Politicians and scientists react to the news that US astronaut Neil Armstrong - the first man to set foot on the Moon - has died at the age of 82.
Buzz Aldrin, fellow member of the Apollo 11 mission and the second man on the Moon
I was fortunate enough to be one of those crew members and to fly with an outstanding test pilot Neil Armstrong and accompany him in the Lunar Module Eagle, so it's very sad indeed that we're not able to be together as a crew on the 50th anniversary which I have been looking forward to that in 2019.
And I think the entire space, aerospace world will be very saddened to hear this news today - we're missing a great spokesman and leader in the space programme.
Michael Collins, the Apollo 11's command module pilot
He was the best and I will miss him terribly.
US President Barack Obama
Neil was among the greatest of American heroes - not just of his time, but of all time. When he and his fellow crew members lifted off aboard Apollo 11 in 1969, they carried with them the aspirations of an entire nation.
They set out to show the world that the American spirit can see beyond what seems unimaginable - that with enough drive and ingenuity, anything is possible. And when Neil stepped foot on the surface of the Moon for the first time, he delivered a moment of human achievement that will never be forgotten.
Today, Neil's spirit of discovery lives on in all the men and women who have devoted their lives to exploring the unknown - including those who are ensuring that we reach higher and go further in space.
That legacy will endure - sparked by a man who taught us the enormous power of one small step.
Nasa chief Charles Bolden
As long as there are history books, Neil Armstrong will be included in them, remembered for taking humankind's first small step on a world beyond our own.
Besides being one of America's greatest explorers, Neil carried himself with a grace and humility that was an example to us all.
As we enter this next era of space exploration, we do so standing on the shoulders of Neil Armstrong. We mourn the passing of a friend, fellow astronaut and true American hero.
Mitt Romney, US Republican presidential contender
Neil Armstrong today takes his place in the hall of heroes. With courage unmeasured and unbounded love for his country, he walked where man had never walked before.
The Moon will miss its first son of Earth.
I met and spoke with Neil Armstrong just a few weeks ago - his passion for space, science and discovery, and his devotion to America will inspire me through my lifetime.
Bill Nelson, US senator and former astronaut
Neil Armstrong understood that we should reach beyond the stars. His "one giant leap for mankind" was taken by a giant of a man.
US Defence Secretary Leon Panetta
I was deeply saddened to learn today of the passing of Neil Armstrong, one of America's greatest heroes and Naval aviators.
We are bidding farewell to one of our own. As a decorated Korean War veteran, as an astronaut for Nasa, and as the first man to walk on the Moon, Neil inspired generations of Americans to believe that as a nation we are capable of achieving greatness that only comes with determination, perseverance, and hard work.
As a true pioneer, his one small step showed all mankind the great feats we can accomplish when we set ourselves to the task.
While Neil is no longer with us, his spirit and his legacy of American achievement and national pride will live forever.
John Glenn, former US astronaut and senator
He was willing to dare greatly for his country and he was proud to do that and yet remained the same humble person he'd always been. He was a good friend and he'll be missed.