We've looked at some Of the Attempts To communicate with extraterrestrial
civilizations. How do we look for extraterrestrial
intelligence. What sort of approaches are used. Well, there's no one mission to search For extraterrestrial intelligence in the
SETI program. It's rather a collection of scientific
programs designed To detect signals of extraterrestrial
intelligence in the universe. The origins of the Search for
Extraterrestrial Intelligence began in 1957 after the building of the Lovell
Radio Telescope in Manchester. It was realized that once we had built Radio telescopes, we could use them to do
radio Astronomy, but we could also use them To search for signals for alien
intelligences. Cocconi and Morrison proposed that it
would be Worth using these telescopes to look for
extraterrestrial intelligences. And this is what they said in 1959, they
said that the probability of success Is difficult to estimate, but if we never
search, the chance of success is zero. Well, there are number of ways to search
for extraterrestrial intelligences. One way is to look for optical signals,
light signals, from alien intelligences. Another way is to use radio waves, the
same radio waves That are used by radio stations to
transmit music and other information. The problem is that there is pollution
from space. There's noise, background noise in space, And also background noise from the
atmosphere. So, we need to tune into specific narrow
frequencies where The background noise is low, and where we
have a greater Chance of picking up alien signals. The first attempt to do this was made by
Frank Drake in 1960. He and his colleagues used the 84 foot
Tatel Telescope in West Virginia to scan for
extraterrestrial radio signals. They targeted two nearby sunlight stars.
They didn't find any signal but this was
pioneering project. Project Ozma was the first project to try
and seek Out signals from alien intelligences. The problem is that radio telescopes are
in high demand by astronomers and so How does a SETI program use these Very expensive resources to search for
alien signals. Well, there are three ways in which people
do this. They rent time on existing radio
telescopes for targeted searches of Particular stars, carrying out very short
searches, but looking at particular stars. They can also run SETI analysis from the
radio telescope data of others. So, people are collecting this data, this Data radio astronomy, and SETI researchers
can troll Through this data to hunt down signals
from Alien intelligences that might appear in
that data. And then, of course, they can build their
own New radio telescopes dedicated to the
search for extraterrestrial intelligence. Project Phoenix which began in 1995 is an Example of a SETI project that rented
telescope Time to search for extraterrestrial
intelligences, and after Looking at 800 stars they found no signal. They concluded that we live in a quiet
neighborhood. Now this was a significant project because
it was the first time a large Number of stars had been systematically
studied For the possibility of signals from alien
intelligences. The SERENDIP Project is an example of a
piggy back SETI search. The SETI researchers put an extra receiver
onto the Arecibo Dish Observatory in Puerto Rico, which is
used by other researchers. And so, they could use the radio telescope
to search for Extraterrestrial signals whilst it was
being Used for doing conventional radio
astronomy. The only problem is you don't have much Control over what stars you're looking at
because, Of course, that's decided by the radio
astronomers doing their other research. But, the benefits of it are that you can
piggy bank on
A large amount of radio astronomy time,
and try and seek out signals. They, too, have not found a signal from
alien intelligences. Yet another project is the Allen Telescope
Array. This is a new SETI search with an Array of over 350 small telescopes that
are planned, Which combine their signal to search for
radio waves in deep space. This project is housed near San Francisco, And heavily funded by Paul Allen of
Microsoft. The project has not yet been completed,
but it's a, it's an example of the Way in which SETI researchers can
establish dedicated Facilities to search for signals from
alien intelligences. So, as you can see, there hasn't been much
success so far In Finding signals from alien intelligences,
and that in itself is significant. There was one signal that was detected in
1977 called the WOW signal, rather famous Now, because some people believe it was a
message from an alien intelligence. The WOW signal was 30 times stronger Than anything that telescopes could
normally detect. It was almost exactly in the place
researchers Expected to find a signal to come from
alien intelligences, at least in the Radio spectrum, and it hasn't been linked
to any earth based emissions or pollution. So, on the face of it, this looks like
rather an Interesting signal, but the problem is
it's never been detected ever again. It's never been found again, and that
suggests that it is an Experimental artifact, maybe an artifact
of The electronics, or the radio telescope, Or something else that we're seeing That has no connection with
extraterrestrial intelligence. So, what have we learned. Well, we've learn that SETI has a very
long history. We've learned that numerous attempts have
been made to detect intelligent signals. There's been no success yet, but
technology Has improved, and might lend itself to Larger and more systematic searches for a Larger number of stars across the
universe.
Particularly stars that we Might find host Earthlike Planets in the future.
