XPost: sci.astro   
   From: j.garry@chem.leidenuniv.nl   
      
   "Rodney Kelp"  wrote in message   
   news:H_2dnQkSbaxcuG3cRVn-qA@adelphia.com...   
   > How do you get a nitrogen atmosphere from a moon that has methane oceans?   
      
   Ask the same question of Earth, how do we have a nitrogen atmosphere with   
   liquid water oceans?   
      
   Briefly, there's every reason to expect materials with similar boiling   
   points (and more importantly, molecular masses) to be present on a given   
   body. Loss mechanisms for the atmosphere can be absorptive (like the CO2   
   that was soaked up to form carbonates on Earth) or 'exhaustive' where the   
   material is lost from the planet by exoatmospheric escape.   
      
   So, if Titan accreted a shedload of methane in its early life (maybe...)   
   then there's nothing to have stopped a comparable cosmic-abundance-worth of   
   nitrogen being trapped too. Do a trawl for 'Lunine' and 'J.S.Lewis' for   
   papers (NASA ADS for starters) and ideas.   
      
   -James Garry   
   (ex Huygens payload tweaker)   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)