Cape Canaveral, FloridaApril 1961

On April 11, 1961, experienced radar operators at Cape Canaveral tracked an unidentified flying object on their FPS-8 radar screen for more than 30 minutes. The object appeared as a solid radar blip, similar in size to a C-54 aircraft with no transponder. It was not visible to the naked eye from the ground or from a C-54 range surveillance aircraft that was vectored to within two and a half miles of the target.

The object flew in a series of six or seven narrow, elongated orbits. It traveled at distances ranging from 10 miles to approximately 55 miles from Cape Canaveral, always along an azimuth of 125 to 127 degrees (roughly southeast). The radar operators estimated the object's speed at between 150 and 600 knots. Notably, the object would repeatedly fade from the radar scope at 44 miles on its outbound path and reappear at roughly the same distance on its inbound path, suggesting it was relatively small.

The sighting occurred just before the scheduled launch of Polaris missile test number 1352. A powerful FPS-20 height finder radar (a specialized antenna used to measure the altitude of targets) detected the object only intermittently, picking it up just once every three radar sweeps, and failed to establish the target's altitude. Because the height finder could not track it, an attempted interception by a Guided Control Intercept (GCI) station was called off.

The Air Force investigated whether the object could have been extremely high or extremely low. Analysis ruled out both extremes. The absence of height-finder data and the high speeds recorded made definitive conclusions difficult. The Air Force ruled out Navy operations and found no similar incidents at subsequent missile launches in the area. The Air Force concluded the target was probably real, flying at no more than 35,000 feet, but stated it could not determine why it eluded the height finder radar. The full case file of 39 pages is reproduced below as held by the National Archives.