John Herschel Glenn Jr. (1921–2016) was a U.S. Marine Corps aviator and test pilot, one of the seven original Mercury astronauts, and on February 20, 1962, the first American to orbit Earth. He later represented Ohio in the U.S. Senate for nearly 25 years and, in 1998, became the oldest person to fly in orbit. His place in the UAP record comes from the luminous "fireflies" he reported outside his capsule on that first orbital flight, an episode that the 2026 government file releases brought back into circulation.

Born in Cambridge, Ohio, on July 18, 1921, Glenn married Annie Castor in 1943 and flew 57 combat missions in the Marshall Islands area during World War II. In Korea he flew 63 missions with a Marine squadron and 27 with the Air Force in F-86 jets, shooting down three MiG-15s, and his career brought him six Distinguished Flying Crosses. On July 16, 1957, in a flight called Project Bullet, he made the first supersonic flight across the United States, in 3 hours, 23 minutes and 8.3 seconds. NASA announced him as one of its first seven astronauts on April 9, 1959.

Friendship 7 circled Earth three times in 4 hours, 55 minutes and 23 seconds. At his first orbital sunrise, over Canton Island in the Pacific, Glenn radioed that he was seeing "little specks, brilliant specks" drifting around the capsule, glowing "like little stars," and he named them fireflies. Three months later, on Aurora 7, Scott Carpenter saw the same swarms, knocked his hand against the cabin wall and shook more loose, identifying them as ice particles coming off the spacecraft. Franklin Roach, reviewing astronaut sightings for the University of Colorado UFO study, quoted Glenn's account of a "field of fireflies" and cited the view that the "Glenn effect" was most probably millimeter-size flakes released by the spacecraft at sunrise.

Glenn left NASA in January 1964, worked in business and won a Senate seat in 1974, serving until 1999 and chairing the Governmental Affairs Committee from 1987 to 1995. He ran for the Democratic presidential nomination in 1984, flew on the shuttle Discovery at 77 in October 1998, and received the Presidential Medal of Freedom in 2012. He passed away in Columbus in 2016, at 95.

In May 2026 journalist Sharyl Attkisson shared the full NASA flight recording, writing that NASA had attributed the lights to ice crystals. Weeks later, the second PURSUE tranche, Release 02, included 1963 audio in which Gordon Cooper reports "John's fireflies," with NASA's note that they were frozen condensation separating from the spacecraft. In June, Release 03 added a NASA file of astronaut scientific debriefings on the luminous particles reported by Glenn and Wally Schirra. Glenn is remembered as the first American in orbit and a long-serving senator, and his fireflies stand among the earliest mystery lights reported from orbit and among the first to be explained, traced within months to ice from his own spacecraft.