Broadcasting a spaceship in hopes of reaching aliens is a controversial idea - two teams of scientists are doing it anyway

While SETI (the search for extraterrestrial radio signals) has long since become part of mainstream science, METI, or the transmission of messages to intelligent extraterrestrial beings, has been a less common field. Two such projects are now underway

By: Chris Impey, Professor of Astronomy, University of Arizona

If a person gets lost in the desert, he has two options. He can search for civilization, or he can facilitate his rescue by starting a fire or writing HELP in capital letters with stones. For scientists interested in whether intelligent aliens exist, the options are the same.

For over 70 years, astronomers have been scanning for radio signals and optical waves from other civilizations in search of extraterrestrial intelligence known as SETI. Most scientists are certain that life exists on many of the 300 million habitable worlds in the Milky Way galaxy. Astronomers also think there is a reasonable chance that some life forms have developed intelligence and technology, but no signals from another civilization have ever been detected, a mystery called "The Great Silence."

While SETI has long since become part of mainstream science, METI, or extraterrestrial intelligence, has been a less common field.

I am a professor of astronomy who has written extensively on the search for life in the universe. I also serve on the advisory board of a non-profit research organization that designs messages to send to extraterrestrial civilizations. In the coming months, two teams of astronomers are going to send messages into space in an attempt to communicate with any intelligent aliens that might be out there listening.

These efforts are like building a big fire in the woods and hoping someone finds you. But some people question whether it is wise to do this at all.

The Pioneer 10 spacecraft carries this board, which depicts basic information about humans and the Earth. Carl Sagan, Frank Drake, Linda Salzman Sagan, NASA Ames Research Center via WikimediaCommons

The history of METI

Early attempts to contact extraterrestrial life resembled notes in a bottle sent by shipwrecked survivors on a deserted island. In 1972, NASA launched the Pioneer 10 spacecraft towards Jupiter carrying a board with a drawing of a man and a woman and symbols showing where the spacecraft came from. In 1977, NASA continued the tradition and provided a gold record that was attached to the Voyager 1 spacecraft.

These spacecraft - as well as their twins, Pioneer 11 and Voyager 2 - have now left the solar system. But in the vastness of space, the chances of anyone finding these or other physical objects are incredibly slim. Electromagnetic radiation is a much more effective beacon.

Astronomers transmitted the first radio message designed for aliens from the Arecibo Observatory (ZL) in Puerto Rico in 1974. The 1 and 0 series were designed to convey simple information about humanity and biology and were sent toward the globular cluster M13. Since M13 is 25,000 Light years, you should not hold your breath and wait for an answer.

In addition to these purposeful attempts to send a message to aliens, rogue signals from television and radio broadcasts have been leaking into space for nearly a century. This ever-expanding bubble of online scumbags has already reached millions of stars. But there's a big difference between a focused transmission of radio waves from a giant telescope and a diffuse leak—the faint signal from a show like "I Love Lucy" fades beneath the background noise of radiation left over from the Big Bang shortly after it leaves the solar system.

Sending new messages

Almost half a century after the message was broadcast via Arecibo, two international teams of astronomers are planning new attempts at alien communication. One uses a new giant radio telescope, and the other chooses a compelling new target.

One of these new messages will be sent from the world's largest radio telescope, in China, during the year 2023. The telescope, with an effective diameter of 500 meters, will transmit a series of radio pulses across a wide area of ​​sky. These on-off pulses are like the 1's and 0's of digital information.

The message is called "The Lighthouse in the Galaxy" and includes prime numbers and mathematical operators, the biochemistry of life, human figures, the location of the Earth and a time stamp. The team sends the message to a group of millions of stars near the center of the Milky Way galaxy, about 10,000 to 20,000 light-years from Earth. While this maximizes the pool of potential aliens, it means that at best it will be tens of thousands of years before Earth gets an answer.

The second attempt only targets a single star, but with the potential for a much faster answer. On October 4, 2022, a team from the Goonhilly Satellite Earth Station in England will transmit a message to the star TRAPPIST-1. This planet has seven planets, three of which are Earth-like worlds in the so-called "life zone" - meaning they can retain liquid water and therefore possibly life. TRAPPIST-1 is only 39 light-years away from us, so it could take up to 78 years for intelligent life to receive the message and send a reply.

Ethical questions

The question of the possibility of alien contact is fraught with ethical questions, and METI is no exception. The first question is: who speaks for the earth? In the absence of international consultation with the public, the decisions about what message to send and where to send it are in the hands of a small group of interested scientists.

But there is also a much deeper question. If you are lost in the forest, finding the nearest culture is of course a good thing. When it comes to whether humanity should send a message to aliens, the answer is much less clear.

Before his death, the iconic physicist Stephen Hawking spoke out about the danger of making contact with high-tech aliens. He claimed that they could be dangerous and if we gave them the location of Earth they could destroy humanity. Others do not see this as an additional risk, since a truly advanced civilization would know of our existence anyway. Russian-Israeli billionaire Yuri Milner offered a million dollars for the best design of a new message and an effective way to deliver it.

As of today, no international regulations govern METI, so the experiments will continue, despite the concerns.

For now, intelligent aliens remain in the realm of science fiction. Books like The Three-Body Problem by Cixin Liu offer grim and thought-provoking perspectives on what success in METI efforts might look like. It doesn't end well for humanity in the books. If humans ever make contact in real life, I hope the aliens come in peace.

For an article in The Conversation

More of the topic in Hayadan:

• Curious children: we are trying to contact aliens - but do they want to contact us?
• In the last twenty years we have discovered a lot of planets, so why haven't we found aliens?
• Who is an alien?
• Question in the Knesset: Have UFOs landed in Israel?