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



Whatever is causing the spin-down at perigee, my guess it is produced by
atmospheric drag.  At perigee today, NOVA showed a range of 325 km.  That
is only 202 miles above earth.  Spacecraft at that altitude don't stay up
very long without frequent orbital boost!  Has anyone looked at what
perigee has been doing over the last three months?  I'll bet it is slowly
dropping.  I hope we are able to fire the arc-jets soon enough to raise
perigee beyond the region of atmospheric drag.

I checked the altitude for ISS and it is ~379 km.  Haven't I heard
correctly that periodic firings of the docked supply ships are required to
keep the space station in proper orbit? 

I know I have spoken the unspoken fear on many minds.  Its in the hands of
the controllers and orbital anlaysts.  They surely know these factors
better than I.

Now another hypothesis:  I wonder if the loss of propellent has caused a
unbalance of the mass centroid?  If the center of gravity is off-center,
might this cause a wobble in the spin that drag might act on?  Doppler
should have shown if there is a wobble, I guess.

Ed

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