Stockton, Calif, January 1951January 1951

On January 1, 1951, a red and green balloon-shaped object descended on the Stockton Naval Supply Depot in Stockton, California. The object exploded when it hit the ground, though part of it burned fiercely until naval security guards extinguished the flames. Investigators recovered the residue and debris.

The recovered materials were sent to the Federal Bureau of Investigation for laboratory examination. Among the debris, investigators found a bamboo ring, which suggested the possibility that the object had tropical or oriental origins. The Air Force also noted that the materials appeared unremarkable, and no fingerprints of value were found on the bamboo ring.

The Air Materiel Command investigated the incident by consulting with personnel who worked on high altitude and weather balloons. They noted that typical weather balloons sometimes carry explosive caps designed to separate equipment at a certain altitude, and that an electrical malfunction could explain the explosion. However, they had no knowledge of bamboo rings being used on any balloons then in use.

The FBI concluded that the object was probably a homemade hot air balloon. The Air Force's official evaluation listed the case as "unknown," though the agencies involved appeared to accept the FBI's assessment. No further action was recommended, and the incident file was closed.

The full case file, comprising 11 pages as held by the National Archives, is reproduced below.