XPost: sci.space.policy, sci.astro   
   From: gherbert@retro.com   
      
   dexx  wrote:   
   >Is it true that Huygens ceased transmission less than 2 hours after   
   >touchdown? Whilst it was a magnificent achievement to travel so far and   
   >land perfectly, it seems a great shame that the probe was so short   
   >lived.  I'm suprised the designers didnt make it rugged enough and   
   >powered enough to survive several days.   
      
   A lot of people have responded already, but I haven't seen the single   
   most critical point made yet.   
      
   There was no certainty as to what type of surface lay under the   
   clouds.  We knew there were light and dark areas, what the temperature   
   and pressure probably were.  But we didn't know if it was liquid or   
   solid, how much topology was there, whether it was smooth or rough   
   with rocks or ice boulders, etc.   
      
   Designing a probe to survive the landing with high confidence,   
   across the wide range of possible conditions, was just too hard.   
   ESA weren't entirely sure if Huygens was going to survive landings   
   on soil, rocks, or liquid surface anyways.  One of Ralph Lorenz'   
   early focus areas was a paper quantifying the impact parameters   
   and survival chances for the various possible impact surfaces.   
      
   See:   
   	http://www.lpl.arizona.edu/~rlorenz/huygensimpact.pdf   
      
      
   -george william herbert   
   gherbert@retro.com   
      
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