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

In a message dated 10/29/97 5:00:27 AM, you wrote:

>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

Hum depressing numbers on the transmit range.

No I wasn't kiding that I though a 3 kilometrer antena was small.  A few sats
spaced around lunar orbit would make a nice 3 light secound antenna.  If we
were really interested in looking that wouldn't be an outragious expense.