Forgotten astronaut of Apollo 11 made candid admission as he orbited the Moon alone

History's forgotten astronaut, who accompanied Neil Armstrong and Buzz Aldrin to space as man set foot on the Moon for the first time, wrote an eerie message as he waited for his pals.

Yes, 55 years ago yesterday (July 20), NASA sent Apollo 11 to the Moon but there was one person who joined Commander Armstrong and Lunar Module Pilot Aldrin in the space shuttle.

Buzz Aldrin stands beside the American flag as Neil Armstrong snaps the picture. (Bettmann/Getty)

At 8.17pm on July 20, 1969, the iconic duo successfully landed the Apollo Lunar Module Eagle on Earth's only natural satellite, and the two took pictures including footprint on the Moon and Aldrin saluting the US flag.

Armstrong was the first person to stand on the Moon, coining the phrase: "That's one small step for man, one giant leap for mankind."

They would then spend two hours and 36 minutes walking on the surface before taking the Lunar Module to the spacecraft, where Michael Collins was left in isolation.

He was dubbed the 'loneliest man in history' as he orbited the Moon while his colleagues landed on it.

Commander Neil Armstrong, Command Module Pilot Michael Collins and Lunar Module Pilot Buzz Aldrin. ( Space Frontiers/Getty Images)

Collins, who died of cancer at the age of 90 in 2021, only had himself, his thoughts, and a pen and paper - where he made a candid admission saying he was 'sweating like a nervous bride' waiting for his buddies to return.

He wrote: “My secret terror for the last six months has been leaving them on the Moon and returning to Earth alone; now I am within minutes of finding out the truth of the matter.

"If they fail to rise from the surface, or crash back into it, I am not going to commit suicide; I am coming home, forthwith, but I will be a marked man for life and I know it.”

While he said no more on why he thought he would be a marked man for life, it is understood it was because he would be returning without them as if he deserted them - despite him having no control over their return.

Collins was dubbed the 'loneliest man in history' as he waited for his colleagues Armstrong and Aldrin to return from their two-hour-36-minute Moon walk. (Bettmann/Getty)

Later, he went on to write a book about becoming the person furthest away from Earth, titled Carrying the Fire: An Astronaut's Journey.

He wrote: “I am alone now, truly alone, and absolutely isolated from any known life. I am it. If a count were taken, the score would be three billion plus two over on the other side of the Moon, and one plus God knows what on this side.”

Aldrin is the last living man who took to space as part of the Apollo 11 mission, with Armstrong dying at the age of 82 in 2012.

Aldrin, who is now 94, Armstrong and Collins, were all born in 1930.