Every few months, the document crops up on some corner of the Internet. The NSA has a document on its site that seems to confirm that, in 1969, an extraterrestrial transmission came in. The document, labelled "Key to The Extraterrestrial Messages," is a follow-on to two 1966 documents called "Extraterrestrial Intelligence" and "Communications with Extraterrestrial Intelligence."

"Communications" is more an assessment of how we might someday hear from aliens, including the idea of a "neutrino beam" rather than radio signals. It also demonstrates how we might try to reach out to any potential alien intelligence. Author Lambros D. Callimahos, a former U.S. Army codebreaker, suggests that advanced mathematical equations could provide a galactic "Rosetta stone" for future contact.

But the "Key to the Extraterrestrial Messages" assumes that, in three short years, we had already found that contact. It makes reference to the original NSA doc, which states, "Recently a series of radio messages was heard coming from outer space. The transmission was not continuous but was cut by pauses into pieces which could be taken as units, for they were repeated over and over again." The "Key to the Extraterrestrial Messages" was the solution to those problems. [...]
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