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CX2SA > SAT 29.08.04 18:40l 42 Lines 1705 Bytes #999 (0) @ AMSAT
BID : ANS-242.01
Read: DG6OU OE1DMB GUEST
Subj: AO-40 Orbit Observations
Path: DB0FHN<DB0FOR<DB0SIF<DB0EA<DB0ACC<DB0FBB<DB0GOS<DB0EEO<DB0RES<ON0AR<
ZL2BAU<IW2ESA<IZ0AWG<PY1AYH<CX2SA
Sent: 040829/1420Z @:CX2SA.LAV.URY.SA #:6608 [Minas] FBB7.00e $:ANS-242.01
From: CX2SA@CX2SA.LAV.URY.SA
To : SAT@AMSAT
AMSAT News Service Bulletin 242.01
>From AMSAT HQ SILVER SPRING, MD.
August 29, 2004
To All RADIO AMATEURS
BID: $ANS-242.01
Peter Guelzow, DB2OS, reports that Victor Kudielka, OE1VKW did an
analysis some weeks ago and was the first to discover some odd changes
in the Mean Motion of AO-40.
It appears that the eccentricity may have changed, but it is also
influenced by other effects and can not be used alone to evaluate
possible changes in AO-40's orbit. Viktor has some expanded diagrams of
mean motion and eccentricity, as well as for the heights of peri- and
apogee and their velocities on his home page:
http://cacofonix.nt.tuwien.ac.at/~oe1vkw/ao40/2004.html
Viktor 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"
Peter continues, "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?" Peter added. "The 'thrust' phase is also much
longer than the battery event, not only a few hours or days.
Perhaps,could be smoothing/manipulation of the NORAD data too. There is
room for a lot of speculation."
Peter concluded, "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."
[ANS thanks Peter, DB2OS for the above information]
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