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Telescope Cluster For SETI
ContinuousPark writes: "MSNBC is reporting that radioAstronomers showed today the Rapid Prototype Array, which consists of seven 12-foot off-the-shelf satellite dishes, set up at the Russell Reservation near Lafayette, CA. This experiment, in which computer software will control the drive systems of the dishes and process all gathered information, is going to tell astronomers how to build much bigger radio telescope arrays such as the 1-hectare telescope and the Square Kilometer Array; the SKA would be 10 to 100 more sensitive than the Arecibo radiotelescope. Check out the SETI Institute press release and photos. "
Because it is searching for information and the truth about life. Some people seem to think that God wants humans to remain idiots. If this AC were alive 500 years ago, he'd have been petitioning to get Galileo burned at the stake.
Make em cheap so any school/enthusiast can put one in their back yard/garden.
Still, it's difficult to see how they'll get quality results from cheap kit.
Deleted
But, then again, I am a Christian and I DON'T agree with you that this "flies in the face" of our beliefs, so maybe you should just put out that decree for the people of your Christian sect. Unless the majority of the people in your sect disagree with you, then you're screwed -- unless you're Catholic, then you just need the Pope to dictate it and everyone must follow.
I know I should resist the tempation of arguing with someone who falls for a not-so-subtle troll (but who am I to know? you probably like it!) but I have to call your attention to the fact that most Catholics (Roman, Orthodox, Coptic etc) do not follow blindly the guidance of the Pontiff of Rome. Some, as think I made clear, do not even consider His Holiness to be the leader of the Church.
I keeping with the trollish nature ogf this thread, I should finish be stating that when you mean youe a "Christian", what you really mean is that you're a Protestant, i.e., a heretic, pagan-descendant, fool who follows theologically illiterate slysters selling religious snake oil and believes blindly in the words of the prophets, written in the Book, forfeiting any interpretation and historical analysis of its narrative.
Information wants to be beer, or something like that.
... considering what had just happened to the Rand Wilson telescope a couple of days ago.
Actually, the Arecibo radio dish is 305 meters. In any event, while Arecibo is certainly an important radio dish, it also has problems. The biggest being the fact that Arecibo cannot track things across the sky. It only has a limited time window each day to collect data from a certain spot. This is obviously a problem, as it's not possible to build radio dishes of this size and allow them to move.
This is where Very Large Array's come in (which is what all of these dishes will create). The great thing about VLA's is that they can, with the use of computers, collect data over a very large area. Take for example the VLA in Siccoro, New Mexico. It has 27 dishes, each 85 meters in diameter shaped essentially like this:
OO
\/
OO
\/
O
|
O
|
O
(this is obviously a scaled-down version..but you get the idea)
And each of these "arms" is about 12 miles long. It is then possible to take all of the data collected from each of the dishes and spit out information. In other words, it acts as one dish, miles and miles across that is able to track things as they "move" across the sky.
~Steve
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"<r-xr-xr-x> Just try to edit me" -- www.ircnews.com
The idea of creating VLA's (very large array's) is nothing new. Even the idea of setting up a VLA that covers the whole earth has been around for a while.
However, there is one HUGE problem: TIME.
There are two problems with time. The first is, that, while I live in Florida (EST), it is not the same time [technically] for me as it is for someone in Maine (also EST) seeing as how we are at different latitude. This problem could probably be easily overcome, however the second problem, which is not as easy, is that clocks do not keep exact time. If I were to set to clocks to the exact same time (which would be hard in itself), before long, they would have varied times. Without everyone having the exact same time, correctly analyzing the data collected by the dishes will be near impossible. And so, we have a problem: how often would we all have to reset our clocks to put them all in sync.
