Tributes to Neil Armstrong from US President Barack Obama and fellow astronaut Buzz Aldrin are among those pouring in for the first man to walk on the Moon.
Armstrong died Saturday at the age of 82. He underwent a heart-bypass surgery earlier this month, and died from complications just a few days after his birthday.
The American astronaut led the Apollo 11 mission. On July 20, 1969, Armstrong planted his left foot on the moon's surface, and famously said: "That's one small step for a man, one giant leap for mankind."
More from GlobalPost: Neil Armstrong, first man on the moon, dead at 82
President Obama said he and wife Michelle were "deeply saddened to hear about Armstrong's death":
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.
Fellow astronaut Edwin "Buzz" Aldrin told the BBC his colleague was a "very capable commander and leader of a world achievement."
"We're missing a great spokesman and leader in the space program," said Aldrin, a lunar module pilot on Apollo 11.
In a statement on the NASA website, Aldrin said:
Whenever I look at the moon it reminds me of the moment over four decades ago when I realized that even though we were farther away from earth than two humans had ever been, we were not alone. Virtually the entire world took that memorable journey with us. I know I am joined by millions of others in mourning the passing of a true American hero and the best pilot I ever knew.
My friend Neil took the small step but giant leap that changed the world and will forever be remembered as a landmark moment in human history. I had truly hoped that in 2019, we would be standing together along with our colleague Mike Collins to commemorate the 50th Anniversary of our moon landing. Regrettably, this is not to be. Neil will most certainly be there with us in spirit.
NASA chief Charles Bolden also issued a tribute to Armstrong:
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. When President Kennedy challenged the nation to send a human to the moon, Neil Armstrong accepted without reservation.
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.
Armstrong's family described him as "a reluctant American hero who always believed he was just doing his job":
While we mourn the loss of a very good man, we also celebrate his remarkable life and hope that it serves as an example to young people around the world to work hard to make their dreams come true, to be willing to explore and push the limits, and to selflessly serve a cause greater than themselves.
For those who may ask what they can do to honor Neil, we have a simple request. Honor his example of service, accomplishment and modesty, and the next time you walk outside on a clear night and see the moon smiling down at you, think of Neil Armstrong and give him a wink.