Searching For Life In Space - extraterrestrial life - includes related articles on helping to search and planets

Current Events, May 7, 1999

Radio Telescopes and Missions to Space Search the Heavens for Signs of Life and Alien Civilizations

The SETI Institute uses radio telescopes like the one illustrated here to search the skies for signs of intelligent life. Scientists at SETI hope that such devices will allow them to pick up signals from faraway civilizations.

Are we alone in the universe? Or do other beings, other civilizations, exist somewhere in the vastness of space? Those are questions that humans have puzzled over since our first ancestors looked with wonder into the night sky.

Giant Triangles and Mirrors

Throughout history, humans have thought of ways to communicate with space aliens.

* In 1820, German mathematician Carl Friedrich Gauss proposed carving a large right triangle in the Siberian forest so any aliens passing by the planet could see the symbol and recognize that intelligent life exists on Earth.

* In 1840, Austrian astronomer Joseph Von Littrow thought a group of giant flaming ditches in the Sahara would be the best way of getting the attention of possible extraterrestrials.

* In the 1860s, French inventor Charles Cros proposed building seven giant mirrors to reflect the sun's light toward Mars. The mirrors, Cros said, should be shaped like the Big Dipper constellation to let any Martians who might be looking at Earth know that they are not alone.

SETI

Today, scientists are doing more than just proposing the building of giant mirrors or the digging of huge ditches. They are spending millions of dollars in a worldwide, high-tech search for signs of life beyond Earth.

Throughout the 1990s, scientists at the SETI (Search for Extra Terrestrial Intelligence) Institute in Berkeley, Calif., have been working to find any signs of other intelligent civilizations. SETI listens for signals from outer space through radio telescopes--telescopes that act much like giant ears, listening for the sounds generated by the universe.

Humans have been broadcasting radio and television signals for more than 60 years. Those signals don't travel from place to place only on Earth; they go out into space as well. SETI scientists say that if alien civilizations exist, they might have developed radio and television technology, and they could be broadcasting signals of their own. Aliens might even have received and be responding to our TV and radio signals.

One of the most exciting projects at SETI is the building of its own giant radio telescope, called the One Hectare Telescope, or lhT. Rather than consisting of just one large telescope dish, the 1hT will be made up of between 500 and 1,000 small antennas, similar to backyard TV satellite dishes, spread over 1 hectare (about 100,000 square feet) of land. At that size, the lht will be many times larger than the Arecibo (Puerto Rico) telescope (a single dish telescope), currently the largest in the world.

The 1hT will also be more powerful than the Arecibo telescope. When completed in 2004, the 1hT "will have unique capabilities for observing objects from the solar system to the edge of the universe," said Leo Blitz, director of the University of California-Berkeley Radio Lab. Because the lht will belong to SETI, scientists will be able to search space 24 hours a day, 365 days year.

Other Searches

SETI scientists are already searching the skies for intelligent life in many ways:

* Project Phoenix: Run by SETI in Mountain View, Calif., Project Phoenix performs targeted searches for the sounds of alien civilizations. Rather than scanning the whole sky, Project Phoenix scientists direct a radio telescope only at nearby, sunlike stars. In addition, Project Phoenix scientists set the telescope to search out radio and TV signals at frequencies they say are most likely to be used for communications. Because the stars that Project Phoenix targets are similar to the sun, scientists say, they are more likely than bigger or smaller stars to have planets (like Earth) in their systems that can support life.

Project Phoenix scientists started in 1995 using a 64-meter radio telescope in Australia and continue to move to sites around the world trying to pick up signals from its chosen targets. Project scientists are currently using the 305-meter Arecibo radio telescope in Puerto Rico.

* Project Beta: Project Beta (The Billion-channel Extra-Terrestrial Assay) takes an approach opposite that used in Project Phoenix. Beta leader Paul Horowitz of Harvard University and his team use a radio telescope at Harvard University to sweep the entire sky over the course of a year, instead of aiming at specific targets. The team listens for a specific frequency that it believes would be used by aliens trying to be noticed.

Another project called META II is similar to BETA. In the South American country of Argentina, the Argentine Institute scans the skies in the Southern Hemisphere. (If you were looking at a globe, the Southern Hemisphere would be the half of the world south of the equator.)

* SERENDIP IV: SERENDIP stands for Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations.