Project Grudge · UFOCosmos

USAF UFO investigation program that succeeded Project Sign with an explicit debunking mandate. Grudge produced a classified report concluding that UFOs posed no threat to national security and were attributable to misidentifications, hoaxes, or psychological phenomena. The program was replaced by Project Blue Book.

Project Grudge was established in February 1949 as the successor to Project Sign. Where Sign had approached UFO reports with genuine investigative intent, Grudge was characterized by a predetermined conclusion: that UFOs did not represent genuine phenomena requiring serious investigation. The Grudge report, released in 1949, attributed virtually all UFO sightings to misidentifications of conventional objects, hysteria, hoaxes, or mental instability. Critics noted that the report dismissed cases without thorough investigation. Captain Edward Ruppelt, who later ran Project Blue Book, wrote in his memoir that Grudge investigators had been instructed to debunk rather than investigate. Despite this, Grudge's own files contained cases that could not be satisfactorily explained by conventional means.