Project Mogul

Project Mogul was a highly classified 1947 U.S. Army Air Forces program using long "balloon trains" — strings of weather balloons carrying acoustic sensors high into the stratosphere — to listen for the distinctive low-frequency sound signature of Soviet atomic bomb tests, at a time when America had no other reliable way to detect a Soviet nuclear detonation from a distance. Because the program was classified at the highest level, personnel at the Roswell Army Air Field who recovered a downed Mogul balloon array in July 1947 had no idea what they were looking at, and the wreckage's genuinely unusual materials — foil, sticks, and rubberized fabric reinforced with strange internal markings — struck ranch worker Mac Brazel and the soldiers who followed him as strange enough to justify the "flying disc" press release that briefly made international headlines before being walked back the next day as a weather balloon. The U.S. Air Force did not publicly identify Mogul as the true source of the Roswell debris until a 1994 Government Accountability Office review, decades after the fact, once Mogul itself was finally declassified. Mogul remains the mainstream, evidence-supported explanation for the original Roswell debris field, though it explains only the crash-debris claim and not the separately alleged body-recovery stories that emerged in later decades.