Project Blue Book Case #1538. On July 22, 1952, an unidentified aerial object was observed over Los Alamos, New Mexico — the birthplace of the atomic bomb and the primary nuclear weapons design laboratory in the United States. Along with Oak Ridge and Hanford, Los Alamos formed the trinity of nuclear sites that had produced the weapons that ended World War II and now formed the backbone of America's nuclear deterrent.
Los Alamos in 1952 was actively designing and testing thermonuclear weapons. The laboratory's scientists were developing the hydrogen bomb — a weapon thousands of times more powerful than the Hiroshima device — under extreme secrecy and urgency. The security apparatus surrounding Los Alamos was among the most intensive in the world, with restricted airspace, ground patrols, and electronic monitoring.
The July 22, 1952, sighting came during the peak of the great wave, the same week as the famous Washington, D.C., radar events. The coincidence of unexplained objects appearing over both the nation's capital and its most sensitive nuclear weapons facility simultaneously was deeply unsettling to military intelligence.
Los Alamos had a history of UFO sightings dating back to at least 1948, when the famous "green fireball" phenomenon began. Astronomer Lincoln La Paz was commissioned to investigate repeated sightings of unusual green luminous objects over the New Mexico nuclear corridor — a phenomenon he could not attribute to conventional meteors.
The July 1952 object could not be identified despite the extensive security monitoring of Los Alamos airspace. The case was classified "Unknown."