[amsat-bb] Re: geo stationary bird

[Mark Lockwood]

Another thing to remember is once attitude control is turned off, there is
also no way to keep the solar arrays pointed at the sun.  Once this happens
the on board computer will "Load Shed" and shut down everything not needed
to regain attitude control.  Switchable antennas would not be a help.

For satellites that are out of expendables (loss of too much redundancy, or
almost out of fuel).  They may be kept as a spare if they are usable at all,
or like on bird our company owns just held in the slot until a replacement
can be launched.  FCC and ITU require us to maintain the bird in the slot or
we loose the slot.  Once we stop doing maneuvers the birdwill start drifting
and become a hazard for other spacecraft.  The operator will once this
happens "SuperSync" it, kicking it up about 300 miles above the
geo-stationary or "Clark Belt", and permanently shutting off all
electronics.

In my experience most satellites have enough solar array power and battery
capacity to run through eclipse long past end of life due to fuel exhaustion
or some other catastrophic problem.  You can however count on the AMSAT
Payload being a lower priority than the revenue producing payloads, and will
be turned off first if there is a power problem.

I would support AMSAT investigating this and seeing if there is a
possibility of it becoming a project.  I would however like to see P3E
finished first.


Mark

On 11/5/07, Richard Limebear <Richard at g3rwl.demon.co.uk> wrote:
>
> Thanks for the replies
>
> >     Does anyone know if retired birds are switched ON or OFF once they
> >     get boosted into a retirement orbit ?  Could still be useful to us
> >     even from there.
>
> > For us it just means we need switchable antennas that can be swapped 15
> > years after launch.
>
> Accepted. We don't yet know what antenna assemblies will be permissible.
>
> > However, when the satellite enters eclipse, the TV etc transponders are
> > run from the batteries. I suspect that at this point, AMSAT would be
> > switched off or into some low power mode until the eclipse has passed.
> > The extra battery power needed for operation of AMSAT */_and_/*  the
> > commercial transponder  during eclipse would require a significant mass
> > increase of the on-board batteries.
>
> But thats the whole point of this exercise (piggy-backing inside a geo
> bird); there *is* extra mass availability due to the launch configuration.
>
> Good concept and has my full support as long as P3E doesn't become a
> victim of fund diversion.
>
> --
> 73
> Richard W L Limebear G3RWL
> g3rwl at amsat.org
> FOC # 1188
>
>               So many beautiful girls ... (sob) so little time
>
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-- 
Mark Lockwood
Prefect, Metropolitan Rocketry Association
TRA # 9863
NAR #86042
KK7CU