From: oz1sejREMOVETHIS@get2net.dk   
      
   R F L Henley wrote:   
      
   > 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.   
   >   
   > Anyone agree?   
      
   I disagree. Because it is absolutely impossible ever to establish   
   conclusively, that there is not life on Mars. Even if you send millions of   
   rovers and probes, and they dig, drill and examine all they can, you can   
   never *conclusively* rule out the chance that *somewhere*, where we haven't   
   looked, there might be a couple of bacteria.   
      
   Should human activity on Mars bio-contaminate the surface, it should be no   
   problem for a trained biologist to spot the difference between terrestrial   
   microbes and organisms never encountered before.   
      
   What if, e.g., Spirit found bacteria in a soil sample, that was, with 100%   
   certainty, E. Coli? What would the most probable explanation be? That   
   somehow, E. Coli has evolved independently on both Earth and Mars? Or that   
   E. Coli has survived unchanged since the formation of the Solar System? Or   
   that somehow, Spirit became contaminated before Earth departure?   
      
   --   
   Steen Eiler Jørgensen   
   "Time has resumed its shape. All is as it was before.   
   Many such journeys are possible. Let me be your gateway."   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)