While Apollo 10 is now often overlooked as the “dress rehearsal” mission to Apollo 11’s successful lunar landing later in 1969.  However, during the mission’s one hour passage round the far side of the moon when no radio signals can be received – at least not from Earth, the mission’s astronauts John Young, Gene Cernan and Thomas Stafford heard some strange sounds.

Apollo 10's command module which orbited the Moon returned to Earth and is now on display in London's Science Museum. Courtesy: Seradata/David Todd

Apollo 10’s command module which orbited the Moon returned to Earth and is now on display in London’s Science Museum. Courtesy: Seradata/David Todd

Recordings and transcripts from the one hour period behind the moon have the astronauts hearing strange whoosh-ing in their headsets and the Apollo 10 astronauts comment on it as sounding like “outer space type music”.  NASA believes that the strange sounds were due to internal radio interference.  By the way, the “Dark Side of the Moon” is, of course, the seminal album of Pink Floyd, but this title is purely coincidental.