Re: [amsat-bb] Longevity-sat proposal

[Emily Clarke <emily@xxxxxxxxxxxxxxx>]

Hi Jim,

I didn't, but I probably should go back and make a chart.  Perhaps this 
weekend.

73,

Emily



At 08:06 PM 10/30/2003 -0700, Jim White wrote:
>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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>
>
>----
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