"Hey Bob I'm looking at what Jack was talking about and it's definitely not a particle (Note: “Particle” was a term used by Apollo astronauts to denote something in space other than their own spacecraft) that's nearby. It is a bright object and it's obviously rotating because it's flashing, it's way out in the distance, certainly rotating in a very rhythmic fashion because the flashes come around almost on time. As we look back at the earth it's up at about 11 o'clock, about maybe ten or twelve diame...Earth diameters. I don't know whether that does you any good, but there's something out there."
The piece features a recording of captain Eugene Cernan from the Apollo 17 mission, in which he observes a flashing object from a window of his capsule. It was later surmised that the particle was a discarded rocket stage.
Cernan: “One unique thing about it, Bob, is that it’s got two flashes. As it comes around in rhythmic fashion, you get a very bright flash, and then you get a dull flash. And then it’ll come around with a bright flash, and then a dull flash.”Cernan wasn’t entirely convinced of Schmitt’s convictions however, and later he said:
Schmitt: “That’s the side of the S-IVB and then the engine bell, Gene.”
“Hey, Bob, we got two of those flashers out there. They could be SLA [Spacecraft Lunar Module Adapter] panels. I don’t know. They’re alike in intensity and pretty regular in the bright and dim flashes they come out with, and they’re widely separated.”So, ultimately, it was likely just a piece of the Saturn V rocket or Apollo spacecraft drifting alongside the crew. Buzz Aldrin noticed something similar on the Apollo 11 mission, which he was later wildly misquoted on.