Did Mercury Seven astronaut John Glenn see fireflies while orbiting Earth? It's one of the most jovial anecdotes in the history of NASA's space program and its origins date all the way back to the first successful manned spaceflight to orbit Earth. While going around the Earth, Glenn began reporting weird visions beyond his window. He described them as mysterious, brilliantly-hued particles flying all around his capsule.
NASA was immediately concerned as they listened to Glenn's report from space. After all, space was an even newer frontier in 1962 than it is now, and NASA didn't have all the answers right away. The scientists back on Earth worried that perhaps Glenn's spacecraft, Friendship 7, was disintegrating in space - or perhaps that the astronaut was actually losing his mind. Luckily, it was neither of those things and Glenn lived to tell the tale!
What were John Glenn's fireflies? The answer may actually shock and perhaps make you giggle.
When Glenn reported what he was seeing outside his window as he went around the planet, he made the "fireflies" sound quite amazing - and alien. His description of what turned out to be frozen flakes of condensation is the stuff of science fiction. "I’m in a big mass of thousands of very small particles that are brilliantly lit up like they’re luminescent," Glenn told mission control on Canton Island. "They are bright yellowish-green. About the size and intensity of a firefly on a real dark night. I’ve never seen anything like it."
He went on to describe the phenomena:
"They swirl around the capsule and go in front of the window and they’re all brilliantly lighted. They probably average maybe 7 or 8 feet apart, but I can see them all down below me, also. ... They’re very slow; they’re not going away from me more than maybe 3 or 4 miles per hour. They’re going at the same speed I am approximately. They’re only very slightly under my speed. Over. They do, they do have a different motion, though, from me because they swirl around the capsule and then depart back the way I am looking."
At this point, the NASA technicians back on Earth listening to Glenn's report started to worry. Glenn's description of orbiting the planet is probably not what they expected.
NASA, alarmed by Glenn's incredible report from space, became worried that something was wrong with Friendship 7 itself. One theory on the ground was that the spacecraft's heat shield was disintegrating. With the craft reaching speeds of 17,000 miles per hour as it orbited the Earth, NASA feared that Friendship 7 would simply burn out in space without a heat shield. Had this been the case, Glenn would have been the first man to die in space.
NASA also worried that Glenn has perhaps having visions in space as the result of some kind of illness he had contracted while orbiting the planet. After all, this was 1962 and there was still so much human didn't understand about the final frontier. It wasn't uncommon for a person's mind to lean on what it knew from science fiction. Luckily, Glenn wasn't suffering from a space illness or exposure to a big hallucinatory dose of melange.
While hardcore space fans might liken the mysterious fireflies to be some kind of strange phenomena or perhaps an alien life form, the answer is actually more simple: condensation. John Glenn's own sweat and urine vented from Friendship 7 is to blame. Glenn was actually seeing frozen flakes of condensation (space is very cold, after all) floating past him and not space fireflies.
A bummer, but also kind of hilarious, right? Space is just full of mysteries.