Campaigne's Messages from Outer Space: An NSA Puzzle and Its Key
In 1966, NSA's Howard Campaigne published a set of invented 'radio messages from outer space' as a cryptanalysis puzzle. In 1969 he printed the key, which shows how arithmetic, logic and set theory could be learned from unknown symbols.
What this record is
This page covers two National Archives items from the NSA series. Both are unclassified articles by Howard H. Campaigne in the NSA Technical Journal, the agency’s internal professional journal. The first is “Extraterrestrial Intelligence” (Volume XI, Number 2), a two-page scan of the puzzle messages (catalog 596347915). The second is “Key to the Extraterrestrial Messages” (Volume XIV, Number 1), an 11-page solution (catalog 596347931). The catalog dates them 1 January 1966 and 31 December 1969. These look like year-only placeholders, not publication dates. Both copies carry an NSA stamp approving release in October 2004 under FOIA case 41472.
What it says
The 1966 article opens with an editor’s note. In the previous issue, Lambros Callimahos had “discussed certain aspects of extraterrestrial intelligence and included several messages to test the reader’s ingenuity”; here, “Dr. H. H. Campaigne offers additional communications from outer space.” The story is kept deliberately simple. A series of radio messages was heard, broken by pauses into repeating units. The different signal combinations have been written as letters of the alphabet and the messages numbered. What follows is essentially a page of letter strings. The first message is the full inventory of symbols. The second pairs runs of A with single letters, and later messages combine more and more symbols.
The 1969 article solves the puzzle one message at a time. Its introduction says Campaigne had presented 29 messages in the earlier article and in a special mathematics and engineering issue of the journal, and that the key adds two new ones, numbers 30 and 31. His method is stated at the outset: “At every step in the solution we make a guess at the meaning. Evidence will quickly accumulate to verify or refute this guess.” He argues that two different consistent solutions are very unlikely, except perhaps in the last steps, where the evidence thins.
The solution builds up in layers. The second message shows that B equals AA and C equals AAA, so the letters are the numbers one to seven. L means “is the same as,” and K is addition. M is subtraction, N is zero, O is multiplication and R is exponentiation. With those in place, the messages turn out to be arithmetic statements written in prefix notation, with the operator placed before its two operands. Q proves to mean “the following statement is false,” so logic arrives next, followed by other truth-value operators. A message reading as 10 equals 8 leads Campaigne to suspect the senders count in base eight. By the final messages the notation is being used for set-theory statements, union and intersection, and the construction of the rational numbers, apparently heading toward the real numbers. He also points out a possible garble in one message and an apparent inconsistency in another. He treats these as the sort of noise a real interception would contain.
Context
These articles, together with Callimahos’s paper (covered here), show the “inverse cryptography” idea put into practice. The idea was a message designed to be learned from nothing, starting with counting. They have nothing to do with UFO reports as such. They are in NSA’s UFO holdings because they concern extraterrestrial intelligence. As exercises they resemble the self-teaching message designs that radio astronomers were proposing in the same years. They show that some of NSA’s senior mathematicians took the problem of reading an alien signal seriously enough to publish on it for colleagues.
Status
Published unclassified puzzle articles, with no connection to any real signal. NSA released them in 2004, and they reached the National Archives as part of the agency’s 2025 UAP transfer.
Sources
- National Archives catalog entry, “Extraterrestrial Intelligence”: https://catalog.archives.gov/id/596347915
- PDF of that record: https://catalog.archives.gov/medialz/electronic-records/rg-615/580103959/457UAP00015_released.pdf
- National Archives catalog entry, “Key to the Extraterrestrial Messages”: https://catalog.archives.gov/id/596347931
- PDF of that record: https://catalog.archives.gov/medialz/electronic-records/rg-615/580103959/457UAP00023_released.pdf
- Series: Records from the National Security Agency Relating to Unidentified Anomalous Phenomena: https://catalog.archives.gov/id/580103959