[amsat-bb] Re:Re: AO-40

["Stacey E. Mills" <semills@xxxxxxxxxxxx>]

Luc LeBlanc said:

>A0-40 is actually the only one satellite offering passes communication
>capabilities over a 15 minutes period.
>As stated by the commanding teams it could be too risky to go on 3axis 
>stab and
>deployed the solar pannel.
>I don't know how long ao-40 will survive in his present state? and how 
>long the
>batteries will be available
>with enough power to sustain the satellite.

There is no reason to believe that the main batteries won't last for many 
years.  The auxiliary batteries are also available and are currently being 
stored in a discharged state to prolong their lifetime.

>I guess it is probably possible to isolate the batteries banks from the
>charging units

It isn't.  For safety reasons, either the main or auxiliary batteries (or 
both) must be connected to the BCR's.  If you look at the PSU telemetry 
specs, you'll see that only three states are allowed, ie. main connected, 
aux. connected, or both connected.

>but i don't know if
>the charging units will be able to drive the whole power budget.

We have substantial excess capacity under most non-eclipse conditions.

>As a suggestion (If possible) the 3 axis/solar pannel should be done near the
>end of the planned end of life
>of AO-40 as a mean to extend the satellite life.
Extending the solar panels won't extend the satellite's life in any 
way.  Also, it's quite likely we won't know when the satellite is at the 
end of its life until it's already there.

>If ao-40 sustained internal physical dammages is it possible the solar 
>pannels
>realeased mechanism sustained
>dammages too?

It's possible, though the damage seems to be in the central core, not 
peripherally.  The panels all work fine in terms of power output and the 
release mechanism is very simple.  ..but I can't exclude the possibility 
that a piece of the omni end of the spacecraft could prevent one of the 
panels from opening properly.

>I don't also remember to have read anything explainig whats causes the 
>various
>TX loss and the antennas
>losses, Is it cables sectionning or direct physical dammages on the TX or
>antennas units?

We have no way of knowing exactly where the damages are.  Dead is dead when 
you're 60,000 km away.  We know that we lost all three omni antennas, a 
number of current/temperature sensors, the V-band Tx, and possibly a 
section of the omni-end sheet metal, after the "event".  It is likely that 
the C-band pre-amp which is located in the center section was lost at this 
time as well, though final testing has not been done on this.  Whether the 
X-band failure was due to the event or other causes is not clear.  It was 
not tested before the event, so we don't know.  The U-band Tx was dead 
immediately after launch.  The S1 Tx failed shortly after operation.  Most 
satellite equipment failures are manifest immediately after launch or 
shortly thereafter.  Let's hope that since the S2 Tx has functioned for 
several years, it is well past the "early failure" mode and will continue 
to function for a long time.

>I hope someone can give us all an updated after accident report giving a
>probable chain breaking events
>leading to the failures.

There's a good description of what we know about the event in the AMSAT-BB 
FAQ, under a title something like, "What happened to AO-40?"

>As an intensive care units language, is the patient condition is now 
>stable and
>can we expect any futur
>deteriorating conditions
>
>I know all of this can only be guessing but it will help us all to picture 
>out
>AO-40 present and futur state.

There is no reason to believe that AO-40 is any less (or more!) stable than 
that of any other satellite in space.  It could all die tomorrow, or still 
be functioning happily 10 years from now.  This is, after all, rocket science.


-- 
  ________________________________________________________________________
  Stacey E. Mills, W4SM    WWW:  http://www.keplerian.com
    Charlottesville, VA     PGP key: http://www.keplerian.com/key
  ________________________________________________________________________  

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