From: andrew.gray@dunelm.org.uk   
      
   In article , R F L Henley wrote:   
   > According to BBC Online:-   
   >   
   > President George W Bush will announce proposals next week to send Americans   
   > to Mars   
   >   
   > but . . .   
   >   
   > unless and until we have robotically established conclusively that there is   
   > or is not life on Mars, we can't put humans on the planet because they will   
   > inevitably bio-contaminate it.   
      
   Problem: It is, in theory, easy to prove there is life on Mars - you   
   find some (although doing this is difficult). It's next thing to   
   impossible to prove there isn't; even if you manage to examine a   
   statistically significant amount of the surface (and 'a few square   
   yards' don't really count...) you have to consider the prospects for   
   life in deep rifts, caverns, that sort of thing. As someone has pointed   
   out, since we started sending probes to Mars we've discovered two entire   
   sets of life we didn't think existed on *this* planet...   
      
   [I'm idly reminded of the /Mars/ trilogy; the protagonists find some   
   very scabby lichen at the bottom of a *probably* isolated deep   
   drillshaft, and can't tell if it's indigenous or introduced by them...   
   almost certainly the latter, but they just Can't Prove It. Oops.]   
      
   --   
   -Andrew Gray   
    shimgray@bigfoot.com   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)