From: stellare@NOSPAMPLEASE.erols.com.retro.com   
      
   Lex Spoon wrote:   
      
   >>> Right, but so long as the requirements are moderate, then increasing   
   >>> these specs should simply require more of some components without   
   >>> changing the overall design.  It takes little design effort and only   
   >>> moderate $$'s to simple have *more* board space, or *more* shielding,   
   >>> or *more* overall mass.  It only becomes a problem if you increase the   
   >>> requirements by so much that you need a totally new design approach to   
   >>> power generation or shielding or whatever.   
   >>   
   >> No no no.  I don't design space probes, but it's obvious that this   
   >> argument is not correct. You don't get to increase these specs at all,   
   >> they are constraints.   
   >   
   > If the constraints are fixed, then possibly, though even then there   
   > may well be enough space within the constraints to ease up on the   
   > programmers and put in a garbage collector.   
   >   
   > But why would the constraints be fixed?  Surely these probes go   
   > through an initial design phase where it is sketched out how much   
   > power will be generated and how much shielding will be around and how   
   > much mass is expected and so on.  During that initial sketch, I see no   
   > reason they could not consider copious CPU power as a design option.   
      
   I also see no reason why copious CPU power could be considered as a design   
   option.  Indeed, compared to just a few years back, the rovers do have copious   
   computing power, with a clock rate of 20 MHz, 128 megabytes of DRAM, etc.   
   Many previously flown probes would run off say 8-bit 1802 or 8051 uP, or in   
   the sixteen bit world, an 8086 or MIL-STD-1750A, etc, with perhaps 10s or 100s   
   or kilobytes of memory.   
      
   However, since the purpose of the probes is science, it makes sense to   
   consider allocating resources to scientific instruments.   
      
   The goal of scientific probes is not to fly computers but to return science.   
      
      
   > I am curious what field you work on where constraints are so tight?   
   > In university classes the professors I've seen can barely get through   
   > a description of the waterfall method without poking holes in it.  As   
   > well, they usually start their description with a disclaimer like   
   > "here's a simplistic model that we will start with".   
      
   The field of deep space probes resources are usually quite tight; this is far   
   different than a university classroom.   
      
   --   
   rk, Just an OldEngineer   
   "For a successful technology, reality must take precedence over public   
   relations, for nature cannot be fooled."   
   -- R. Feynman, Appendix F.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)