Messaging extraterrestrial intelligence grew from 1962 Venus tests to messages aimed at stars, before Earth had a rulebook.

The Story

The Arecibo Message flew before METI had an agreed rulebook; later institutions tried to build one.

Arecibo is best understood as a symbolic demonstration carried out before a formal international framework for METI existed. Later documents distinguish post-detection SETI protocols from rules for sending messages and call for broader consultation. The ordinary institutional reading is therefore straightforward: the broadcast did not rest on a documented global authorization or scientific consensus.

• Protocol gapThe 1974 transmission predates the later proposals specifically designed to decide whether and how humanity should send deliberate messages.
• Limited mandateA ceremonial experiment did not amount to authorization from governments, the United Nations, or the worldwide scientific community.
• Later cautionSubsequent SETI and METI work treats consultation, message design, and international participation as unresolved responsibilities.

• The Arecibo Message was largely ceremonial or experimental, and questions about who could speak for humanity remained unresolved decades later.journals
• A 2011 protocol paper identified the lack of an established METI protocol since Arecibo and proposed constraints on encoding, content, transmission, and repetition.arxiv
• The International Academy of Astronautics proposed an international process for deciding whether and how to communicate with extraterrestrial civilizations.iaaspace