If someone can figure this out, we should have no problems using the whole globe as one big telescope. Good luck
~Steve
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"<r-xr-xr-x> Just try to edit me" -- www.ircnews.com
ack..radio dishes..NOT telescopes
~Steve
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"<r-xr-xr-x> Just try to edit me" -- www.ircnews.com
It seems clear to me that they're trying to lay down the groundwork so they can incorporate a tremendously huge network of cheap backyard dishes with cheap controllers. This is great. They've had it on their plate for a long while now.
The problem here is that one plan I really liked was once to incorporate dishes from all over the place (but all in the same sky) and really use individual contributors. But they will not have a demo of the small and tight system before 2005. But given all the small dishes out there, by 2005, the number of large backyard dishes will be greatly diminished. Now adays you can pick one up as junk for a couple hundred bucks.
ok, where did that article come from?! To me, it's obviously a joke. I couldn't find anything on the page showing that it would be a conspiracy theory type magazine though. Family Digest? Huh? What up with this?
Hmm, I thought I did mention in the article that there were other applications, in the lede as well as in the body of the story:
;-) of stories about applications of radio astronomy, although I concede that SETI accounts for most of the stories, being the sexiest application (as well as the most speculative, the most redolent of vaporware).
"During a presentation earlier this month at NASA's Ames Research Center, Tarter emphasized the wider applications of the 1HT and the Square Kilometer Array. She said a telescope array with an area equivalent to a square kilometer could:
Identify Jupiter-size planets beyond our solar system, as far away as 30 light-years from Earth.
Map the winds and jets created during star formation, and analyze the chemistry of the dusty disks that serve as the birthplaces of stars and planets.
Serve as the model for a next-generation Deep Space Network that would communicate with robotic explorers.
Produce radar images of near-Earth asteroids that are 10 times better than currently possible.
Expand the SETI search to up to a million star systems.
She made it clear that she hoped the technology would benefit all of radio astronomy, and indicated that DSN was receptive to the idea (although they would probably develop their own array).
We have published a wide "array"
To wit:
http://www.msnbc.com/news/135107.asp
http://www.msnbc.com/news/154126.asp
http://www.msnbc.com/news/106245.asp
http://www.msnbc.com/news/392946.asp
http://www.msnbc.com/news/135324.asp
Please feel free to send along other suggestions for radio astronomy stories to alan.boyle@msnbc.com....
All the best, Alan Boyle (aka alanb0)
SETI, and especially SETI@Home, makes me wonder what a hyper-intelligent extraterrestrial would do , after stumbling upon a planet with an open port to it's global computing network.
At any given moment in history, it only took a few years for our own primitive technology to crack our own primitive security. It would probably take milliseconds for an intelligent race that's mere decades ahead of us, much less centuries or millenia.
While we discuss DDOS attacks that exploit droves of 'script kiddies' who've put insecure PC's on the net, and traffic in once-secret encryption keys for DVD's, we're happily putting our internet into cosmic promiscuous mode.
Of course, there's no such thing as a packet that could get through all of the workload-distributing, Fourier-munging SETI@Home network and do any real damage. Not even hyper-intelligent extraterrestrials could make such a thing, and even if they could, they wouldn't use it to hurt some poor, innocent planet.
But for killing cosmic roaches, that's another story.
Adam
Click Here for WebHosting
That's a big shelf...
It seems (just from reading web pages) that highly accurate positioning information and noise control is critical to small arrays of dishes, and that plus atomic-clock-level time accuracy, normally keyed from satellites like Project Argus, are some limiting factors for large interferometers.
If you had two or more ccd cameras on small (3"-8" dia. telescopes) and a single pc though, I'm curious about whether you could build a working optical interferometer or phased array (it might work until a gnat walking by jiggled one by 1/2 wavelength..). Mostly I've heard about gain, sensitivity, and patch size for radio astronomy but if optical is so great what is the simplest working thing you can make with this? Could you do interferometry on this in realtime on a Pentium III (phased array math sounds a lot harder) and resynchronize very often so you could move the set around?
