Life Beyond Earth I (School)

File: UFO333

Searching for Signs of Intelligence

JPL has launched a survey of the sky using radio telescopes. The High Resolution Microwave Survey (HRMS) will map the entire sky over the next several years. Part of the survey is the search for extraterrestrial intelligence, also known as SETI. This is not a wild-eyed search for the type of "aliens" that routinely turn up in supermarket tabloids. It is a careful examination of space around us. In fact, HRMS will just "listen;" no signals will be transmitted.

The HRMS is managed from the Ames Research Center in the San Francisco Bay area. JPL is a collaborating center. The JPL part of the project will use radio telescopes of the Deep Space Network in California and Australia. Ames will head a search of selected targets with a huge 300 meter (1000 foot) radio telescope in Puerto Rico. The extremely sensitive receivers began the search on Columbus Day, October 12, 1992.

We already know that the sky is filled with radio energy. But the HRMS will also be listening for non-natural sources. Scientists have determined that the radio portion of the electromagnetic spectrum is one of the best places to search for signs of extra-terrestrial life. Radio waves, especially at some frequencies, appear much more powerful compared to the natural background of the sky. Visible light signals would have to be extremely strong at their source in order to be detected over even short distances. After all, stars are huge balls of glowing gas but none, except our own Sun, is even bright enough to cast a shadow.

Radio signals can travel through dust and gas clouds that would block out or scatter visible light. But this does not mean that our radio and television broadcasts would be detectable by an alien civilization or that we can expect to eavesdrop on their equivalent of soap operas or athletic shoe advertisements. Our radio, TV and radar transmitters send energy out in all directions. The signals get weaker as they get farther and farther from the transmitter.

The energy falls off by the square of the distance. If one receiver is twice the distance from a transmitter than another, the energy is not 1/2 but only 1/4! At three times the distance, it is 1/9, at four times it is 1/16 and so on. Very quickly the signals get too weak to be casually detected. But an alien intelligence that was interested in communicating would send out a focused beacon, perhaps like a lighthouse. The signal would be able to travel at the speed of light for many years. Of course, in order for their beacon to be detected, someone would have to be searching.

Searching is exactly what the High Resolution Microwave Survey will be doing. Using radio telescopes, the entire sky will be scanned. Unexpected or unusual signals will automatically be extracted from the data by computer. Scientists will then examine that data. If something intriguing turns up, a more detailed examination can be made.

What will happen if signals suspected to be of extra-terrestrial origin are detected? Will the scientists keep it quiet? The project has given these questions careful consideration. The technical information will be given to independent observers so that they can confirm the findings. This will avoid embarrassment and confusion over misinterpretation. Then, the information will be released to the public.

Most likely, the finding will be that we have found something like a lighthouse beacon. The distance to the source is likely to be so great that conversations will be impossible. To communicate with a civilization on a planet 50 light years from Earth (right next door by astronomical standards) would take a century round trip. The signal we receive would already be 50 years old. Do the senders live longer than we? Did they send out a signal knowing that only their children and grandchildren might get a reply? Can we even hope to ever understand each other?

The High Resolution Microwave Survey will only cover a comparatively small portion of our galaxy. Our galaxy is only one of hundreds of billions of galaxies. Galaxies contain tens to hundreds of billions of stars. Project scientists might find signs of intelligent life, they might find interesting new natural objects, or they might find nothing at all. There might be life elsewhere in the Universe, or we might be completely alone. We will never know unless we take a look. It is a search for a golden needle in a cosmic haystack.

Is Anybody Out There?

And what if the answer is "Yes"...?

There is no assurance that the High Resolution Microwave Survey will find evidence of extraterrestrial intelligence, but the search itself is certainly thought provoking. The SETI (Search for Extraterrestrial Intelligence) Institute, a non-profit group that is supporting the project, is developing educational materials for elementary students.