From: alain245@videotron.ca   
      
   On Feb/2/2021 at 13:48, Jeff Findley wrote :   
   > In article <3zeSH.68193$xa.35702@fx47.iad>,   
   > jfmezei.spamnot@vaxination.ca says...   
   >>   
   >> A few days ago, I was reading about the LEM, and found out that they   
   >> were "disposed" of in different ways.   
   >>   
   >> Some were left in orbit around the moon but eventyally crashed in   
   >> unknown locations.   
   >>   
   >> I beleive one was sent to some heliocentric orbit and would still be there.   
   >>   
   >> And the last ones were deliberately crashed onto the moon.   
   >>   
   >> So some questions:   
   >>   
   >> What are the parameters that would cause an orbiting LEM to end up   
   >> crashing on the moon? Is there a thin atmosphere around the moon that   
   >> would slow down an orbiting ship over time?  Orbital precedence that   
   >> would eventually result in some elliptical orbit that becomes more and   
   >> more elliptical till perigy hits the ground?   
   >   
   > The same thing that makes almost all lunar orbits unstable.  The moon's   
   > gravity field isn't uniform.  It's got mascons (mass concentrations).   
   >   
   > https://en.wikipedia.org/wiki/Lunar_orbit#Perturbation_effects   
      
   You forgot a word there.   
   The same thing that makes almost all *low* lunar orbits unstable.   
      
   Most low lunar orbits are unstable because of mascons. High lunar orbits   
   are unstable because of disturbances caused by Earth and the Sun.   
      
      
   Alain Fournier   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)