From: damarkley@gmail.com   
      
   On Tuesday, February 16, 2021 at 12:24:28 PM UTC-5, JF Mezei wrote:   
   > Differnt spin to question:   
   >   
   > Assume again, Shuttle at at 300km circular, ISS at 400.   
   >   
   > I know that in normal life, on would accelerate horizontally to raise   
   > orbit.   
   >   
   > Now, what if the shuttle were to aim straight up and fire its engines to   
   > reach 400km altitude? (again in the context of a one shot meet lasting a   
   > few seconds with ISS).   
   >   
   > Would the resulting orbit still be 400*300 or would the Shuttle end up   
   > going lower than 300 at perigee because of the momentum from a harder   
   > fall down from 400 (since it would reach 400 without adding any orbital   
   > velocity) ?   
   >   
   > Is it correct to state that the Shuttle that shot straight up to 400km   
   > from 300 will end up at 400 with far less orbital speed/energy than the   
   > onle who accelerated forwards to convert circular into elliptical   
   > 400*300 orbit, or would they have to be mathenatically the same?   
   >   
   > It *seems* to me that the proper elliptical orbit would have greater   
   > speed because it did add delta V to its orbital speed to get there,   
   > whereas the "straigh up" one didn't. Or did that energy spent shooting   
   > straight up end up somehow being converted into orbital energy?   
   >   
   > Also, in a context where one removes risk-of hitting atmpsphere, would   
   > shooting straight up from 300 to reach 400 yield a new stable orbit   
   > apogee/perigee right away, or would apogee and perigee adjust over the   
   > course of many orbits since the boost to 400 was "unnatural" (aka: not   
   > done by increasing orbital speed).   
      
   Correct me if I am wrong but isn't orbital speed in a circular orbit   
   constant?  And it is not constant in an elliptical orbit?  In the latter, the   
   object moves faster at perigee and slower at apogee, correct?   
      
   Dean   
      
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