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

["L. Parker" <lparker@cacaphony.net>]

On Thursday, October 30, 1997 9:55 AM, David Levine 
[SMTP:david@actionworld.com] wrote:
> Whoops - I had sent this to Kelly instead of everyone a few days ago.
> -----------------------------------------------------------------
> 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

I would only disagree with your assumptions for power. That is the actual 
power consumption, not what is broadcast by leakage.

> >
> > 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.

Ours probably does absorb some, but what happens when we move off planet 
and start building solar power stations and beaming the power around with 
microwaves? I didn't look at the link you posted, would you either repost 
it or plug in the figures for say, a ten megawatt maser?

I wouldn't want to make assumptions about their telescope. Using improved 
electronics and signal processing we ourselves have managed to improve the 
sensitivity of all our sensors by several orders of magnitude.

> >
> > 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.

Well, even if we give them the benefit of the doubt and assume their 
detector sensitivity is ten times better than ours, they still shouldn't be 
able to detect leakage. Beamed signals might just be within possibility.

> >
> > 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.
> >

I don't find that unreasonable, the astronomy community is already 
discussing radia telescopes in orbit larger than that. Of course they are 
talking about very long baseline arrays, but it shouldn't make any 
difference.

Lee