Final Report Concerning Unknown Radar Targets, Atlantic Missile Range, 11 April – 9 May 1961

This document is a comprehensive intelligence assessment and final report from the Aerospace Technical Intelligence Center (ATIC) regarding a series of unidentified radar targets detected at the Atlantic Missile Range between 11 April and 9 May 1961. The primary incident occurred on 11 April 1961, when an unidentified object was tracked by the FPS-8 radar at Cape Canaveral for 30 minutes prior to a Polaris missile launch. The object was estimated to be traveling between 150 and 600 knots and performed 6 or 7 orbits at an altitude estimated to be no more than 35,000 feet. Despite the object being tracked by the FPS-8, the FPS-20 radar at the Patrick AC&W site failed to maintain a consistent track, picking it up only once every three sweeps. Subsequent investigations by ATIC, including contact with Lt/Col James O. Payne of the Air Force Missile Test Center (AFMTC), ruled out Navy operations as the cause. The report details several theories, including the possibility of foreign aircraft surveillance, but ultimately concludes that the targets were likely real, though potentially caused by U-2 aircraft SIF (Selective Identification Feature) equipment or electronic phenomena related to range timing signals. The report notes that subsequent tests involving U-2 aircraft confirmed that their IFF/SIF equipment could produce similar radar returns, which were sometimes misinterpreted as 'second bang' phenomena. The document includes detailed weather data, radar operator reports, and summaries of other radar incidents during the same period, including those involving Polaris, Juno, and Mercury-Redstone tests. The investigation concluded that there was no evidence of hostile foreign aircraft or electronic missions, and recommended continued surveillance of the Atlantic Missile Range.