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SETI, or the Search for Extra-Terrestrial Intelligence, is the scientific search for signals, primarily radio signals, from outer space. It is based on the belief that we will hear extraterrestrials before we see. The organizations work has been going on ever since the 1960 s. The main tools the scientists / searchers use are radio telescopes and listening equipment. To understand this organization, one must first look at its rocky history, and its unique discoveries. The Beginning of SETI is relatively simple, in 1959 Guiseppi Cocconi and Philip Maorroson published an article in the British Science Journal Nature in which they pointed out it would in principle be possible for civilizations to communicate across space using radio waves.
This theory brings two possibilities, one that we might be able to listen in on another civilization and that they might be attempting to communicate with us as well. On April 8 th, 1960, Frank Drake, now the President of the SETI Institute, launched the first SETI search, called Project Ozma. Drake had a job at the National Radio Astronomy Observatory, in Green Bank, West Virginia, which had recently purchased an eighty-five foot radio signal receiver. This isnt quite as nice as a radio telescope, but it was the limit of the technology in the sixties. Drake and his students heard a signal from a nearby star, but it soon quieted.
The surprised group heard the signal again a week later. Unfortunately, they soon found out it was the noise from airplanes flying overhead. This put a slight damper on the SETI movement, though it didnt stop it. SETI was continued by independent and amateur scientists who owned or had access to advanced telescopes. NASA took over the project in the mid seventies. This move brought ridicule from many people.
SETI was thought to be a waste of Nasa's money and time. In 1981, Wisconsin Senator William Promise cut Nasa's funding of SETI for a year, but luckily it was renewed the following year. Throughout the later 1980 s, Seti's most ambitious research started. They launched their final result project in 1992.
It was called the High Resolution Microwave Survey. The search included using the 1, 000 -foot wide Arecibo radio telescope in Puerto Rico to listen closely to the 1, 000 nearest stars and sweeping the entire sky with random telescopes around the globe. Soon after this project was started, SETI had more trouble. Richard Bryan, the Democratic senator of Nevada at the time, banned any more NASA funding of SETI. The anti-SETI Bryan said We cannot afford a program as remote and uncertain as this. The people of SETI searched anxiously for new sources of financial support.
In 1995, they received private donations, totaling around $ 4 million, and started the SETI Institute, the same institute where Frank Drake is now president. Even though SETI has been listening to the skies for over forty years now, no proof of any other intelligent civilizations has been found. This fact doesnt discourage the optimism of the SETI scientists though. Over the years there have been some interesting findings. On August 15, 1977, Jerry Ehman, a SETI volunteer and Franklin University astronomy professor, was working at the Big Ear Observatory outside of Columbus, Ohio. Ehman was looking at the computer printout and spotted something interesting.
He circled the unusual section and wrote Wow! in the margin. This signal has been called the Wow! Signal ever since.
It was thirty times stronger than the surrounding background noise and only covered a small range of frequencies, much smaller than any natural signal. It had all the signs of a signal from a remote source in space, but never recurred despite many follow up observations and may simply have been the reflection of a powerful signal from earth reflected by a piece of space debris. The observatory has continued monitoring the constellation Sagittarius, the spot where Ehman heard the signal, but nothing with that magnitude has been heard ever since. Radio signals are broadcast from many sources. Scientist have to sort through cell phone signals, TV, radio stations, satellites, and even aircraft flying overhead. In addition to signals from earth, there are other, natural, signals from space.
A star gives off radio waves that are picked up as a clicking noise by radio telescopes. A solution to this background noise problem is Project Phoenix. Project Phoenix started after 1993, when the NASA SETI was cancelled. The project is funded by the SETI institute and other private sources. The main difference between Phoenix and normal SETI is the software technique.
SETI scans the skies for any and every signal frequency from anywhere in space. They pick up a lot of background noise that makes it harder to spot a new signal. Project Phoenix's computers are programmed to listen to about two billion separate, very narrow radio frequencies. This makes picking out intelligent signals over natural ones easier. Natural signals tend to go over a wide range of signals. Intelligent signals, radio stations for example, only cover a small frequency range.
The one draw back with Project Phoenix is that it only scans the 1000 stars closest to us. To cover for the billions of more distant unchecked stars, another SETI funded project, SERENDIP, was started. The telescopes used by researcher for SERENDIP slowly scan the entire sky for any type of signal. These two projects combined make sure that SETI will hear a signal when it comes.
Another impressive series of searches has been carried out by the Harvard SETI group. There project META, which operated from 1985 until 1994, found 37 candidate events but none have been observed in follow up observations. They are currently using a 26 m antenna feeding 80 million channel receiver in Project BETA to carry out a full survey of the northern sky. Despite all of the negative response from the government, SETI has continued to search for extraterrestrial life. After the NASA funded SETI was terminated, and before the SETI Institute was formed, the SETI League was created. The SETI League was an organization of amateurs and hobbyists who also wanted to find signals of intelligent life.
The satellites used by the amateurs arent as sensitive as the ones used by NASA, so they cant detect as many signals. The people of the SETI League believe that when a signal comes to earth, it wont be faint but will be an ultra-powerful Hello. With all of the different efforts searching the sky for signals, when one arrives here it will surely be detected. The search's importance is not to be underestimated, because it could mean finding intelligent life other than our own. Bibliography Chang, Kenneth.
Are We Alone? Retrieved October 15, 2000, on the World Wide Web: web intro. html The SETI Institute Online. Retrieved October 20, 2000, on the World Wide Web: web Angelo, J. (1991). The Extraterrestrial Encyclopedia. New York: Oxford.
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Research essay sample on Radio Telescopes Radio Signals
