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Re: Bravo to the command team!



----- Original Message -----
From: Steve Diggs, W4EPI <w4epi@mediaone.net>
To: Ken Ernandes <n2wwd@mindspring.com>
Sent: Tuesday, January 09, 2001 9:03 AM
Subject: RE: [amsat-bb] Bravo to the command team!


> Hi Ken,
>
> Thanks for the excellent analysis. I understand the situation a bit better
> now.
>
> 1. If I understand correctly, you are suggesting that the leak is directly
> out of the 400N engine bell, in the same direction as we would get if
> hypergolic ignition was underway.

That's not proven, but there is reasonable evidence that may be the case.


> 2. #1 seems to suggest that the problem is that one of the two main
valves,
> either on MMH or N204 didn't close completely.

Again there is reasonable evidence to support that.


> 3. If #2 is correct, then perhaps what we are seeing in the way of
> electronics damage isn't related to a leakage at all, as the leak is
> completely external to the s/c.

I'm not sure we can draw that conclusion.  There is strong evidence of
external propellant leakage in a constant direction that suggests [at least]
the dominant component may be coming out of the 400N nozzle.


> 4. I am also curious about the current thinking about whether we will ever
> get to use the 400N engine again. If all we have here is a leaky valve,
then
> we might be better off just to complete the 400N firings and be done with
> all the mass and danger that the main propellants represent.

That's out of my area.  I'm certain that's a very difficult decision that I
think needs further assessment of the health and status of the spacecraft.


> 5. I wonder if we are getting any telemetry regarding the MMH and N2O4
tank
> pressure values.
>
> Well, that's about enough supposition for now. I would appreciate any
> comments you have on my ideas.

See in-line comments above.


> Regards,
> Steve Diggs, W4EPI
>
> PS: "8th order gepotential model" ??

That's a *very* complicated model of the Earth's gravity field that computes
the effects independently of
(A) 8 Latitude "Zonal" terms -- slice the Earth into 8 latitude zones.
(B) 8 Longitude "Sectoral" terms -- cut the Earth (like an orange) into 8
longitude sections.
(C) A combined grid of Longitude and Latitude terms call "Tesserals."

73, Ken N2WWD




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