Had the historic Apollo 11 mission failed and astronauts Neil Armstrong and Buzz Aldrin couldn't leave the moon's surface, President Richard Nixon had a speech prepared.

Armstrong and Aldrin were the first men in the history of mankind to travel to the moon and walk on the surface. The completed the historic spacewalk on July 20, 1969.

Two days after Apollo 11's launch from the Kennedy Space Center in Florida, Nixon's speech writer wrote a brief speech in the event they never returned to Earth. It was kept hidden until the 30th anniversary of the Apollo mission in 1999.

"Fate has ordained that the men who went to the moon to explore in peace will stay on the moon to rest in peace.

"These brave men, Neil Armstrong and Edwin Aldrin, know that there is no hope for their recovery. But they also know that there is hope for mankind in their sacrifice.

"These two men are laying down their lives in mankind's most noble goal: the search for truth and understanding.

"They will be moured by their families and friends; they will be mourned by their nation; they will be mourned by the people of the world; they will be mourned by a Mother Earth that dared send two of her sons into the unknown.

"In their exploration, they stirred the people of the world to feel as one; in their sacrifice, they bind more tightly the brotherhood of man.

"In the ancient days, men looked at the stars and saw their heroes in the constellations. In modern times, we do much the same, but our heroes are epic men of flesh and blood.

"Others will follow, and surely find their way home. Man's search will not be denied. But these men were the first, and they will remain foremost in our hearts.

"For every human being who looks up at the moon in the nights to come will know that there is some corner of another world that is forever mankind."

Luckily, the mission was a success and the crew splashed down in the Pacific Ocean on July 24, 1969.

Nixon met with the astronauts after their return and said, "This is the greatest week in the history of the world since the creation, because as a result of what happened this week, the world is bigger."

Photos: 50 years ago, NASA put man on the moon