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Re: AO-40: Plans for April-June 2001

Dr. Jim Akers wrote:

> I will start the discussion with some spectulation about the alon changes.  
> Is it possible that something has come lose on the s/c and is acting like
> a rudder in the very thin atmosphere?

If it is, I guess it will start acting in the opposite direction 
(counterclockwise rather than clockwise) after about 180 degress of 
rotation about the Z-axis, and will show up as the return of decreasing 
magnetorquing effectiveness.

Maybe we should enumerate the possible categories the "unknown force" 
could be in:

1) the one some folks have mentioned, aerodynamic asymetries (are we 
certain that the solar panels haven't partially deployed in some way, 
for instance?)

2) thrusts from leaking on-board fluids (but why strongest at apogee?)

3) some kind of gravity gradient effects (stronger at apogee because the 
altitude is lower and thus we're closer to our primary?)

4 and >4 ) ?????...

I'm under the impression that the inertia wheels aren't spinning right 
now; can anybody confirm that? If so I'm guessing we can rule out any 
kind of an imbalance resulting in a precession force. Once again any 
such theory would have to explain why the force esems to mostly be 
acting at perigee.

Peter is right that the bird is still teaching us things. Wouldn't it be 
nice if we knew what she was teaching *before* we actually learned? :-)

  73 de Maggie K3XS

-----/___.   _)   Margaret Stephanie Leber    / "The art of progress  /
----/(, /|  /| http://voicenet.com/~maggie   / consists of preserving/
---/   / | / |  _   _   _    `  _AOPA 925383/ order amid change and /
--/ ) /  |/  |_(_(_(_/_(_/__(__(/_  FN20hd / change amid order."   /
-/ (_/   '  K3XS  .-/ .-/    ARRL 39280   /___ --A.N.Whitehead ___/
/____ICQ 7161096_(_/_(_/__AMSAT 32844____/ <maggie@voicenet.com>

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