I'm curious how much sheer processing power (such as it is on consumer electronics..) can make something interesting (multipixel imaging hopefully) with minimal input. Can this be demonstrated in optics with pinhole cameras, or in radio range with fresnel lenses or just (doh) jumbled lengths of wire? I'm thinking of interesting uses within the solar system or on Earth.
Last question, if you had a GPS
cf. "Phasing Several Smaller Antennas"
http://www.setileague.org/askdr/interfer.htm
World's tiniest fiber optic spectrometer (!)
http://www.coseti.org/oceanop1.htm
Columbus Optical SETI (a 10" telescope!)
http://www.coseti.org/introcoseti.htm
"..it might not be ridiculous to suggest that eliciting the help of thousands of enthusiastic amateur astronomers would considerable aid.."
http://www.coseti.org/radobs31.htm
http://www.coseti.org/tecspmap.htm (tech index)
..if you had a GPS receiver attached to your computer and you kept cpu load (& temperature) pretty stable, could you do away with the atomic clock in some cases? (within 1 to 10 milliseconds with NTP and luck..)
n dex.htm
cf: Network Time Protocol
http://www.eecis.udel.edu/~ntp/ntp_spool/html/i
-shudder-
My SETI is processing away as fast as it can, and we are still only processing data recorded in Febuary!
Whatever are we going to do with more data?
Do we need to record faster and more than we can process?
Golly Gosh.
PS: Whee... just completed 150 work units..
-chuckle-
Closer to home is the meteor crater in Arizona. Its face is about 1.5 million square meters, or about 20x bigger than Aricebo. It would give about a 400-fold signal increase, but it is probably harder to manufacture and obscures a natural wonder.
To-do List: Receive telemarketing call during a tornado warning. Check.
Could you explain *how* SETI research "flies in the face of God?"
Optical SETI isn't a new idea though. Townes and Schwartz's first proposed optical SETI in 1961, a year after the invention of the laser. After many years of lobbying be a few brave scientists, optical SETI experiments are now running (or being built) at a handful of institutions.
I'll explain a bit about optical SETI below, but let me also point you to a few good resources. The SETI group at Harvard (of which I am a member) maintains www.oseti.org which has a couple articles on optical SETI: a technical paper that gives the full arguments for optical SETI, and another technical paper which details our current running experiment and our future all-sky survey.
Here's why optical SETI is a good idea (much of which lythari cites): A high-intensity pulsed laser, teamed with a moderate sized transmitting telescope, forms an efficient interstellar beacon. To a distant observer in the direction of its slender beam, such a laser transmitter, built with ``Earth 2000'' technology only, would appear (during its brief pulse) a thousand times brighter than our sun in broadband visible light; even at ranges of 1000 light years a single nanosecond laser pulse would deliver roughly a thousand photons to a 10-meter receiving telescope.
There are several reasons why optical SETI is at least as good an idea as radio SETI. First, transmitted beams from optical telescopes are far more slender than their radio counterparts owing to the high gain of optical telescopes (150 dB for the Keck Telescope versus 70 dB for Arecibo). Dispersion, which spectrally broadens radio pulses, is completely negligible at optical frequencies. The capability of radio transmitters has reached a stable maturity, while the power of optical lasers has shown an annual Moore's law doubling extending over the past 30 years. And finally, the computational power and sophistication characteristic of the sensitive microwave searches today is unnecessary for optical SETI. Detection can be quite simple -- a pair of fast, broadband photon counting detectors in coincidence.
We have built a photometer to search for such unresolved pulses, and are using it in a piggyback targeted search of some 3000 nearby solar-type stars. The photometer receives about 1/3 of the light focused by the 1.5-meter optical reflector, otherwise unused by the primary experiment (a stellar radial-velocity survey). A beamsplitter followed by a pair of fast hybrid avalanche detectors is triggered in coincidence to record the time and intensity profile of large pulses.
