Project Blue Book closes (1969)
The U.S. Air Force ran Project Blue Book, cataloging more than 12,000 UFO reports. A University of Colorado review led the Air Force to shut it down, concluding no sighting threatened national security or showed advanced technology.
The government stepped back from official UFO investigation for decades.
The closure hardened a stigma that discouraged pilots and scientists from reporting sightings.
It set the default posture Isaacman is now breaking: for years the government studied, then dismissed, unexplained objects.
