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Re: SuitSat-1 Final Experiment Proposal



On Feb 27, 2006, at 1:35 PM, Pat Kilroy wrote:

> ASSUMPTION 1
> I understand SuitSat-1 power was derived from three
> primary batteries at 28 VDC connected in parallel
> and through a regulator or DC-DC converter down
> to around 12 VDC and lower for the xmtr and
> supporting electronics.
>
Suitsat used a DC-DC converter that maintained the transmitter power  
source at 12VDC until the batteries dropped below 12VDC.
There was not a gradual decrease of transmitter power until the very  
last. I anticipate the decrease became very rapid after 18V on the  
batteries.
> ASSUMPTION 2
> Electric current in primary batteries are derived
> from a chemical process.  Chemical processes run
> at a reaction rate which is often estimated by
> engineers to double with every 10 deg C increase
> in temperature, or conversely, that is reduced to
> half with every 10 deg C decrease in ambient
> temperature.
>

> ASSUMPTION 3
> The batteries were running pretty cold during the
> experiment, perhaps even assisting in extending
> the life of the experiment -- if not at the cost
> of reduced efficiency but I am starting to digress
> here due to the several other flying assumptions.

All telemetry received indicates a very benign temperature of around  
13DegC (55   DegF) inside the suit. There is no indication that the  
batteries were degraded due to low temperatures. All indications are  
to the contrary. The batteries delivered more power than we expected  
based on measurements before launch.


>
> PROPOSAL
> Why not continue to monitor for SuitSat-1 emissions
> through the expected re-entry (or entry? or de-
> orbit?) dates?
>
> REASONING
> The temperature of the suit and its contents will
> rise substantially leading up to its de-orbit time.
> There might be a period of time when the batteries
> warm up enough and "wake up" for a final period of
> discharge enough to allow SuitSat-1 to come to
> life at or a little before system meltdown.

It never hurts to listen.
>
> Seconds, minutes or hours of warm life under these
> conditions?  Who knows!  But, ...

I wouldn't want to get false hopes going. I see no reason to expect a  
revival from the dead.
>
> Will any of us be patiently listening for its
> truly "final words"?
>
> Just a thought to share.
>
> Cheers,
>
> Pat Kilroy, N8PK
> AMSAT Area Coordinator
> Maryland-DC Area
> http://www.patkilroy.com/amsat-dc/
>
> =================================================================
> Patrick L. Kilroy                                             WK
> Integration & Test (I&T) Manager    301-286-1984 Voice
> NASA Goddard Space Flight Center    301-286-1673 Fax
> Building 5, Mail Code 568           Patrick.L.Kilroy@nasa.gov
> Greenbelt, Maryland  20771          http://patkilroy.com/bpp/
> =================================================================
>
>       "A problem well stated is a problem half solved."
>                   -Charles F. Kettering
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Louis McFadin
w5did@mac.com
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