XPost: sci.space.shuttle   
   From: henry@spsystems.net   
      
   In article <58866faa.0401251157.33cafa83@posting.google.com>,   
   Zoltan Szakaly  wrote:   
   >> The problem is that Hubble only has, what, 3 of it's   
   >> original 6 gyroscopes still working, and it needs two   
   >> to maintain itself and be usable. The gyroscopes wear out...   
   >   
   >Haven't NASA engineers heard of solid state gyros? Such as RLG-s (ring   
   >laser gyro) or FOG (fiber optic gyro).   
      
   Remember that Hubble was designed in the 1970s, and that the specs for   
   those gyros are rather severe.  You might be able to meet them with RLGs   
   now, but the cost of designing and qualifying a new-technology gyro set   
   would be significant.   
      
   Nobody would design a *new* system with those gyros, but for a telescope   
   that wants regular visits anyway for instrument upgrades, it's hard to   
   justify the one-time engineering cost of a retrofit of newer technology.   
      
   Fiber gyros are nowhere near meeting Hubble's specs, although they are   
   very useful for less demanding applications.   
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   MOST launched 30 June; science observations running     |   Henry Spencer   
   since Oct; first surprises seen; papers pending.        | henry@spsystems.net   
      
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