Re: [amsat-bb] AO-40 Update, 2004-01-26

["Vince Fiscus, KB7ADL" <vlfiscus@xxxxxxx>]

Bummer,  Today pass looked good too.  Seems like every time I hear AO-40 it 
Keeps sounding better & Better.



At 09:43 PM 1/25/04 -0500, "Stacey E. Mills" <w4sm@keplerian.com> wrote:

>On orbit 1486, the main battery voltage ran lower than expected.  This was 
>due in part to usage and high solar angle as mentioned previously, but 
>even after the passbands were shut off automatically the voltages did not 
>come back up as expected, in spite of apparently positive battery charge 
>currents.  At the beginning of the eclipse on orbit 1486 at MA =225, the 
>battery voltage rapidly dropped just below the S2 Tx cutoff voltage of 
>24.0 volts and the S2 Tx shut down. to protect the battery and IHU's.  The 
>eclipse ended at about MA=237, approx. 55 minutes later.  We expect the S2 
>Tx to start back up as programmed at MA =2 (as I type this), though it has 
>been known to be  "balky" before on restarts and could require manual cycling.
>
>The command team is investigating this anomaly to determine if the main 
>battery may have developed a single bad (shorted) cell or if there is a 
>problem with the battery set voltage, solar array set voltages, or other 
>problem.  Until we sort this out the passbands will be off for one or more 
>orbits.  If the battery charge or array set points are wrong, they can be 
>changed.  If we have one bad ( shorted ) cell we can reset charge/trigger 
>points to account for this, and we have the completely redundant auxiliary 
>battery, if needed.  We hope to be able to work through this and correct 
>things without too much down time.
>
>We'll update you here as soon as we know more.
>
>--W4SM for the AO-40 Command Team
>
>
>
>--
>  _______________________________________________________________________
>  Stacey E. Mills, W4SM    WWW:    http://www.keplerian.com
>   Charlottesville, VA     PGP key: http://www.keplerian.com/key
>  _______________________________________________________________________
>
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