A while back someone posted that Arecibo would make a nifty
antisatellite weapon. I kind of blinked at this, but decided to look
into it...
large transmitter in a relatively narrow beam, the interplanetary
radar beam on this baby measures in the tens of terawatts. Now I
don't know how well a satellite would absorb the energies it puts out,
but I can't imagine that the results would be pretty.
Kinda nixes all those science fiction stories about orbital colonies
breaking off to form their own independent nations, eh?
Not really. Arecibo cannot transmit a truely parallel
beam. It's not a laser. Though it may have a long
range, it would still be limited by distances much
beyond GeoSync, say at L5 or furthur,,,
Not really. Arecibo cannot transmit a truely parallel
beam. It's not a laser. Though it may have a long
range, it would still be limited by distances much
beyond GeoSync, say at L5 or furthur,,,
Oh, I understand that, it's a flashlight, not a laser beam, but still, a flashlight whose surface puts out as much energy per meter as the surface of the sun (albeit in different frequencies) is still going to command a lot of respect.
beam. It's not a laser. Though it may have a long
range, it would still be limited by distances much
beyond GeoSync, say at L5 or furthur,,, The other part of it which didn't quite sound right to me was the talk of terawatts. Correct me if I'm wrong, but isn't terawatts a unit of measure more appropriate to discussions of global energy usage? I have no doubt that Arecibo could interfere with the function of a communication satellite, but as far as damaging it, I'm skeptical.
Mike Combs
Here's the page I got that figure from:
Scroll down a bit:
"Dave Hersherger adds: "Apparently, the highest ERP is produced by the
interplanetary radar transmitter at Arecibo, Puerto Rico. Continental
built this transmitter too - it's a 1 megawatt (CW, not pulsed) S band
(2300 MHz) source. It's two klystrons, at 500 kilowatts apiece,
combined for a megawatt CW.
"The dish at Arecibo (seen in the movie "Contact") has a gain of 74 dB
(!) at S-band. And with the interplanetary radar running, the ERP is
23.6 - not megawatts - not gigawatts - but TERAWATTS (i.e. 23.6E+12
watts or 23,600,000,000,000 watts). I have been told that this is
equivalent to the energy flux of a small star.
"When the Arecibo transmitter was being built, it was called the "E.T.
Phone Home" transmitter. When that thing was fired up it glitched the
power line so bad that every PC that wasn't on a UPS rebooted, and the
phones all started ringing.""
> The other part of it which didn't quite sound right to me was the talk of
> terawatts. Correct me if I'm wrong, but isn't terawatts a unit of measure
> more appropriate to discussions of global energy usage?
ERP refers to "Effective Radiated Power"
http://encyclopedia.laborlawtalk.com/Effective_radiated_power
"...if the antenna is directional, the ERP figure is usually the
maximum in any one direction, rather than the average."
A one mega-watt sec. transmission compressed into a
nanosec burst is an instantaneous power rate of one
tera-watt. Sounds impressive, but, really,for just one
nanosec? My 1500 watt micro wave oven takes 5 minutes
to really heat up a cup of coffee. 1500 times 300 sec
= 450,000watt-sec. about half the power rate of
Arecibo. My guess is, if you ran Arecibo for 2.5
minutes, continous, you could make a cup of java hot
enough to drink,,,
Do an experiment. Take a CD-rom (a blank one, or one you want to destroy) and put it in your microwave, for one second.
nanosec burst is an instantaneous power rate of one
tera-watt. Sounds impressive, but, really,for just one
nanosec? My 1500 watt micro wave oven takes 5 minutes
to really heat up a cup of coffee. 1500 times 300 sec
= 450,000watt-sec. about half the power rate of
Arecibo. My guess is, if you ran Arecibo for 2.5
minutes, continous, you could make a cup of java hot
enough to drink,,,
Don't confuse the effect of a 1500 watt micro wave
transmission on a metallic surface with the total
amount of energy involved. A cd will reflect the micro
wave back to the transmitter, which introduces
interference that disapates energy in a useless spray
of heat and a buildup of electrical discharges on the
CDs metalic structures. A very impressive display of
sparks, but not something an open transmitter like
Arecibo would produce. It is, after all, not a
resonance box, like the chamber of a micro wave oven.
I'd never put a cd in my micro wave, as it would
likely ruin the micro wave generator, which used to be
a klystron tube, but has probably been replaced by
something solid state these days,,,
> I'd never put a cd in my micro wave, as it would
> likely ruin the micro wave generator, which used to be
> a klystron tube, but has probably been replaced by
> something solid state these days,,,
A ten-second google search (+CD +microwave) resulted in the following link:
http://www.prairienet.org/~tatwell/cd_burning.html
I've done it many times... whenever I need to throw away a CD that has
information on it.
What has a sense of adventure to do with it? and why
do you think my email address is Dead_naked_drummer???
On 8/30/05, GARY ANSORGE dead_naked_drummer@... wrote: What has a sense of adventure to do with it? and why
do you think my email address is Dead_naked_drummer???
Here's the header from the emails I get from you:
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The "From" field is what Gmail is reading to get your address.
Actually, I don't think the original quote was on compressing Arecibo
from 1 MW-sec to 1 MW-microsec (which is all you'd need for a TW, not a
nanosecond). I don't think you normally compress radio waves to
microsecond pulses for any real purpose. Rather it was referring to the
effective number of dB's amplification caused by the antenna focusing:
the 1 MW from Arecibo focused produces a power in the focus direction
equivalent to what a uniform transmitter would emit if it were going at
several TW.
Oh!!!
> On 8/30/05, GARY ANSORGE
> >
> > What has a sense of adventure to do with it? and
> why
> > do you think my email address is
> Dead_naked_drummer???
>
> Here's the header from the emails I get from you:
>
> X-Gmail-Received:
> 9d5c10bad528f25e64f33555468acfcbb24d53ef
> Received: by 10.36.23.17 http://10.36.23.17> with
> SMTP id 17cs22673nzw;
> Tue, 30 Aug 2005 13:56:49 -0700 (PDT)
> Received: by 10.36.33.9 http://10.36.33.9> with
> SMTP id g9mr2117275nzg;
> Tue, 30 Aug 2005 13:56:49 -0700 (PDT)
> Return-Path:
>
gmail.com@...
> http://66.94.237.40>])
> by mx.gmail.com http://mx.gmail.com> with
> SMTP id
> r15si1033622nza.2005.08.30.13.56.49;
> Tue, 30 Aug 2005 13:56:49 -0700 (PDT)
> Received-SPF: pass (gmail.com http://gmail.com>:
> domain of
>
sentto-2400814-6710-1125435386-vaxalon=gmail.com@...
> designates 66.94.237.40 http://66.94.237.40> as
> permitted sender)
> DomainKey-Status: good
> Comment: DomainKeys? See
> DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
> s=lima;
> d=yahoogroups.com http://yahoogroups.com>;
>
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Ah, thank you Arthur, for the clarification. I'd
completly forgot about the focusing aspect. Ah well,
sometimes the greatest minds go off half
cocked.Unfortunately, half cocked usually also means
hair triggered,,,