Portsmouth, N.H., July 1951July 1951

On the evening of July 24, 1951, a captain and corporal with the U.S. Air Force were driving north on U.S. Route 1 near Portsmouth, New Hampshire, heading toward a toll bridge. At approximately 1910 hours (7:10 p.m.), they saw an unusual object flying over the bridge from east to west at an estimated altitude of 1,000 to 2,000 feet.

The object looked like a long tube with a fin at one end, measuring roughly 100 to 200 feet in length and about one-fifth that distance in thickness. It was grayish to nearly invisible, resembling fused glass. The entire surface was covered with black polka-dotted spots. The object left no exhaust or vapor trail, except for a faint swath that resembled a very weak rainbow. The witnesses heard no sound. The object remained visible for approximately 20 seconds before disappearing suddenly, as though it had entered a cloud bank, though the sky was clear at the time.

The captain, who provided the primary account, estimated the object's speed at 800 to 1,000 miles per hour. The corporal, who also observed the object, stated he could offer little additional detail and deferred to the captain's judgment on height and speed estimates. An investigator noted that the corporal's familiarity with aircraft was minimal. A weather sequence report was requested and filed with the case. The Air Force's official evaluation of the sighting was "probably balloon," though the case record itself labeled the sighting as unidentified.

The full case file, comprised of 9 pages as held by the National Archives, is reproduced below.