The early projects

The United States Air Force began collecting reports of unidentified aerial objects in the late 1940s. Project Sign started in 1948 and was followed by Project Grudge. Both aimed to judge whether the reports might point to a threat to national security.

The work was done in the early Cold War, when officials worried about foreign aircraft as much as about anything unknown, and that context shaped what the investigators looked for.

Project Blue Book

Project Blue Book ran from 1952 to 1969. According to the Air Force’s summary, the project collected well over twelve thousand reports. Most were explained as aircraft, balloons, astronomical objects or other ordinary causes, and about seven hundred remained listed as unidentified.

“Unidentified” in this context means the information available did not allow a confident explanation. It does not mean the investigators concluded that the cause was extraordinary.

The Condon Report

In 1968, a University of Colorado team led by physicist Edward Condon published a study funded by the Air Force. It concluded that further study of such reports was unlikely to add to scientific knowledge. Blue Book was closed in December 1969.

The report was criticized by some researchers who thought certain cases deserved more attention, and defended by others who thought its overall approach was sound. Both reactions are part of the record.

Renewed attention

Public and official interest returned in the 2000s and 2010s. In 2021, the Office of the Director of National Intelligence released a preliminary assessment covering 144 reports from military sources. It said that only one could be explained with high confidence and that limited data made firm conclusions difficult.

In 2022, the Department of Defense established the All-domain Anomaly Resolution Office to coordinate the analysis of such reports, and NASA convened an independent study team that published its findings in 2023, emphasizing the need for better data and open methods.

What the record shows

Across these decades, the common finding is a shortage of reliable data, not a confirmed explanation for the unresolved cases. Many reports come from witnesses who describe what they honestly saw, and many can later be matched to ordinary phenomena once more information is found.

That is why careful documentation matters. A good report notes the time, place, conditions, instruments and independent observers, and it separates the observation from the interpretation. Accounts of unusual experiences are most useful when they are recorded in that way.