Re: [amsat-bb] AO40 Mean Motion change

[Peter Guelzow <peter.guelzow@xxxxxxxxx>]

Hi Bob and All,

There are no secrets:

Victor Kudielka did an analysis some weeks ago and was the first to 
discover some odd changes in the Mean Motion of AO-40. 
If you check the archive, I mentioned that here a while ago, but also 
said the data is still not good enough for any kind of proof  in 
relation to the battery event... Eccentricity may have changed, but it 
is too much influenced by other effects and can not be used.
The above was also reported in public to the audience at the AMSAT-UK 
Colloquium and I have asked Ken Ernandes to also look into this. Ken is 
in touch with Viktor, since we wanted someone else confirming this, 
before going out loudly on AMSAT-BB and elsewhere.

Viktor OE1VKW has some expanded diagrams of mean motion and 
eccentricity, as well as for the heights of peri- and apogee and the 
velocities on his home page:

http://cacofonix.nt.tuwien.ac.at/~oe1vkw/ao40/2004.html

He noted
" I am unable to judge which points are just imprecise measurements and what are the influences of data smoothing or other manipulations. The only big enough effect is the change in mean motion"

If you look carefully on the data, you will see that the "orbit change" already happened
*before* the sudden battery event.  We can only speculate, that it is the battery. It
could be indeed also some remaining fuel?  The "thrust" phase is also much longer than the battery event, not only a few hours or day. Perhaps, could be smoothing/manipulation of the NORAD data too.
Who knows, there is room for a lot of speculation.


Assuming the S/C mass to be 400kg, than this change is due to an impulse of 40 kg m/s
or equal to 5 minutes of hot Arcjet firing.  I have no idea if the battery is capable to do this. Indeed, if it is shortened it will get glowing hot and vent everything..  
What ever caused the short, may still be there?


73s Peter, DB2OS
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