Is it time to send another message to intelligent aliens? Some scientists think so.

Scientists have crafted a new message for any intelligent extraterrestrials who might be out there. And they want feedback on whether they should send it. 

The technology needed to send the message is not yet ready. And if and when the note is transmitted, it would take thousands of years for it to reach its destination. In other words, no one expects a return message from ET anytime soon. But the researchers behind the alien memo hope their ideas will open up a dialogue about how to contact aliens and what to say — and how to immortalize humanity as a species. 

"We want to send a message in a bottle in the cosmic ocean, to say, 'Hey, we are here,'" Jonathan Jiang, an astrophysicist at NASA's Jet Propulsion Laboratory (JPL) in California, told Live Science, "even if we are not here some years later."

Related: Why are we still searching for intelligent alien life?

Reaching out to ET 

The message designed by Jiang and his team builds on previous missives that humanity has sent to space; in fact, researchers timed the creation of the new message for the 50th anniversary of the Arecibo message, the first high-power attempt to contact ET. 

That 1974 message used binary code and conveyed information about humanity's base-10 counting system, common important elements and a map of the solar system. The new message, described in a paper published to the preprint database arXiv, also encodes information in binary and describes basic math, physics and biology that aliens would need in order to understand humans, including descriptions of DNA, amino acids and glucose. It would also contain a map of the Milky Way, the solar system and Earth itself, including information about the makeup of the planet and its atmosphere. 

The message is more advanced than its predecessors in several key ways. First, its map of Earth's location in the Milky Way is more precise than the one in the Arecibo message. In that message, scientists tried using the location of rotating stars called pulsars as signposts to pinpoint Earth. But pulsars' positions aren't consistent enough over long periods of time, and these stars aren't easily differentiated from one another in the vastness of the galaxy. Jiang and his team instead used globular star clusters in the Milky Way as landmarks on their proposed map. These spherical huddles of stars are bright and easily visible, and they have enough distinguishing features that they can act as useful signposts. 

The researchers also included a first-of-its-kind time stamp so that any alien intercepting the message would know when it was sent. But how do you convey time to an unknown alien civilization that might have very different ways of measuring than Earthlings do? 

The answer, said message co-designer Qitian Jin of the Hanze University of Applied Sciences in the Netherlands, was in the hydrogen atom. The neutral hydrogen found in interstellar gas can enter a high-energy state after collisions with other atoms or electrons. After about 10 million years, one of these high-energy hydrogens undergoes a transition back to a lower-energy state — an event called a spin-flip transition. This spin-flip transition provides a convenient universal unit of time for communicating how long after the Big Bang the message was sent. 

"I think that is pretty important, for if you see it like a time capsule, when someone receives it, they know when it was sent," Jin told Live Science. "So they can know our history. They can build upon that." 

It might be possible to send multiple messages with updated time stamps and information, Jin added, so that a theoretical alien civilization could learn more about Earth over time. 

Sending and recieving

The search for extraterrestrial intelligence (SETI) can be roughly split into two methods: passive and active. In passive SETI, scientists use massive telescopes to listen or look for hints that intelligent life is out there. Such hints might include radio waves, sent either inadvertently or deliberately by an alien civilization. 

Active SETI involves sending signals. These efforts are far less common, and most so far have been largely symbolic. In 1972 and 1973, the Pioneer spacecraft were launched with a pair of plaques depicting a line drawing of a man and a woman and symbols meant to show where the craft originated. The plaques were the first message from humanity designed to travel outside the solar system, but the chances of them being found in the vastness of space are minuscule. 

In 1977, NASA launched a similar long-shot effort on the Voyager spacecraft, the Golden Record. The record contains music, animal sounds and spoken greetings in 55 languages. It was designed by a committee headed by famous astronomer Carl Sagan and was inspirational to the current team of researchers, said Kristen Fahy, a science systems engineer at JPL and a co-designer of the new message.

"To follow up on that has really been just an honor," Fahy told Live Science. The new message includes a line drawing of a man and a woman similar to those on the Pioneer plaques, but with a more egalitarian spin: While only the man in the 1970s versions was raising his hand in greeting, both the man and the woman are waving hello in the modern illustration. 

The Arecibo message, in contrast to Pioneer and Voyager, was an Earth-based effort. It was sent toward the globular star cluster M13 in 1974 from the Arecibo radio telescope in Puerto Rico, mostly as a symbolic effort. This message is still on its journey to its intended destination; given that M13 is 25,000 light-years away, it's traveled only about 0.2% of the distance it needs to traverse, Jiang and his colleagues wrote in their paper. 

The newly proposed message would be beamed toward a ring of stars about 13,000 light-years from the center of the Milky Way, Jiang told Live Science. This region is thought to contain a number of planets in the habitable zones of their stars, he said. 

"If there are aliens, they are most likely to be there," he said. 

The Arecibo telescope no longer exists; it collapsed in 2020 and then was demolished. The telescopes most likely to transmit the message are the Five-hundred-meter Aperture Spherical radio Telescope in Guizhou, China, also known as the Tianyan telescope, and the Allen Telescope Array in northern California, which was designed to search for extraterrestrial signals. Neither telescope can transmit messages right now — they can only receive them — but transmission abilities could be added in future updates, Jiang said. 

The researchers hope to spark a conversation about what information to send to extraterrestrials and to revive interest in listening for messages. Humans already broadcast radio, television and radar signals into space — a bubble of communications that probably spans about 200 light-years, according to The Planetary Society. That's not very far — but the bubble will continue to grow, and the impression humanity is giving off might not be the best, said Stuart Taylor, an astrophysicist at the SETI Institute who helped craft the new message. 

"It would probably be better, since they're going to listen to us anyway, to send a positive message," Taylor told Live Science. The hope, he said, is that an alien civilization advanced enough to reach for the stars would be highly cooperative — the "bonobos of the galaxy" — and have good advice for Earthlings on how to reconcile our differences, Taylor said, referencing the relatively peaceful primate relative of chimpanzees. 

"We're kind of the chimpanzee 'fighting' civilization," Taylor said. "Some other civilization just may have a basically more peaceful personality, like bonobos do." 

Originally published on Live Science.