[amsat-bb:74680] AO-40 in critical condition

[Peter Guelzow <peter.guelzow@xxxxxxxxx>]

Dear All,

AO-40 is in a very critical situation at the moment..

Our command team is working hard to get AO-40 back under fully control.

Last night (Orbit #1488, 2004-01-27, 00:57, UTC MA 42) the battery voltage
suddenly dropped from 26V to 14V.  We currently believe, that in some
kind of domino effect more battery cells died shortened.
There is also a report that the Heat Pipes 4+X+Y temperature suddenly
rise from 27°C to 92°C, when a few moments later the voltage went down.
This report is not yet confirmed..

Several stations reported, that around this time the S-Band signal dropped
rapidly. This would be consistent with the low bus voltage, preventing
the S-TX from working properly.  At the moment we assume that the IHU
is still working.

Command stations are trying to send send blind commands to the spacecraft
in an attempt to switch over to the auxiliary battery.

If that does not help, than the IHU will be reseted and loaded with
some software to switch the relays.

It may take some time, perhaps until the sun angle is getting better.

73s Peter DB2OS






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