Project 10073 Record Card and Incident Report — 21 May 1959

On May 21, 1959, at approximately 1800Z, a witness identified as a 38-year-old member of the Pennington County Sheriff's Office observed an unidentified aerial object near Rapid City, South Dakota. The witness, who is noted as a trained observer and qualified pilot familiar with weather phenomena and balloons, described the object as a white, oval or elliptical shape, appearing as small as a silver dollar and having a very smooth surface. The object was estimated to be at an altitude of 500 feet and approximately 2.5 miles away from the observer's position. The witness observed the object for 20 seconds as it performed a smooth, positive descent before settling behind a hill. Following the initial sighting, the observer attempted to locate the object by driving to a higher vantage point and later scouting the area in a civilian Cessna aircraft. A member of the 28th Bomb Wing also conducted an aerial search of a 20-mile radius, but no further sightings were reported. The report notes that the sighting occurred within 10 miles of Ellsworth Air Force Base and 4 miles of the Rapid City Municipal Airport, yet no other aircraft were in the vicinity at the time. The official assessment concludes that the description is characteristic of a weather balloon, noting that a balloon had been released from the municipal airport at 1730Z, approximately 3.5 miles north-northeast of the sighting location. The report was submitted in compliance with Air Force Regulation 200-2.