XPost: sci.space.tech   
   From: smithm@SPAMBLOCK.com.au   
      
   On Mon, 10 Nov 2003 12:01:58 -0700   
   Hop David  wrote:   
      
   > In _Entering Space_ Robert Zubrin mentions that it would take only a   
   > small amount of Delta V to send Kuiper Belt Objects down to Mars. He   
   > believes comets striking Mars would thicken the atmosphere and raise > the   
   > temperature. (I also seem to recall Kim Stanley Robinson using this > idea   
   > in his Mars trilogy)   
   >   
   > But now in John S. Lewis' _Rain of Iron and Ice_ I read about   
   > atmospheric erosion  by meteorites. Most the atmosphere the other side   
   > of a tangent plane touching the Martian sphere at point of impact is   
   > sent into space.   
   >   
   > So would comets add or subtract to Mars' atmosphere?   
   >   
   > By my calculations KBOs sent on a Hohmann transfer orbit to Mars would   
   > come into Mars orbit at about 9 km/sec. Mars gravity would add another   
   > 5. So I believe a KBO would hit Mars at around 14 km/sec.   
      
   If the impact is vertical then most of the momentum of the impacting object   
   would be absorbed by the martian crust. If the impact is off vertical then   
   more of the momentum would go into the atmosphere but I suspect would be   
   transferred over the whole    
   trajectory of the object.   
      
   I doubt that the mass lost from the atmosphere would be anywhere near as much   
   as delivered by the impacting body.   
   ----   
   Michael Smith   
   Mail address and GPG key available from www.netapps.com.au   
      
   -----BEGIN PGP SIGNATURE-----   
   Version: GnuPG v1.2.1 (GNU/Linux)   
      
   iD8DBQE/sLR0VBAeZyhLJFgRApLMAKCjdHuEEE15G0rIrkcVR2/9a5kCFACbB/Sb   
   AF0j2U/KOI5YoRFMTd05Eu4=   
   =a8XX   
   -----END PGP SIGNATURE-----   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)