Reaching out to distant worlds; how do we respond when E.T. phones? Scientists are drafting a message to be sure humans make a good first impression. (science times).

THERE IS PROBABLY ONLY ONE PERSON on Earth--although, one hopes, not in the universe whose business card identifies him as "Interstellar Message Group Leader."

That would be Douglas Vakoch, resident psychologist at the Search for Extraterrestrial Intelligence (SETI) Institute in Mountain View, Calif. It is his job to come up with ideas for a response in case any searchers ever discern, amid the crackle and hiss of radio waves from outer space, the equivalent of "Hi there what's your name?"

The receipt of a signal from another civilization, astronomers involved in SETI say, would be one of the greatest events in the history of humanity. The question of how or whether to respond, they say, is too important to be left to the last minute.

"The initial message we send, if we ever do send any, would create the first impression for what would be a dialogue that would be occurring over many generations," Vakoch says.

In the interest of making a good impression--and perhaps counteracting the burble of Friends, automobile ads, and political news spreading outward through the galaxy on radio and television waves--Vakoch is devising a message that encodes the notion of altruism, the charitable quality that many biologists and humanists would like to think is a pillar of any civilization.

It is an effort, he says, that will have value even if there is nothing but silence from the heavens. "By thinking about how we would want to represent ourselves, we're forced to reflect in a different way than we usually do about what our deepest values are," Vakoch says.

THE GALACTIC RADIO

The search for extraterrestrial intelligence has proceeded in fits and starts ever since 1959, when two Cornell University physicists, Philip Morrison and Giuseppe Cocconi, suggested that extraterrestrial civilizations would find it easier and cheaper to reach across the galaxy with radio waves than to visit in person.

The SETI Institute is now halfway through a survey of 1,000 nearby sunlike stars, Project Phoenix--so named because it rose from the ashes of a NASA-sponsored program that was canceled in 1993. The institute's astronomers are already laying plans for another search with new radio telescopes, which will extend the survey to some 30,000 stars. By comparison, there are roughly 400 billion stars in Earth's Milky Way galaxy, but the search technology increases with each improvement in computer-chip technology.

In April 1989, the trustees of the International Academy of Astronautics, an organization of distinguished scientists, approved a protocol outlining how scientists should check out any signal from outer space and what they should tell the world about it. Their final declaration: "No response to a signal or other evidence of extraterrestrial intelligence should be sent until appropriate international consultations have taken place."

Jill Tarter, who directs the SETI Institute's observing program and is Vakoch's boss, has briefed the United Nations Committee on the Peaceful Uses of Outer Space on the need to develop a second protocol on how and whether to reply to a signal.

SENDING OUR SIGNAL

On the flip side, the history of Earthlings trying to signal other worlds, often using scientific symbols to advertise our own intelligence, is long. In the 19th century, mathematician Karl Friedrich Gauss suggested burning or etching giant geometric figures on the surface of Earth as a way of attracting attention from Martians.

In 1974, Frank Drake, then of the National Radio Astronomy Observatory and now the institute's chairman, beamed a message at a star cluster 25,000 light-years away. It was a string of bits--or ones and zeros--that could be assembled into a pictogram showing the figure of a man, a telescope, numbers, DNA, and the solar system.

More elaborate messages have been included on spacecraft like the Voyagers now headed out of the solar system, including a record with sights and sounds of Earth such as music from Bach to Chuck Berry (see "Who Do We Think We Are?" above).

Vakoch is critical of many message schemes. "Just because we're focused on a scientific description of ourselves, that doesn't mean that they will automatically take that as a starting point for a conversation," he says.

MAKING SENSE OF US

That's if they understand what we mean at all. Vakoch is critical of the notion that science can be the basis of communication between disparate species, and he argues that no message could ever be free of ambiguity. And an E.T. would have to know about prime numbers, the laws of physics, even music appreciation, to decipher what we're sending. As a result, he says, "we have no basis for the belief that any part of the message will be intelligible."

Vakoch, who became interested in interstellar messages as a 15-year-old high school student in Minnesota, admits that altruism is a somewhat arbitrary starting point, but a logical one. The radio telescopes used for SETI are too weak to detect signals that have not been broadcast directly at us. "It seems plausible," he says, "that if other beings are sending a transmission, in a sense they are practicing altruism," perhaps in the hope of getting a message and information back in return someday.

Who Do We Think We Are?

For decades, people have been sending signals into space in hopes of making contact with extraterrestrial beings. Here are some of the messages from Earth.

MARCH 2, 1972 & APRIL 5, 1973

The Pioneer 10 and 11 spacecraft are launched into deep space, each carrying a message in the form of a gold plaque showing human figures, Earth's location in space, and a hydrogen atom.

[ILLUSTRATION OMITTED]

NOV. 16, 1974

A string of data is sent toward a cluster of stars 25,000 light-years away. It can be assembled into e pictogram of a man, a telescope, numbers, DNA, and the solar system.

[ILLUSTRATION OMITTED]

AUG. 20 & SEPT. 5, 1977

Gold-plated phonograph records are launched aboard the Voyager I and 2 spacecraft. The records contain specific Images, sounds, and music of planet Earth.

[ILLUSTRATION OMITTED]