Once a subject only for science fiction, "conversing with aliens" has begun to be discussed seriously among scientists, thanks to advances in AI. What is the innovative approach that SETI researchers are proposing?

An Age When AI Becomes Humanity's Spokesperson

In 2024, Dr. Franck Marchis of the SETI Institute and Ignacio G. López-Francos of NASA's Ames Research Center proposed the idea of sending a large language model (LLM) into space. The aim is to enable an "indirect conversation" with extraterrestrial intelligence, and it was also featured in Scientific American.

Conventional approaches, like the 1974 Arecibo message, transmitted basic information on math and chemistry, the structure of DNA, and the human form as simple binary code. But with only 1,679 bits of data, there are limits to conveying humanity's complex culture and knowledge.

Dr. Marchis and colleagues' proposal overturns this from the ground up. If an LLM trained on human knowledge is sent into space, a receiving alien civilization could learn our language, ask the AI questions, and come to understand humanity deeply.

Technical Challenges and Solutions

This ambitious plan has several technical hurdles.

First is the problem of data size. Meta's Llama-3-70B is about 130 GB, far too large for interstellar communication. But using a technique called "quantization," it can be compressed to a few GB while maintaining performance.

Next is the challenge of transmission speed. The current communication speed with NASA lunar probes is up to about 100 Mbps, but in interstellar communication it drops to about 100 bits per second. As a result, even a compressed model would take many years to transmit to the nearest star system, Alpha Centauri (about 4 light-years away).

Researchers are also studying faster transmission technologies, such as the development of a high-power laser transmitter proposed by the Breakthrough Initiative, and a "solar focus mission" that uses the Sun as a gravitational lens.

AI Opening a New Era for SETI

In fact, AI is also causing a revolution on the receiving side of SETI (the search for extraterrestrial intelligence).

At the 2025 GTC (GPU Technology Conference), Luigi Cruz of the SETI Institute presented a new method combining NVIDIA GPUs with a neural network. By synchronizing the 42 antennas of the Allen Telescope Array, it succeeded in identifying radio signals from the Crab Nebula's pulsar in real time.

This is not just a technology demonstration. It showed a more effective way for AI to find the "needle" of an intelligent signal in the "haystack of noise from space."

In Japan too, the space venture Spaceshift announced in 2024 a plan to apply AI technology honed in satellite-data analysis to SETI. In cooperation with Professor Keitaro Takahashi of Kumamoto University, an attempt to analyze radio-telescope data from around the world with AI is underway.

Renewing the Post-Detection Protocol

If we really do detect a signal from another world, how should humanity respond?

In October 2025, the International Academy of Astronautics (IAA) SETI Committee released a revised version of the post-detection protocol (the procedures for responding after a signal is detected) for the first time in 15 years. This revision, led by Professor Michael Garrett and others, incorporates new guidelines that take into account the influence of social media and advances in AI.

There are four basic principles:

  • Thoroughly verify a detected signal
  • Do not announce it until it is confirmed
  • Once confirmed, disclose it openly without concealment
  • Do not reply without international consultation

Especially notable is the principle of "not replying on one's own." As Dr. Stephen Hawking warned, caution is required in contact with a civilization that has technology more advanced than humanity's. Dr. Marchis and colleagues' LLM proposal also acknowledges that "there is a risk" on this point, while arguing that it is worth starting the discussion.

A New Search Approach

A research team from Pennsylvania State University and NASA's Jet Propulsion Laboratory made an intriguing proposal in 2025: a search method based on the idea that alien civilizations must also carry out deep-space communication just as earthlings do.

NASA's Deep Space Network (DSN) regularly sends communications toward planets such as Mars. These communications "leak out" along the orbital plane and are detectable if observed from outside. The team proposes assuming alien civilizations do the same, and observing at the moment when exoplanets overlap one another (planet-planet occultation).

Using this method, it may be possible to detect signals from civilizations within 23 light-years, and observations of the TRAPPIST-1 system have already been carried out.

Carrying On the Legacy of Voyager

In 1977, the Voyager probes set off carrying the "Golden Record." It is an analog "time capsule" packed with human culture, including music, images, and greetings in 55 languages.

The LLM transmission that Dr. Marchis and colleagues propose could be called an update of Voyager's legacy for the digital age. Future space missions may come standard with computers carrying an LLM that works even without an internet connection.

In the distant future, when some civilization discovers that spacecraft and activates the AI, they could learn humanity's language and ask questions about our history and culture. Even if humans no longer exist on Earth by then, our knowledge and memory would live on somewhere in the cosmos.

What About in Your Country?

In Japan, researcher Shinya Narusawa of the Nishi-Harima Astronomical Observatory is known as a leading figure in Japanese SETI research and has led international joint observation projects. Now that the romance of searching for aliens has merged with the cutting-edge technology of AI, how do you feel?

In your country, what is the debate around the search for extraterrestrial intelligence and AI-driven space research? If you could send a message to aliens, what would you want to say? Please tell us in the comments.

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