We're also working on an all-sky search for pulsed optical SETI beacons at Agassiz station in Harvard, Massachusetts. We envision a 2 meter f/1 parabolic "light bucket" (1 arcminute resolution) focused onto a multipixel camera consisting of eight 64-pixel photomultiplier tubes (with pixels measuring 4 arcminutes on a side) in two matched focal planes. It will observe a two degree by half degree patch of the sky in transit mode, thereby covering the Northern sky in 150 clear nights. Fast custom IC electronics will monitor corresponding pixels for coincident optical pulses of nanosecond timescale, triggering storage of a detailed digitized waveform of the light flash.
The sender would know to point it in our direction because They (with a captical "T") would have surveyed their corner of the galaxy, and found planets that potentially harbor life. They could do this is to first discovering planets by astrometry or radial-velocity techniques, and then looking for absorption lines such as ozone in the planet's spectrum. In fact, NASA will employ this very techinque in its Terrestrial Planet Finder mission. In optical SETI (where the beams are much more slender than in radio SETI), one expects to discover intentional beacons, rather than accidentally intercepting interstellar communication.
Suppose a god exists. Wouldn't this god want us to *use* the intelligence it endowed us with to explore and discover the natural universe?
The bible may be very clear creation, but so are many other religious documents on the subject. How do you know which one (if any) to believe?
I'm not sure what you meant by, "Moreover, are these the people that you want to have sending it [the message to god]?" Perhaps you could expand.
Stop complaining; your hard-earned dolars aren't going to SETI. Congress terminated funding for SETI 1992. They're conducting science for the sake of science, and it isn't costing you anything.
There is one problem with searching for alien laser beacons using this kind of a system: What if you actually find one?
If there is one thing I know about the scientific community, it's that they always try to find a natural reason for any phenomenon.
So you find something that looks like a laser and is pulsing. "Aliens!" you cry, but the scientists you work with then concoct some weird theory using "dark matter" and "exotic particles" to explain away you're discovery as false. And they get the credit, because they have the PhD's, right?
Scientists are still people, and some will always twist facts to get the result they want.
PS - The previous was only my opinion. I am not trying to troll or start a flamewar. But I think my point has merit, and I want to share it with the rest of the Slashdot Community.
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"You spilled my egg... I needed that egg."
Since you brought up seti-at-home, what's kind of results have they been getting? Their own list of top hits is here:
m l
http://setiathome.berkeley.edu/stats/gaussians.ht
But what does that mean? How do these compare with the famous "Wow!" signal? I realize that they could just be an unfortunately sweep over a telco or broadcast source... that's why they stopped listing the top powers.
... the network of satellite dishes-turned-radio telescopes that Charlie Sheen created in The Arrival. Hmmm... it has been getting warmer in recent years. Just a coincidence I'm sure.
"There is no shot you can take that I cannot simply deny." - Ertai, wizard goalie
Does this remind anyone else of 'Imperial Earth' by Arthur C. Clarke where there is a wide area radar array searching for signs of extra-terristral intelligence.
Unfortently, the search was unsuccessfully, only because it was looking in the wrong length of the radio spectrum (IIRC in the thousands of metres range)
Richy C.
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Don't be an idiot. First off, you can't negotiate opinions -- someone's opinion, idiotic as it may *seem* to be, is just that. If I want to ban animal testing, but I don't want to ban astronomy, that's my opinion and that's the end of it.
Second, YOU'RE saying "Settle down"? Where do you get animal research from on this and how do you assume this guy wants a ban on animal research??? He mentioned torturing and burning people at the stake to *jokingly* point out how ridiculous the original post was. Unless you actually BELIEVE that we should selectively ban scientific research because of one *small* group's beliefs -- like it or not, we Christians are the minority in this world. Or maybe you could say, "OK, if you are a Christian scientist, you CANNOT do any SETI research because it flies in the face of our beliefs; but if you are one of the many atheist, agnostic, Buddhist, etc. scientists, then go right ahead and do it."
