From: heller@deepsoft.com   
      
     "Chung Leong" ,   
     In a message on Sat, 10 Jan 2004 13:54:26 -0500, wrote :   
      
   "L> Bar the development of some revolutionary technology, is it realistic to   
   "L> think that we can land on Mars and come back?   
   "L>   
   "L> Say we want to bring a piece of Martian rock back to Earth. A lander   
   "L> carrying a rover and an ascent module would land on the planet. The rover   
   "L> would move about, pick up a rock, and bring it back to the ascent module.   
   "L> The module is then launched back into space to rendezvous with a return   
   "L> vehicle.   
   "L>   
   "L> It seems to me that the size of lander would be prohibitively large, as the   
   "L> ascent module would need to carry enough fuel to enter into Martian orbit.   
   "L> Compared to the Moon's, Mars' gravity is much stronger. Mars also has an   
   "L> atmosphere, which means thermo-shieldings on both the lander and the ascent   
   "L> module.   
   "L>   
   "L> The return vehicle would be fairly large too, as it needs to carry fuel for   
   "L> returning to Earth. In addition, it would carry the reentry module and   
   "L> equipment for monitoring the Martian atmosphere. Even if we use two   
   "L> launches, the rockets used to carry them into space would be gargantuan.   
      
   This would depend on how how high an orbit the assent module would need   
   to achieve -- assent module itself could also be abandoned, once the   
   crew and samples transfer to the return vehicle.  One possibility would   
   be a several vehicle approach -- sending the return vehicle and/or its   
   fuel separately from the landing vehicle.  We have proven the ability   
   to get unmanned stuff to Mars and then spot it with a reasonable degree   
   of accuracy.   
      
   Note: if the Mars transit vehicles were assembled and launched from   
   Earth orbit (or from a Lunar orbit) there would be various economies   
   realized, since the ships going to/from Mars would not have to contend   
   with Earth gravity well or Earth's atmosphere.   
      
   "L>   
   "L> Perhaps our current approach to Mars exploration is the only way for the   
   "L> foreseeable future?   
   "L>   
   "L>   
   "L>   
      
                                        \/   
   Robert Heller                        ||InterNet:   heller@cs.umass.edu   
   http://vis-www.cs.umass.edu/~heller  ||            heller@deepsoft.com   
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