Scientists and theologians who gathered in Washington to discuss the origins of life and the Universe ended their conference by trying to answer the question: "Are we alone?"

Astronomers discoverd three planets orbiting a distant star

The question seemed particularly fitting in light of the past week's announcement that astronomers have discovered three planets orbiting a Sun-like star 44 light-years away.

David Latham is an astronomer who has carried out research into extra-solar planets by observing the gravitational pull the planet exerts on the star it orbits, by causing the star to "wobble."

"It's an exciting time for planet research," he said, adding, "this will have an impact on our thinking about intelligent life elsewhere."

But as to whether these newly discovered planets could support life, Latham said that the planets are nothing like Earth.

Inhospitable giants

They are several times more massive than Jupiter, the biggest planet in our solar system, and just like Jupiter are probably inhospitable gas giants, he said.

But while astronomical observations can detect the presence of planets around other stars, we can only measure the most basic attributes of the planets, such as their orbit and a minimum mass, Latham said.

We have yet to measure whether these planets have features that would support life. According to Ken Nealson, some of these include:

• the presence of liquid water
• plate tectonics
• and a magnetic field to shield the planet from cosmic radiation.

Ken Nealson will analyse samples from Mars for signs of life

Nealson is a senior research biologist with the Jet Propulsion Laboratory. He is working on future missions to Mars, which will look for signs of life on the Red Planet.

The mission will bring back samples from Mars, and Nealson predicts a leap in scientific knowledge similar to the great leap forward in knowledge that took place after the Apollo missions brought back samples from the moon.

The mission has generated great excitement and interest in the scientific community. "We're no longer on the fringe," he said.

Contact

Jill Tarter is the director of Project Phoenix for Seti, the Search for Extraterrestrial Intelligence. She is the model for Jodie Foster's character in the film "Contact."

When her daughter was eight years old, someone asked her what her mother did. Tarter's daughter answered: "she searches for little green men."

But, she was quick to note that Seti is "not an investigation of UFO's or alien abduction. It is not a religion or a cult. It is not a way of directly detecting alien intelligence. It is also not politically correct."

Seti was formally a federally-funded project under the auspices of NASA, but the groups funding was cut in 1993. The group now relies on private funding.

Human intelligence

To detect extra-terrestrial intelligence over interstellar distances, they listen for radio transmissions.

But Irven DeVore, an anthropologist at Harvard University, said that six of eight conditions necessary for life are highly improbable.

On Earth, the development of human intelligence was itself highly improbable, if "nothing but fortuitous."

For these reasons, he said, "the chances for communication with another intelligence are vanishingly small."

Although they disagreed on the possibility of extra-terrestrial intelligence, Ms Tarter and Mr DeVore agreed that if we did make contact with intelligent life from another planet, it would be a monumental event.

"Contact with an extra-terrestrial intelligence would be such a momentous event that everything else would pale in comparison," Mr DeVore said.

Seti is ready for the day they hear a signal from space.

Ms Tarter showed a picture of Seti's refrigerator at the radio telescope in Arecibo, Puerto Rico. They have a bottle of champagne waiting ready for the celebration.