Project Blue Book was yet another program from the U.S. Air Force, following up on Projects Sign and Grudge. The program conducted a series of studies between 1952 and 1969 to figure out if UFOs could hurt national security and to search for UFO data. More than 10,000 of those case files are freely available on the Internet Archive.
According to Encyclopedia Britannica, investigators ultimately collected more than 12,000 sightings and classified them as either “identified” (meaning the events could be explained by astronomical, atmospheric or human phenomena) or “unidentified.” That category made up about 6 percent of the total number of reported cases.
The Condon Committee – 1966-1968
The Condon Committee, more formally known as the University of Colorado UFO Project, was a group funded by the Air Force that looked at UFOs under leadership from physicist Edward Condon. The group re-examined the information from Project Blue Book and published its efforts in the “Scientific Study of Unidentified Flying Objects” (also known as the Condon Report) in 1968.
According to How Stuff Works, the Condon Report found that about one-third of the cases couldn’t be explained, even though the introduction stated that “further extensive study of UFOs probably cannot be justified on the expectation that science will be advanced thereby.”
Some reports say that the ultimate purpose of the report was to stop U.S. investigations into UFOs. Whether or not that was true, Blue Book ceased operations in 1969, the year after the Condon Report was released.