<span class="caption">Scientists think there are 300 million habitable planets in the Milky Way, and some may be home to intelligent life.</span> <span class="attribution">Bruno Gilli/ESO, CC BY</span>
Scientists think there are 300 million habitable planets in the Milky Way, and some may be home to intelligent life. Bruno Gilli/ESO, CC BY

There are two options if a person is lost in the wilderness. They can search for civilization, or they can make themselves easy to spot by building a fire or writing HELP in big letters. The options for scientists interested in the question of intelligent aliens are the same.

Astronomers have been looking for signals from other civilizations in the search for SETI for over 70 years. Most scientists believe that there is life on many of the 300 million planets in the universe. Some life forms may have developed intelligence and technology. The Great Silence is a mystery that has never been solved.

SETI has long been a part of mainstream science, but METI has been less common.

I am a professor of astronomy and have written extensively about the search for life in the universe. I serve on the advisory council for a nonprofit research organization that designs messages to send to extraterrestrial civilizations.

In the coming months, two teams of astronomy are going to send messages into space in an attempt to communicate with intelligent aliens.

These efforts are similar to building a big bonfire in the woods and hoping someone finds you. Some people are wondering if it is wise to do this.

The history of METI

There were quixotic messages in a bottle when attempts were made to contact life off Earth.

The Pioneer 10 craft carried a plaque with a line drawing of a man and a woman and symbols to show where it came from. The Golden Record was attached to the Voyager 1 spacecraft.

The solar system has now all been left by these spaceships and their twins. The odds of physical objects being found in space are minuscule.

It's a much more effective beacon if it's radiation.

The first radio message designed for alien ears was beamed in 1974. The series of 1s and 0s was sent to the M13 to convey information about humanity and biology. You shouldn't hold your breath for a reply since M13 is 25,000 light-years away.

For nearly a century, stray signals from television and radio broadcasts have been leaking into space. Millions of stars have already been reached by this bubble of earthly babble. There is a big difference between a focused blast of radio waves from a giant telescope and a weak signal from a show like I Love Lucy.

Sending new messages

Two international teams of astronomy are planning new attempts at alien communication, nearly half a century after the Arecibo message. One is using a new radio telescope and the other is choosing a new target.

One of the new messages will be sent from the world's largest radio telescope in China. The telescope will beam radio waves over a wide swath of sky. The 1s and 0s of digital information are what these on-off pulse are.

The message is called " The beacon in the sky" and includes prime numbers and mathematical operators, the location of the Earth and a time stamp. The team is sending a message to a group of millions of stars in the center of the Milky Way. It will be tens of thousands of years before Earth will get a reply to the pool of potential aliens.

There is a chance for a much quicker reply if the other attempt is successful. On October 4, 2022, a team from the Goonhilly Satellite Earth Station in England will send a message to the star TRAPPIST-1. The star has seven planets, three of which are Earth-like worlds in thelocks zone, meaning they could be home to liquid and possibly life. It could take as little as 78 years for intelligent life to receive the message from TRAPPIST-1, which is 39 light-years away.

Ethical questions

The prospect of alien contact is ripe for ethical questions, and METI is no exception.

Who speaks for Earth? In the absence of an international consultation with the public, decisions about what message to send and where to send it are in the hands of a small group of scientists.

There is a bigger question. Getting found is a good thing if you are lost in the woods. It's not clear whether humanity should be broadcasting a message to aliens.

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Stephen Hawking was against contact with aliens with superior technology. He argued that if they were given Earth's location, it would destroy humanity. Others don't see any risk since a truly advanced civilization already knows of our existence. There is interest. A Russian-Israeli billionaire has offered $1 million for the best design of a new message.

Despite concerns, the experiments will continue because no international regulations govern METI.

For now, intelligent aliens are in science fiction. The success of METI efforts can be seen in books like The Three-Body Problem by Cixin Liu. In the books, it doesn't end well for humanity. I hope aliens come in peace if humans ever make contact in real life.

The Conversation is a news site dedicated to sharing ideas from academic experts. Chris Impey is from the University of Arizona.

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