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Re: Longevity-sat proposal



Emily,

I found your failure data quite interesting. You have obviously spend more 
than a bit of time digging.  Did you perhaps keep notes on which satellites 
fell into which category, and possibly whether they failed prematurely?  As 
one involved in the business of building these that would be a great 
interest to me.

Jim
jim@coloradosatellite.com



> From what I can gather out of AMSAT records, the reasons satellites go SK 
> are varied but batteries lead the way.
>  8 De-Orbits
>14 Battery failures
>  7 Computer failures
>  5 Transponder or receiver failure
>  1 Temperature failure
>  1 Radiation related failure
>  8 For unknown reasons
>  3 Other reasons
>
>>3.  Only provide the simplest control.  Transponder On and OFF. That's it.
>
>That's pretty simple.  However once you provide controls for one action, 
>adding additional controls is relatively easy.
>
>>4.  Linear transponder with analog receiver and transmitter.
>>Would need to be carefully designed so that the frequency was stable as
>>the voltage went up and down.
>
>See my comments in #1
>
>>5.  Omni antennas.  Assume tumbling and prepare for that in
>>advance.  Design it so if it tumbles it's still okay.
>
>Good idea but this would mean more tx power.  If the satellite is tumbling 
>it might run into a situation where the antenna gets partially or 
>completely shadowed by the satellite body.  Spin stabilization would be 
>much better.
>
>>6.  Elliptical orbit.  The idea being without the CPU maybe it
>>could take a decent amount of radiation without melting down.
>>Simple stations could work it while low, and the big guns could
>>work it while high.
>
>Probably depends on how high you are talking about.  With low gain omni 
>antennas it probably can't get very high.  What kind of inclination would 
>you propose?
>
>>7.  Solar panels on all the sides.  So, that there's power to the
>>satellite most of the time.
>
>I think all LEOs have panels on all sides (and I think presently so does 
>AO-40).
>
>>I was just thinking of AO7 and how it works with no cpu
>>and no batteries, and well, why not make something that's
>>designed to work like this from the start?  The idea being that
>>if we accept limitations, maybe it could last a really long time.
>>
>>Has this ever been considered?  I'm not a satellite guru at all --
>>so maybe I'm not aware of the 'horrible flaw' with this idea.
>
>No flaws, just challenges :-)
>
>- Emily
>
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