Cast your mind back to December 1968. Apollo 8 was on the launchpad. No human being had ever been beyond Earth orbit. No astronaut had flown on the Saturn V launch vehicle before. There had been no less than three engine failures on the unmanned Apollo 6 mission earlier that year. Apollo 8 had been planned as a low Earth orbit mission to test the Lunar Module but the LM wasn’t ready and, to meet the deadline of sending a man to the moon by the end of the decade, NASA had fundamentally redefined the mission’s objectives. If all went well Apollo 8 would take three men into orbit around the moon and bring them safely back to Earth. There had never been a more risky mission.

To make matters worse the flight programme required the Command/Service Module carrying the astronauts to fly behind the moon where it would be out of contact with Mission Control when it carried out Lunar Orbit Insertion, the crucial manoeuvre that would put the module and its crew into orbit around the moon. If the engines failed the capsule would fly out past the moon and into space. If the burn lasted too long they would plummet down and crash onto the surface of the moon.

Apollo 8 was launched at 12:51 UTC on 21st December 1968. 68 hours and 58 minutes later the orbiter capsule went behind the moon and Mission Control announced loss of signal. For the crew in their “tin can”, the technicians in the control room and millions of members of the public it was a time of almost unbearable tension. For those on the ground there was nothing to do but wait and hope.

PSB (J. Willgoose, Esq. and Wrigglesworth)

To commemorate this temporal void Public Service Broadcasting took recordings of the radio conversations between the Apollo 8 astronauts and Mission Control, added some electronic sounds and created a music track called The Other Side. They didn’t have to work too hard to capture the atmosphere in the control room – the tension is all there in the voice recordings.

Apollo 8, Houston, one minute to LOS. All systems go.

Houston, Apollo 8, 10 seconds to go, you’re go all the way.

Apollo 8, Houston, roger. Thanks a lot, troops. See you on the other side.

In real time there was then a 45 minute gap. On the album track this is compressed to around 10 seconds but the complete absence of voice radio traffic makes the soft thrumming of synth rhythms sound like a ticking grandfather clock in a dark and otherwise silent room. Tick, tock. Are they all right up there? Tick, tock. How can silence be so loud? Tick, tock, tick …

We’re standing by …

Apollo 8, Apollo 8, this is Houston, Houston, over.

Roger Houston, we read you loud and clear. How do you read us?

And with that message from the Apollo 8 commander there is an audible sigh of relief from the flight controllers, the synthesisers swell, joyful guitar playing celebrates success and the music reaches a crescendo. It all works beautifully. Crotchety Man salutes the way Pubic Service Broadcasting have made some excellent music from an extended period of silent waiting.

The Apollo 8 mission was the first time a human had seen the full round Earth from space, the first time human eyes had seen the far side of the moon and the first time an astronaut could see the Earth rising above the horizon of the moon. The image at the top of this post is part of the Earthrise photo taken by Will Anders, the Lunar Module Pilot on Apollo 8. That picture is believed to have inspired the first celebration of Earth Day in 1970. Nature photographer Galen Rowell called it “the most influential environmental photograph ever taken”. That is something well worth commemorating and Public Service Broadcasting have given us a fitting memorial.