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New Telescope Array Goes Live For SETI
The Skinny writes "Today is a historic day for the SETI program. The New York Times reports that astronomers are flipping the switch today on the Allen Telescope Array — 350 antennas, each 20 feet in diameter — which will, among other things, extend the search for extraterrestrial life a thousandfold. From the article: ' There are some 200 billion stars in the galaxy, and a significant fraction of them have planets. Estimates of the number of intelligent civilizations in the galaxy have ranged from one (or none, if you are particularly discouraged about human affairs) into the millions. Dr. Shostak calculated that the full Allen array would be able to detect a signal from as far as 500 light years that is only a few times more powerful than what can now be sent by the Arecibo radio telescope, a 1,000-foot-diameter dish in Puerto Rico that is the world's largest (although it is in danger of being shut down to save money). That translates to about a million stars, which he said was getting into a promising number. Dr. Shostak described the expanded search as looking for the needle in the proverbial haystack with a shovel instead of a spoon.'"
Only 42 installed so far. They are looking for donations to complete the array.
wot no sig
Inverse Square Law
Seth Shostak ( http://en.wikipedia.org/wiki/Seth_Shostak ) is a very entertaining and informative speaker of SETI topcis. See/hear him if you get a chance. He's a fun combo of dry, acerbic, and self-deprecating.
Two wrongs don't make a right, but three lefts do.
I wonder if this new publicised technology is better than seti@home, which was eclipsed by the jarvard META array, before it was even launched (the META array could do the job of SETI@home, in real time, and was retired in 1995 for the BETA, which has orders of magnitude more power). As long as SETI is dominated by PR stunts like seti@home, however, it'll never go anywhere
http://www.torrentfreak.com
http://neuron2neuron.blogspot.com
http://www.piracyisnotacrime.com
Maybe not....
Study Predicts Trillions Of Planets http://dsc.discovery.com/news/afp/20030922/universe.html
NASA estimates the number of terrestrial planets to be as high as 30 Billion: http://astrobiology.arc.nasa.gov/news/expandnews.cfm?id=1227
(And both articles are several years old...)
Although I agree with the rest of your comment, I don't think burning money is wasting it. If you destroy currency you are removing it from circulation, which will cause prices to go down due to deflation.
If you truly want to waste money, you should buy something of value to others and destroy that thing. The grandfather post would be right, if one assumes that scientific research has no value. However, that is very seldom the case. Research is almost always valuable, even if it turns up nothing. Negative results are also knowledge. If we find no sign of extraterrestrial intelligence in our search we will know more than we did before about the abundance or scarcity of intelligence in our galaxy.
There are solid scientific reasons to believe that we are unique. Rare Earth Hypothesis
Duh. A few more clicks and I would have found the answer: http://en.wikipedia.org/wiki/Free-space_loss -- the short version being that it's the diameter of receiving antenna that gives the frequency dependence.
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
It's not "a bunch of little telescopes". It is one large phased array. The signals from all the antenna are added in phase. By controlling the delay from each antenna before adding the signals they can point the beam around in the sky. By building more "adders" they can have multiple simultainious beams.
Think of each dish antenna as an element of a single larger antennta
They are NOT listening for random signals like the type that are leaked out from Earth. The array is not sensitive enough for that. What they are hoping to find as a beacon. A huge transmitter beamed right at us. If they find such a thing then we might reasonably guess there is a signal on it. We would not have to wait for 2-way communication to learn a lot. Heck even if all we got was a "Hello Earth" greeting that in itself would be one of the greatest discoveries in all of history.
I doubt there are any huge microwave beacons. If we do discover anyone out there it will only be after our arrays become powerfull enough to hear the "leakage" signals that only escape by chance, like the signals we are currently sending. But we could get lucky. It's like buying a lottery ticket.
I think you're underestimating the antennas involved here. Arecibo (which is the biggest telescope we've got) has a gain of approximately 140 dB. But the Allan Telescope Array will have a gain only about 10 dB down from that with 42 antennas, and with 350 antennas, it will have a gain of ~170 dB. So if they transmit with an Arecibo, and we listen with a 350 ATA, then Proxima Centauri will come in loud at 30 dBm, and we can see out probably a factor of 100 out past that. It's only a small part of the galaxy, but it's not hopeless.
The SETI Institute is an organization that employs many scientists. A few of the scientists there do SETI (i.e. they search for extraterrestrial intelligence). The vast majority do not. The SETI Institute, in collaboration with the University of California Berkeley, are building a telescope called the Allen Telescope Array. Some of the scientists at the SETI Institute will use it for SETI. Other astronomers will use it for non-SETI related projects.
SETI@home is a project at the University of California Berkeley. It is neither funded by nor affiliated with the SETI Institute. In fact, some SETI scientists at the SETI Institute, dislike SETI@home because it directs attention (and therefore funding) away from SETI Institute projects. Competing projects also have some at the institute worried that someone else may be the first to detect extraterrestrial intelligence. For those reasons it is unlikely that SETI@home will ever be allowed to utilize data from the Allen Telescope Array.
From my vantage point, it appears that this confusion is promulgated by the SETI Institute. They would like the world to think that they are in control of all SETI related projects, and they would very much like to control all SETI related funding. At this point they feel that there is no advantage to preventing this confusion. In fact, scientists at the SETI Institute often drop the word "Institute" when they mention their affiliation, and just say they are "from SETI" or "with SETI".
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SERENDIP, META, and BETA are essentially simple FFT processors, with BETA essentially being four 80 million channel analyzers. That is proof that to an astronomer 240 million is equal to a billion. SERENDIP IV (the last one deployed) was a 168 million channel analyzer. Both had channel widths of about 0.5 Hz (0.5 Hz for BETA, 0.6 Hz for SERENDIP). The channel width limits the sensitivity. Simple FFT analyzers cannot go to narrower channels without correcting for Doppler drift which will chirp the signal out of the channel in less than the integration time, and because the Doppler drift depends upon the properties of the transmitter in addition to the motion of the Earth, it's not a simple process that can be done on the fly.
SETI@home implements coherent dechirping which allows for channel widths of 0.075 Hz or less. In essence you are changing maximum coherent integration time on a signal from 2 seconds to (in SETI@home) about 13 seconds for simple (single time bin) signals. In addition SETI@home searches at higher sensitivity for multi-time-bin signals with up to 107 seconds integration. SETI@home also searches for repeated (fixed period) pulsed signals, which none of the special purpose instruments can do.
Now add the consideration that SETI@home (and the Berkeley SERENDIP instruments) uses a telescope with a collecting area 140 times as large as the telescope used by BETA.
If you calculate the maximum value of the processing power of BETA, (a 240 million point FFT every 2 seconds) you get 16 GFLOPS. That's an overestimate because a) it's not a floating point processor, but an integer processor, and b) it's implemented as sixty three 4 million point tranforms.
SETI@home, on the other hand, currently cannot handle real-time data from the ALFA instrument because it only has about 1/3 of the 1.2 PFLOPS it needs to process at that rate. In other words to do the same processing as SETI@home does, you need to build 75000 BETAs.
That's not to say BETA (and the SERENDIPs on which it was based) wasn't worth the effort. At the time it was among the best. SERENDIP V will eventually take over where SERENDIP IV left off, so the age of the SETI hardware based spectrometer isn't over.
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