From: sylvia@email.invalid   
      
   On 22/11/2022 10:12 am, JF Mezei wrote:   
   > Watched a NASA video of the Orion going around moon. During this time,   
   > it appeared to do a burn to lower its altitude (I assume thrust aimed to   
   > send it towards moon surface) to create a very very elliptical orbit. No   
   > "live" coverage because that happened while moon was between Orion and   
   > Earth.   
   >   
   > So if you create an elliptical orbit where perigee is on far side of   
   > moon and apogee is somewhere between Earth and Moon, and the goal is   
   > flip this 180° so apogee is on far side of moon (to get the furthest a   
   > manned vehicle has ever been from Earth) what sort of manoeuvers/burns   
   > are needed?   
   >   
   >   
   > Or did I totally misunderstand the burn that was done today?   
      
   The general rule is that you do the burn at the opposite end of the   
   orbit from the bit you're trying to change. So if you want to change the   
   high part of the orbit, the apoapsis [*], then you do the burn at the   
   low point, the periapsis, and vice versa.   
      
   The initial burn behind the moon is done to get into orbit. Since that   
   is inevitably the initial periapsis, it determines how high the initial   
   apoapsis is.   
      
   I don't know that there's an efficient way to swap the periapsis and   
   apoapsis in the short term. But wait two weeks, and it will happen   
   anyway, as the Moon orbits the Earth.   
      
   Sylvia   
      
   [*] Apogee and perigee relate specifically to orbits about the Earth.   
   For more info see https://en.wikipedia.org/wiki/Apsis   
   There's also https://www.thefreedictionary.com/pericynthion   
   and https://www.thefreedictionary.com/apocynthion   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)