Record 251 · September 1965
Communication with Extraterrestrial Intelligence
National Security Agency (NSA) · United States
Ledger illustration of the record — not a scan of the original paper. — Night Ledger illustration of the file
The paper assumes the existence of extraterrestrial intelligence as a reasonable scientific proposition supported by astronomical data and the Drake equation. It discusses methods for detecting signals (such as radio astronomy), the design of messages that could be universally understood, and the immense difficulties in establishing two-way communication across interstellar distances due to time lags, language barriers, and the need for shared mathematical or scientific concepts. It treats the topic as a serious but speculative scientific and technical exercise rather than asserting any confirmed contact, recovered craft, or biological entities. The document was later included in NSA's UAP records collection released to the National Archives.
Public file: National Archives Catalog / NSA
