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Re: Right-sizing a sat






>From: "John Stephensen, KD6OZH" <kd6ozh@gte.net>
>I'm not sure what you are proposing. AO-40 was launched because AMSAT-DL
>recognized that AO-13 would reenter prematurely, identified a launch
>opportunity for a similar Molniya orbit satellite to replace it and built
>one to fit the available space. Since they had more space available they
>made the satellite larger so that they could increase downlink power and
>allow more people to use the satellite. The inclusion of extra bands hasn't
>made the satellite less reliable, but increased the possibility of a 
>working
>transponder in the event of failures.
>
>The major limitation for AMSAT is the cost of the launch. To launch
>satellites more often without increasing the budget means launching low
>earth orbit satellites instead of Molniya orbit satellites.
>
>73,
>
>John
>KD6OZH
>
>
>

then let me be clear.  I am proposing more satellites the size of Oscar 10 
and less the size of AO-40.

Lets start with "size".  I dont think that its a fair statement that AO-40 
is a AO-10 class bird that just grew.  That doesnt fit the literature from 
both the start of the project and all points in between; particularly as the 
project would reach one of its "end" points (ie when the ham magazines 
thought it was ready for launch).  The "size" required several new things, 
including the load bearing assembly that were not a part of earlier Oscars.  
PUt another way AO-10 sized paylods could have been launched on other 
Arianes...this one needed V.  (you might for reference look at the relative 
sizes of AO-40 and 10).

What does size have to do with it?  Your right what "seems" to have failed 
here is the propulsion system.  Guess why the propulsion system is the size 
that it is in terms of energy?  The mass of the spacecraft.  While previous 
vehicles have had less then great engine performance the requirements of the 
engine were based on teh mass.  Less mass and one can get by with less fuel 
etc.

Also we dont know that the only failure in the system will be what has 
failed right now.  While problems with the engine could be the problems with 
the antennas there could also be other problems on board...and even had the 
propulsion system not failed you dont know what other failures are "there" 
or why.  I think that certian transmitters were dead on orbit long before 
the "mishap".

But in the end what it all boils down to is resources.  I cant imagine that 
you believe that we could have built only 1 AO-10 class veihcle for the time 
and resources that have gone into this bird?  AND there have been other 
launch oppurtunties which have simply been missed because no payload exist.  
OK want a specific orbit with a specific payload and not willing to pay then 
chances come along rare in life and this was a gold mine.  But if you are 
willing to be ready when any oppurtunity strikes then one has more chances.

But I bet you a dime to donuts that there are two realities in amateur 
satellites futures.  The first is that AO-40 isnt going to come anywhere 
near 100% of its sold capabilities.  The second is that we would have never 
had the resources to do another AO-40 again no matter what had occurred 
here--and especially now.

None of this is being critical of the command team but it does suggest that 
some discussion should be had about where the future lies.

Robert Oler WB5MZO Houston TX

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