A documentary on NASA’s lunar mission revealed what the Apollo 11 astronauts were doing inside their spacecraft when their radio temporarily died as they flew across the dark side of the Moon. The revelation was made through previously classified sound recordings of the interactions between the astronauts Neil Armstrong, Buzz Aldrin and Michael Collins.

BBC’s documentary titled “8 Days: To The Moon And Back” focuses on the remarkable achievement of the three astronauts who pioneered NASA’s first human mission to the Moon. Aside from general details about the mission, the program also provides new information that was previously not publicized.

This includes the astronauts’ conversations with one another when their command module passed by the dark side of the Moon as part of the Lunar Orbit Insertion. As they entered the Moon’s orbit and reached its far side, their contact with NASA’s Mission Control on Earth was lost.

During these seemingly tense moments, previously classified recordings revealed that the astronauts were actually admiring the impressive terrain of the Moon’s hemisphere that never faces Earth.

“Look back there behind us, sure looks like a gigantic crater,” Armstrong said in the recording. “Look at the mountains going around it. My gosh, they’re monsters.”

Since the astronauts knew that they were out of radio contact with Mission Control, they were a bit informal in their conversations with one another.

“There’s a big mother over here, too,” Aldrin said while referring to another huge mountain on the lunar surface.

“Come on now, Buzz, don’t refer to them as big mothers,” Collins replied. “Give them some scientific name.”

Back on Earth, members of Mission Control were feeling nervous as they waited for radio contact with Apollo 11 to be reestablished, Express reported. For the duration of the radio silence, which lasted about 47 minutes, NASA was not sure if the mission was still going according to plan or if something bad had happened to the astronauts.

Fortunately, after Earth became visible again from the command module, the astronauts were able to regain contact with Mission Control. Collins, who piloted the module, broke the radio silence by contacting NASA to provide a report on the status of the mission.

apollo 11 training
Neil Armstrong holds a bag while Edwin "Buzz" Aldrin practices scooping up a lunar sample during training. NASA