Vicksburg, MississippiApril 1949

On April 24, 1949, four Navy enlisted men conducting weather observations near White Sands Proving Ground, New Mexico spotted a rapidly moving whitish spherical object in the sky. The men were tracking a weather balloon using a theodolite, a precision surveying instrument, when they noticed the unknown object moving eastward at high speed. They estimated its angular motion at about five degrees per second based on their stopwatch and visual estimates. The object appeared to be roughly 22 times longer than it was wide, with a slight yellowish tint on one side, as if shaded from the sun.

The observers had difficulty tracking the object because it moved too quickly for them to keep the theodolite trained on it. After about 60 seconds of observation, the object grew too small to see and disappeared from view. Its bearing stayed relatively constant while its elevation angle first decreased to a minimum before increasing again. Based on the angular measurements and the object's motion, the observers calculated that if it was a balloon at the speeds observed, it would have reached an altitude of roughly 300,000 feet.

However, this conclusion presented a problem. The observers released a second weather balloon 15 minutes later as a control. That balloon climbed to 93,000 feet before bursting, landing only 13 miles south of the observation point. The rapid drift observed in the unknown object could not be explained by normal wind speeds at high altitude, since the second balloon did not move nearly as fast or as far.

The case file includes correspondence between Air Force commands discussing the incident and the challenges of documenting unidentified aerial objects. Consultants noted that accurate distance estimates require knowing what the object actually is. The observers themselves initially believed they were seeing their own released balloon before realizing it was a separate object. The file concludes that without closer examination or additional data, positive identification of the object was not possible.

The full case file is reproduced below as held by the National Archives, 16 pages.