When Apollo 10 astronauts made their way around the far side of the moon, there was a point in which they lost total radio communication with Earth. Tapes recorded and transcribed by NASA after the 1969 mission were buried deep into the archives until 2008. When they were unearthed, it seems that during that hour where Apollo 10 was out of contact with Houston, they heard space music.

Maybe when you hear it, you’ll think: that ain’t music. It’s definitely no Pink Floyd Dark Side of the Moon, but whatever it is, it’s weird. Tonight at 10 p.m., a sneak preview of the new season of NASA’s Unexplained Files on the Science Channel explores this spooky phenomenon. In the show’s preview, one astronaut on tape says, “The music even sounds outer spacey, doesn’t it? You hear that? That whistling sound? Whooooooooo!”

After, they debate telling their superiors on land about this strange instance, the reason being, if their sanity was questioned, they’d be grounded for good.

Apollo 15 command module pilot Al Worden observes, “NASA would withhold information from the public if they thought it was in the public’s best interest.”

He asks the Huffington Post, “If you’re behind the moon and hear some weird noise on your radio, and you know you’re blocked from the Earth, then what could you possibly think? … We’d had a lot of incidents where guys who flew in space saw and heard things that they didn’t recognize, and you wonder about all of that.” He says on the promo that if he’d heard it, it would have freaked him out.

Then, in 2005, the Cassini spacecraft picked up similar odd sounds around Saturn. Those were caused by particles moving through the planet’s magnetic field. But the moon has neither an atmosphere nor magnetic field. Someone comes to the conclusion that it’s just the two radios interfering with each other. But Worden doesn’t think it’s that simple, and so the mystery remains.

NASA’s Unexplained Files starts up again on the Science Channel on February 23.

Photos via By: Dan Kitwood/Getty Images