FW: RE: starship-design: It's a bad, bad world out there

[David Levine <david@actionworld.com>]

Whoops - I had sent this to Kelly instead of everyone a few days ago.
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David Levine                                david@actionworld.com
Director of Development               http://www.actionworld.com/
ActionWorld, Inc.                                  (212) 387-8200
"The only reason for time is so that everything doesn't happen at once."

> ----------
> From: 	David Levine
> Sent: 	Wednesday, October 29, 1997 2:10 AM
> To: 	'KellySt@aol.com'
> Subject: 	RE: RE: starship-design: It's a bad, bad world out there
> 
> I dunno.  I assumed the following about the signal:
> 
> Transmitting frequency, f = 60 Hz, bandwidth = 1 Hz
> Power = 10 trillion watts
> Transmitting area = 23040000 m^2 (around 3000 miles by 3000 miles)
> System temperature = 300 kelvin
> 
> And using the equations at the link I posted previously, I make it
> such that an Arecibo-like radio telescope can detect this at around
> 0.2 light-years.  Also, this assumes that neither our nor their
> atmospheres absorb any of the energy.  If just theirs does, it assumes
> their Arecibo is in space.
> 
> If we double the power and the transmitting area, we are detectable at
> 1.6 light years.  If we QUADRUPLE BOTH, we are detectable at 12.8
> light years.  Here we are talking 40 terrawatts being broadcast
> contiguously over an area equal to nearly 2/3rds of the Earth's
> landmass.  And, again, this assumes the atmosphere plays no dampening
> or blocking role.
> 
> I hope you were kidding about 3000 m being a small telescope.
> Remember, this 3 kilometer telescope could not pick up TV signals at
> 1/100 of a light year.  To detect the signal at 10 light years
> requires a 95 kilometer telescope.
> 
> -----------------------------------------------------------------
> David Levine                                david@actionworld.com
> Director of Development               http://www.actionworld.com/
> ActionWorld, Inc.                                  (212) 387-8200
> "The only reason for time is so that everything doesn't happen at
> once."
> 
> 
> You have to remember, the whole continental power grid is syncronized
> and
> pulsing at 60 cycles per secound, with trillions of watts of power
> flowing
> through it.  Other EM sources lack the power, but are in frequencies
> that
> little else is in.  One quote I remember was that earth out shines the
> sun in
> certain EM bands.  Anyone interested in looking should have little
> difficulting seeing Earth em glow (and wouldn't limit themselves to a
> little
> 3,000 meter scope).
> 
> Kelly
> 
>