But, then again, I am a Christian and I DON'T agree with you that this "flies in the face" of our beliefs, so maybe you should just put out that decree for the people of your Christian sect. Unless the majority of the people in your sect disagree with you, then you're screwed -- unless you're Catholic, then you just need the Pope to dictate it and everyone must follow.
Back on topic, I personally don't think any scientific research should be "banned". If it poses a serious potential threat to any life, it should be handled carefully and sparingly. If it has serious potential benefits for life, then it should be prioritized higher than other research. Anything else should be somewhere in-between. SETI falls possibly into all of these areas because a success would be such a major event in human history -- potentially positive and negative. So IMO, we should proceed with SETI research very carefully, but it should be a medium to high priority.
Hmmmm... but why do you assume that They won't decide that announcing their presence to us is sorta like driving into East LA and loudly asking, "Hey, can anyone here change a hundred?"
After all, we have broadcast our nasty habits on the evening news for quite a few decades now, so all the nearby Thems should have us figured out...
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Politics is about making compromises. Religion isn't. --Michael Horton
The link goes to the Weekly World News site. For those who may not be familiar, Weekly World News is kind of like conspiricy theory for rednecks. The whole magazine is devoted to printing stories so blatently fabricated that they're funny. Stuff like, "Aliens have made me thier love slave", and the like.
So "SURGEONS FIX BOY BORN WITH HIS HEAD ON BACKWARD", "Psychic Advice from Serena", and "PANIC! World economic collapse will come in June" Didn't tip you off? It's the Weekly World News - the greatest paper you can find at the checkout counter - the only one that hasn't devolved into celebrity gossip and has stayed true to its mission of bringing us the facts about UFOs, the Face On Mars, the Loch Ness Monster, the Hoax of a Moon Landing our government fooled us with, etc... I especially like Bat Boy (and maybe the covershot on that page will give you a better idea of the paper's nature).
Nothing useful has ever come of giving up on things.
I don't watch exfiles. I don't see Aliens, and I don't think alien visitations are very likely.
I do think alien civilizations exist.
I don't think it will be very easy to contact them.
I justify all three of these opinions withb one thing. Space is really really really BIG. At our present technology level I belive we could here somebody else at the same level a hundred light years out at most. That's only a few hundred star systems.
In this galaxy, (one of about 200 Billion) ther are about 400 billion stare systems. That means there could be as many as a billion civilizations in our galaxy alone and we could not here them.
If we extend our detection out to a thousand light years (the square kilometer thing?) then there could still be at least a million out there and we woudn't know.
I doubt there are that many. Most likely, however there are some.
The potential gains in contact more than justify the voluntary contributions that you seem to think it's your business to complain about.
The technology has an immediate dual use in radio astronomy and can be expected to create many other things as the technology is pushed.
Question Reality
Why would an advanced technology communicate at the speed of light? SETI searches are somewhat like looking for smoke signals while standing next to fiber optic central office.
Hell, with a big dish it's worthwhile using cryogenic cooling of your preamp. Get your preamp down to 3K and you cut the noise quite a bit. But add up 6000+ dishes, and you add the noise from all those preamps.
Now as for interferometry, it's great stuff if the goal is precise angular resolution. Mapping structures in the center of galaxies and the like.
But for SETI, there's nothing to map until you find a signal, and to find a signal you need sensitivity. Breaking the sky into smaller bits doesn't help push down your noise floor significantly.
I would also like to see SETI be able to scan more of the sky, but realistically that requires the use of a few large steerable dishes. They won't be quite as large as Arecibo (~100m rather than 300m), so Arecibo will do a better "depth" search, but they both should be done.
Being enthusiastic about the tech is great; it helps if you actually know something about it.
I run seti from a bunch of machines in the office. Everyday the tech guy, I like to call him Dan (dumb ass nuisance) asks if I found andy spacemen. Small minded jerk.
