Posted on 03/28/2004 8:38:01 AM PST by Momaw Nadon
Astronomers have completed their most sensitive search yet for radio signals from intelligent life in space.
They believe the best way to find ET is to look for a radio signal. Such signals can travel vast distances.
The Arecibo radio telescope in Puerto Rico, supported by Jodrell Bank, searched over a period of 10 years.
The scientists looked at 800 nearby stars with no evidence of a signal from ET. They say they have learned a lot, and plan another search next year.
From the ashes
The last star scrutinised by Project Phoenix - the most powerful search for intelligent life in space ever carried out - was HD 169882, a fairly ordinary star lying just 88 light-years away.
The result was that no signals indicative of an intelligent origin are coming from it, at least during the time it was observed.
So if there are any aliens on a planet circling that star then perhaps they are not interested in signalling, or are doing it in a way we cannot yet detect.
Project Phoenix was so-named because it rose from the ashes of a US space agency (NASA) initiative to search for intelligent life in space that was cancelled by US Congress in 1993.
Despite this setback, the scientists involved were determined to carry out their search.
"When the 'termination' order came from Washington, most of the equipment was on lab benches. We were immediately faced with three challenges: raise private money, get NASA to loan us the equipment and get it working," Peter Backus, project manager for Phoenix, told BBC News Online.
After the initial scramble, the scientists managed to get an Extra-Terrestrial Intelligence (ETI) search system built and used it on the Parkes radio telescope in Australia in February 1995, just one month later than the original Nasa plan.
No signal
Much of Project Phoenix's time was spent on the world's largest radio telescope, the 330-metre dish at Arecibo, which takes advantage of the natural topography of Puerto Rico's mountains.
"Over the years we have observed about 800 nearby stars over billions of frequency channels at high sensitivity," says Backus.
"No other search covered as many frequencies or achieved the same sensitivity. It was the only search capable of detecting ET transmitters with power comparable to our own military radars."
One of the problems in looking for signals from intelligences in space is that signals from Earth can interfere, so the scientists have to have a reliable way of discriminating between ET and terrestrial interference.
Phoenix pioneered a technique of "real-time interference monitoring" using a second radio telescope to determine if any suspicious signal was actually coming from deep space.
Expanded search
No suspicious signal survived that test, but the astronomers are not down-hearted; they know that ET could be detected tomorrow, in a thousand years, or never.
They say a search with an outcome that could be one of the biggest scientific discoveries of all time is worth the effort.
"We've learned a lot about searching for Eti. We'll carry those lessons and the new search system to the Allen Telescope Array (ATA)," Backus adds.
"Later this year, we'll be using the ATA with 32 small dishes. As the array expands, we'll start a new targeted search covering several hundred thousand stars.
"As I look back over the past 10 years I'm very proud of what we have achieved - the most sensitive and comprehensive search of our galactic neighbourhood.
"Conclusion: we live in a quiet neighbourhood."
"Conclusion: we live in a quiet neighbourhood."And the school district is pretty good too.
"point-to-point comm. hub" BUMP
..got my triple layer tin-foil hat on...triple layer you can't be too safe. :)
No, we'll be kept on as wards of the new overlords. We'll simply be declared part of the natural environment and put on an endangered alien species list and our planet labeled as a special endangered alien species habitat. To your ordinary alien life forms, our world will be off-limits or so hopelessly bound in alien red-tape that it's hardly worth the effort to visit us. Only the most elite aliens will be allowed to visit and cherry-pick our planet's resources of minerals, flora, fauna, and personae.
Who knows? It may be happening right now!!!
In a way I agree with you. Moore's law has affected the Drake equation in ways we don't even know yet. I personally think the Fermi Paradox is pure BS and not well though out, however, the Drake equation seems to have stood up to scrutiny.
SETI (at least the current trend) is searching for extremely narrowband carrier signals that Doppler shift due to planetary rotation. The Doppler shift is extremely important since if it is not there, we know the signal is either terrestrial or an artifact of the equipment itself. The other thing that is very important is the two-antenna approach. If two antennas, separated by a thousand miles, were pointed at the same patch of sky, this would not allow a satellite to "spoof" the system. First, the likelihood of it being within the footprint of both antennas are exceedingly small, and the Doppler characteristics between the two antennas would rule it out if such a thing happened.
All that said, I agree with the advances in communications technology can cause a search to be futile for many types of broadcasts. Frequency hopping spread spectrum and the like will make it far harder to detect a tool building species that uses radio (EM).
To be fair to the other side there is another factor in this conjecture. A race is progressing along and figures out that the electromagnetic spectrum is the only real practical method of long-range communications. So high-powered transmitters are built as this technology is in its infancy. As the engineering and science of radio advances, they figure out that tight beam, spread spectrum, synthetic aperture, frequency hopping, etc. are a way of not only saving power, but also bandwidth. So for the first 50 years they have been "bleeding" EM into space across a huge range of frequencies into and ever-increasing sphere of radio noise. However, do to technological advances, this RF that is being bled into space quiets down dramatically.
Now, lets jump a few years. This race has expanded off its initial planet and is exploring the solar system it resides in. (IMHO, star travel still remains firmly in the realm of SiFi) Somehow they have to communicate. So again high power transmitters are employed to accomplish this. Light is not out of the question, however, microwave is easy, cheap, less pointing accuracy requirements, and wont be drowned out by the star. So suddenly this race again is radiating RF into the universe. So according to this scenario, a race can emit RF then grow silent for a time, and then restart emitting RF.
I also agree the movie "Contact" is pretty shallow in many ways. Headphones? Not a chance. Most SETI searches are done with computers looking at millions of frequencies simultaneously. Also, SETI is not looking for, nor is it expecting any modulation. That would long ago have been lost in the Interstellar Medium (ISM). All that can reasonably be expected to be detected a faint signal from the narrowband carrier itself. In fact due to the signal-to-noise (S/N) characteristics, the narrower the band that is being searched, the better. Some searches are looking for signals that are no wider than .8 Hertz.
Just my two cents.
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