A Brief-ish History of METI. Part II: From Interplanetary to Interstellar

Historical Evolution of SETI and METI

The second half of the 20th century witnessed a profound shift in how humanity approached the search for cosmic companionship. The Search for Extraterrestrial Intelligence (SETI) expanded dramatically during this era, alongside parallel advances in Messaging Extraterrestrial Intelligence (METI). Researchers transitioned from localized concepts toward actively engaging with interstellar space.

Project Ozma and the Arecibo Message

Among the most pivotal milestones of this period were the first true interstellar SETI and METI experiments. Project Ozma marked the first modern attempt to scan nearby star systems for artificial radio signals. Complementing this passive search was the transmission of the Arecibo Message, representing humanity's first intentional interstellar radio broadcast.

Scientific Legacy of Interstellar Communication

The groundwork laid by Project Ozma and the Arecibo Message shaped the methodology of modern extraterrestrial intelligence research. These foundational initiatives established a scientific framework for interstellar communication that continues to guide contemporary astronomical search strategies.