift to stop yourself   
   falling into the atmosphere.   
      
   In order to get lift, you inherently get drag.   
   At hypersonic speeds, the lift you get is only 2-3 times drag, so you   
   inherently are going to slow down at around 2-3 times slower than   
   you would otherwise.   
      
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