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Mystery Effect reply

>Wayne replies:
>If the mystery force doesn't go away, how would it affect long-term
>operation of AO40?  My guess:
>1. Less sleep for the controllers because they have to frequently check the
>ALON/ALAT and adjust the magnetorquing parameters.

As long as the ME is constant, we correct for it in our calculations, 
torques, software, etc.

>2. Assuming AO40 stays spin-stabilized, the ALON/ALAT at apogee would
>occasionally vary by a few degrees, making S1 downlink performance more

As above, we can easily correct for it.  By spinning faster we can reduce 
its effect.  We can even put the magnetorquers into "station keeping" 
mode.  The S/C already has an ME correction that we have added to its code.

>3. Major complication to 3-axis stabilization?

The momentum wheels will have to be "unloaded" more often through the 

>4. Impact on power budget due to frequent magnetorquing?

Not a problem!  The magnetorquers are very low power.

>If the mystery force only acts near perigee, does that rule out propellant
>leak as a possible cause?


BTW:  There is a one word error in my prior post.  I said:

"Remember, to change ALON in the observed direction on a spinning 
spacecraft requires a net "upward" torque (trying to raise
ALAT)."  To be more precise, it requires an "upward" FORCE (on the +Z side, 
trying to push the 400N motor upward and raise ALAT).  The torque vector 
for this force would be 90 degs to that.

  Stacey E. Mills, W4SM    WWW:    http://www.cstone.net/~w4sm/ham1.html
    Charlottesville, VA     PGP key: http://www.cstone.net/~w4sm/key

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