XPost: sci.space.shuttle   
   From: root@mauve.demon.co.uk   
      
   In sci.space.tech Henry Spencer  wrote:   
   > In article ,   
   > Gordon D. Pusch  wrote:   
   >>>> The problem is that Hubble only has, what, 3 of it's   
   >>>> original 6 gyroscopes still working...   
   >>   
   >>In this particular context, "gyro" actually means "reaction wheel."   
   >   
   > No, actually, "gyro" means "gyro" here.  It's the high-precision sensors   
   > that are giving trouble.  The gyrodynes (I think) that actually produce   
   > torque to rotate Hubble have been reliable.   
      
   There seems to be talk on various pages about "2 gyro mode".   
   How degraded is this?   
   Were the gyros brought down, and if so, did they all fail the same way?   
      
   How long can the thing run open-loop? Are the gyrodynes "noisy", and this   
   has to be nulled out over the short term.   
      
   Might there be a way of just using star-tracking, although it   
   probably would greatly restrict the target list.   
      
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