Hi Peter, thank you very much for the informations regarding AO-40 and your effort on this.....fingers crossed.... 73" Frank IW4DVZ
-----Messaggio originale----- Da: [email protected] [mailto:[email protected]] Per conto di Peter Guelzow Inviato: domenica 2 marzo 2008 20.32 A: [email protected] Cc: [email protected] Oggetto: [amsat-bb] Re: recent AO-40 efforts?
Hi Don and Auke,
I believe AO-40 was designed by AMSAT to not allow both sets of batteries
to
be disconnected. We should have learned with AO-7 that every satellite should be able to work on solar power alone as eventually all batteries
will
fail. It is my understanding that the only chance we have is if the batteries burn open some day in the future.
This is not the problem... you can not compare a spacecraft like AO-7 with Phase 3 satellites...
AO-40 would not work just from solar power and without batteries. The battery works as big capacitor for the transponders. In mean, the power budget would be positive, but during high peak on the transponder due to load, the transponder would drain current from the battery as the peak power would not be sufficient for the generated power from the solar cells. Without the battery, the transponder would be very unstable as the voltage breaks down. And even worse, the voltage break down would cause the IHU (onboard computer) to make a power down reset. So we could probably only have telemetry beacon, nothing else... During each eclipse pass, sometimes every orbit, the computer would also reset again and again. Since all the software must be reloaded from ground, this is a task we could not provide every day. But without computer, we would quickly loose orientation of the spacecraft and thus, the solar panelsl would quickly point away from the sun.. and that's is it.. Look at AO-10 to understand what I mean.. AO-40 was never designed to work without battery and this would also make totally no sense.. The problem was, that the Main Battery died so quickly in a totally catastrophic failure, which no one could have foreseen. Time for the command stations was too short to charge the Auxiliary Battery and do the switch over...
Command stations have tried to send command to the spacecraft since the battery failure, but the rate of these attempts decreased over the last couple of years. We at AMSAT-DL currently plan to make a new attempt using our 20m dish from Bochum. There we would have a lot of power and very good ears too.. However, I can not give an exact date when the will happen. Also it may need several weeks of attempts, since the attitude of AO-40 in regard to the sun is unknown. If we try at the wrong time, the solar cells may not generate any power due to bad sun angle..
We will indeed keep you all informed when we do our first try to recover AO-40 from Bochum...
73s Peter
BTW: Are there still people listening for AO-10?
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Auke de Jong, VE6PWN Sent: Saturday, March 01, 2008 7:53 PM To: AMSAT-BB Subject: [amsat-bb] recent AO-40 efforts?
I noticed that during the last period of documented efforts to recover
AO-40
4 years ago, there were promising results about hearing faint signals. By my interpretation of those old reports, they basically confirmed that the command receiver was working but could not get much else done with it.
Now
that it has been officially silent for several years, has anyone tried to send commands to it in order to disconnect the (shorted) battery banks via the relays onboard? Given the changing sun-angles on the arrays and the passage of time, as well as possible heating of certain onboard components due to the constant supply of solar power to the shorted batteries, could there be any possibility of (energizing) the battery-disconnect relays? I presume that they are in a fail-close arrangement, because if they were fail-open, they should have already done-so due to the shunted power
system.
Also, could the solar panels have fuses that have opened? could such
fuses
be re-settable?
I would be interested to hear what knowledge there exists about the
present
status of AO-40, especially what "google" couldn't fetch.
Auke de Jong VE6PWN DO33go Edmonton, AB
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb