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Re: pt3 telemetry



on 1/5/01 6:31 AM, MCGWIER ROBERT at rwmcgwier@home.com wrote:

> As I stated, I believe we leaked propellant.   I believe this explains
> why the burn went long, why the regulator didn't regulate, why
> the electronic failures occurred, etc.

First of all, Robert, I have a problem with speculations.  We had plenty of
these when the bird first went silent.  I have an issue with the idea of a
propellant leak.  Here's why:

1.) You say the leak caused the burn to go long.  Why would it do that?  If
the leak is say in some of the plumbing inside one of the bays of AO-40,
what does a leak have to do with the length of the engine burn?

2.) I must admit that I am a novice on the propulsion system, but just
putting two and two together, if the leak was somewhere between the fuel
tanks and the regulator valves, wouldn't we still see the leak as occurring?
And if the leak is after the regulator valves, are those valves in a
position where said lead would cause possible damage to the craft?

3.) If the leak was after the regulator valves, I would expect a SHORTER
engine burn since some of the propellant slated for the engine would have
leaked away.

4.) Is the LIU or anything related to the valves/fuel system near the 2
meter transmitter?  I don't have my spacecraft drawings handy, but one would
expect the leak to have damaged components near by.  If the two meter TX is
not near the fuel system, then how did the fuel leak damage it?

5.) From what I have read from the control team, it appears that systems in
various areas of the spacecraft have been affected.  If indeed it was a
leak, I would think the majority of problems would be in one particular area
or at least concentrated there.  This does not appear to be the case.

6.) Why would a propellant leak cause the IHUs to crash?  I suppose that if
the leak caused a failure to the 2m TX then perhaps bad internal data fed to
the IHU caused it to crash.  That would seem like pretty poor software and I
think we would do a better job than that.  The IHUs weren't damaged by
whatever happened as far as we know since they are working fine now.  So why
did they crash?  If a leak did happen damaging the 2 meter TX then the
beacon would have gone off the air.  But the IHU should have stayed up and
eventually gone into command-assist, but it did not.

To me I think something else happened.  I still like the theory that it was
some sort of solar particle(s) that caused all this to happen.  Let me
speculate:

A proton event occurred that overloaded the systems on the spacecraft.  This
sort of overload/interference cause the IHUs to crash thereby taking the
spacecraft off line.  Additionally, with the IHU in an unknown, random state
various bogus commands could have been sent to different systems in the
craft.  Perhaps the magnets or the momentum wheels were turned on and that
increased the spin.  An electromagnetic event like this could damage sensors
in a random fashion or it could "uncalibrate" them.  It could damage RF
components, etc.

Of course, this could all be Sci-Fi and my idea totally flawed for one
reason or another.  And maybe my above conclusions about the propulsion
system are inaccurate as well.  They are just questions based on what I do
know (which isn't necessarily much!).

Lastly, I am bothered significantly by the two meter TX issue.  If it wasn't
damaged then what would have kept it from turning on when the reset command
was sent?  I can't think of anything in either the propellant or "proton"
scenarios that would have kept an undamaged two meter TX from coming back on
line.  With the problems seen with the UHF TX it is a shame if both low band
transmitters are off line.  Now it's really a shame that the 10 meter TX
wasn't finished!  Again, this is all speculation and things may be fine with
the 2 meter TX.  We will just have to wait and see.

73,

Jon
NA9D


-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)

Member:  ARRL, AMSAT, DXCC, NRA

http://www.qsl.net/ke9na

"A life lived in fear is a life half lived."

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