Green River, UtahFebruary 1948

On February 18, 1948, a bright fireball streaked across the sky in broad daylight over parts of Kansas, Nebraska, Oklahoma, Colorado, and New Mexico. Two B-29 bombers flying southeast of Limon, Colorado at approximately 20,000 feet observed what they described as a huge, multicolored ball of fire trailing a dense cloud of smoke. The explosion was heard across a wide area and created considerable alarm among residents who variously reported it as a falling plane, a jet aircraft, or a fireball.

The Air Force investigation quickly determined that the phenomenon was a meteorite fall, not a weapons test, satellite, or unknown aircraft. This conclusion was supported by optical evidence and meteorite recovery. An amateur photographer named Duane Gray captured striking photographs of the dust trail from a point nine miles north of Norton, Kansas, just four minutes after the explosion occurred. The bluish-white smoke remained visible in the sky for about an hour.

The object was confirmed to be the Norton County meteorite, a rare and scientifically significant specimen. Beginning in late April 1948, search parties organized by the University of New Mexico's Institute of Meteoritics began recovering fragments from a calculated impact zone. The meteorite type, an achondrite, was known to be fragile and prone to rapid deterioration. Recovery efforts eventually yielded hundreds of fragments, including several large stones. The largest specimen, weighing over 100 pounds, was discovered in a clover field where it had buried itself about two feet into the soil. Scientific analysis showed that the meteorite was of exceptional interest to researchers, and specimens were studied at universities and research institutes including the University of Chicago's Institute for Nuclear Studies.

The full case file is reproduced below as held by the National Archives, totaling 63 pages.