Re: [amsat-bb] an amateur satellite for $295

["Robert Bruninga" <bruninga@xxxxxxxx>]

>>> Robert McGwier <rwmcgwier@comcast.net> 07/21/06 9:33 AM >>>
>Baaaaa.   Did you look at the videos?   They let the "your items" 
>float free INSIDE the spacecraft in Genesis I.    It would not do much 
>good to have our golf ball inside a Faraday cage...

Ah, yes, that is why my  tongue-in-cheek proposal #1 was accoustic
coupling to the outside.  ANd proposal #2 added an additional
30 dB on the uplink to get through leakage paths into the
bubble from the ground..  I assume their aluminized coating is 
not designed for RF tightness, but to provide a good thermal
isolatoin from the space environment.  Hence, 30 dB leakage
paths would not be unreasonable.  Using a KW on the ground
could get in...  

ANyway, it was not a serious proposal at all.  But just the
only engineering approach I could think of to get around the
limitations imposed....  but if they are serious about no
"power" then nothing can work....  Bob


Robert Bruninga wrote:
> Only possible COMMS method from inside to outside I can see is
> Accoustic, to modulate the aluminized bubble skin, and then
> Laser reflection from the ground to recover that on the ground <GRIN>...  
>
> Or, from outside-in, use a wrap-around LCD display on the tiny package
> that can display packet messages sent from the ground with high-
> power transmitters.  The messages are seen on the on-board 
> camera that views the items and then to the website.... Bob
>
>   
>>>> "Tom Clark, K3IO" <K3IO@verizon.net> 07/20/06 5:44 PM >>>
>>>>         
> It appears that the keep the items contained and flying loose within the
> inflatable module(see the graphic at
> http://www.bigelowaerospace.com/fly_stuff/items/examples.php), so you
> must be prepared to occasionally contact somebody else's item and the
> balloon's walls. Also, as Pieter noted, it's not clear how much solar
> energy leaks thru the VECTRAN (http://www.vectranfiber.com/)skin if you
> want to try some solar mini-panels for power.
>
> I also note that Vectran has a dielectric constant = 3.3, so when you
> design your antennas, you need to take into account that you will be
> executing a random walk inside a "balloon" which has a velocity factor
> of 1/sqrt(3.3)=0.55 and an aluminized skin.
>
> Have fun !! -- 73, Tom
>
>   


-- 
AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
"An expert is a man who has made all the mistakes which can be
made in a very narrow field."  Niels Bohr
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