It seems to me that, if the people behind this play their cards right, they could get a boost from amateur radio astronomers. If the plans & software for these systems were published on the net, I would imagine that a few hobbyists might actually build a small network of these telescopes in their backyards (I can just imagine them driving around scrap yards looking for abandonned dishes). Science has small questions as well as big questions, and the cumulative answers to a series of small questions can add up to something significant. I'm sure that professional astronomers could find a use for amateur collected data. I remember a story from my college days about the first paper submitted to the Astrophysical Journal on radio astronomy. The author (I'm sorry but I have forgotten his name) was not a professional astronomer; he was a technician at a radio station in a small town Illinois. The story is that Otto Sturve, who was ApJ editor at the time, couldn't find anyone to peer review the article because radio astronomy did not exist as a specialty. So he hopped a train (the ApJ is published by the University of Chicago), and paid the author a visit. He inspected the equipment and asked the author about his methodology. The he went back to Chicago and published the article. Amateurs have always played a role in astronomy. Anonymous Me (too lazy to log in)
Linux probably isn't any more suited for the job than anything else... except it will save taxpayers' money. Which is a good enough reason, IMHO.
"Free your mind and your ass will follow"
-- seti.krisjohn.net
Anyway, I think the last /. article with a mention of Radio Astronomy was in regard to the Iridium Sats, so were' not all just SETI. Other recent space science stuff has been about extrasolar planets, which just happens to be optical astronomy at the moment (planets are being found using light intensity changes and red shifts, not radio waves...)
I read the article on the Planetary Society site, and it's not clear to me why this is a good idea. Sure, you might get a stronger signal from a narrowband laser pulse, but the sender would have to be pointing it directly at us for us to get the signal. Why would the sender decide to point it in our direction? Seems pretty improbable.
:)
Then again, if you have read more on the subject, and it isn't actually as bogus as it sounds, maybe you can enlighten us
SURGEONS FIX BOY BORN WITH HIS HEAD ON BACKWARD Since they figured he'd never be able to get a date, anyway....
/.
/. If the government wants us to respect the law, it should set a better example.
Because I'm a queen? I also happen to be a FEMALE, but I can see you don't know how to talk to a lady.
The Divine Creatrix in a Mortal Shell that stays Crunchy in Milk
The House Between - Original Sci-Fi Series
Oh sure, I can see it now; accusations flying of people flooding the SETI servers with dozens of virtual satellite dishes, trying to boost their team scores...
I use Macs for work, Linux for education, and Windows for cardplaying.
Well, of course it will be a tradeoff, but probably not a bad one. Even with signal processed receiver arrays used to "aim" Arecibo, it's still limited by physical geography in a lot of ways. Needless to say, building another 300-meter instrument (at another latitude, for instance) would cost much much more than several dozen or even hundred commodity dishes with custom ultra-low noise preamps and receivers.
I'm not a radio astronomer, but it seems this will lower the entry barrier and put serious deep sky work in reach of a lot more researchers. Maybe these commodity arrays won't replace big dishes, but they certainly have the potential to accelerate research in radio astronomy.
Mozilla
My read on the article is that they are making their *own* array out of off the shelf like dishes, in order to keep costs way down. I do not see anything that says they are going to be doing 'distributed data acquisition' by linking together your and my satelite dishes. But the latter is a damn neat idea eh?!! I wonder what the challenges would be for such a thing? Probably 'tracking' and 'electronics', with everyone having different dishes and gains and stuff... It sounds like they had to do some work in order to make these things do what they want for their purposes, and now they're testing all of that... attempting to put together something that would work for all of our backyard dishes would be a lot more complicated, and there would likely be some extra cost (for someone) to 'upgrade' our dishes...
I'm recalling some of this from an Astronomy class I took over a year ago, so I don't remember a lot of the details on how this works. But if I remember correctly, it's not a case of needing 6000+ telescopes to 'equal' Arecibo. Using something called Radio Interferometry, you can have two medium-size telescopes a kilometer apart, and have them function as one big one (for an accurate, detailed description of how Interferometry works, check out this site.Examples of existing telescope arrays using this technology are the LBA and the VLBA, which I think stands for 'Long baseline Array' and 'Very long Baseline array,' where they stretch out over several miles--I think the VLBA is in New Mexico. I may have either the acronyms or the meanings messed up, but I think that's the gist of it.
What we _need_ for SETI is a LARGE radio dish on the "dark side" of the moon... sunk in a crater or something. That way the moon would filter out most of the Earth radio noise... and due to the lower gravity, it will probably be easier to build a bigger dish.
:-) That is why the space program is so VERY VERY vital to the future of the human race.... we need to spread off this planet, and into the unknown. Besides, what else is there to do? :-) j/k
I really wonder why people say "why do we keep throwing money towards SETI?"... I say why not? I mean what do we do on this world that is so great. We are here to serve life itself... finding other life is part of the duty we have.
Ryan
Do'h
I can see various applications, such as cheaper ways to communicate with satellites & space probes, cheap ways to do the "easy" radio astronomy somewhat better. (Like studying radio pulsars, etc. without using the big-time arrays), and even just for a teaching and prototyping tool.
I didn't see much mention of *that* in the MSNBC article....
Insanity is the last line of defence for the master diplomat. But you have to lay the groundwork early.
Well, from "pure" technical point of view, there's
very little "new" stuff here. The point is to figure
out a way to build them cheaply. Almost everything
in Astronomy is astronomical, especiall the cost.
For example, it will be considered a bargin if one
can build the SKA for less than half billion USD.
So to use off-the-shelf components is
essential. Those dishes may not be the best ones
out there, but you will need thousands of them
before it is done. So are the LNAs and the
Correlators, and the computing units needed.
It comes down to MONEY, 100s of millioms of
US dollars at least. If you insist on using
"cutting edge" technologies, you'll be talking
about billions of US dollars.
So, once this is fully in place, not only will they have folks all around the world crunching numbers for them, but they'll have folks all around the world listening for them as well. Now *that's* cool.
It makes sense, though. One of the arguments for helping SETI was that your computer is idle most of the time. Similarly, your satellite dish is also idle most of the time; why not make use of it?
Now, if I only had a satellite dish...
darren
Cthulhu for President!
(darren)
While it is true that the energy gathering capability of the smaller dishes is much less than the large antenna at Arecibo, the resolution of the signal is not a factor of the gathering area so much as the position of the antenna. 100 12' dishes scattered over 1000 miles would act like a 1000 mile dish, except that the actally intensity of the signal would not be as great.
Gonzo
And making the thing 'expandable' is not really revolutionarry in my opinion.....
Grtz, Jeroen
Secure messaging: http://quickmsg.vreeken.net/
To put this in perspective, you need to have 6,824 of the little 12 foot dishes to equal the collection area (and hence sensitivity) of Arecibo...
1)transmitted beams of visible light (ie. lasers) can be finer than beams of radio waves due to the higher gain of optical telescopes. I suppose this means that the signal can be more concentrated and thus brighter and more easily detected.
2)visible light doesn't disperse as much as radio waves. This also increases the intensity of the signal.
3)the capabilities of radio transmitters has hit a brick wall while optical lasers continue to increase in power. This is assuming that an alien race is similarly limited as to the power of their radio transmitters. All this leads us onto the question of how effective signals sent with visible light are. The answer is very. The article says that with our current technology, we can send laser transmitions that would outshine the background light from our sun by 5000 times. So assuming that an alien civilisation has more powerful lasers than us, we should easily be able to detect any signals they send in our direction.
Also, the equipment needed for an optical SETI search is very simple. All it involves is a pair of photon-detectors. Current optical SETI equipment works on the premise that any optical signals from alien civilisations will be sent in pulses. I haven't had time to purse the explanation on how the detector works so I can't tell you yet. Perhaps someone else with access to the latest Planetary Report could help out here.