NASA Administrator Charles Bolden says "as long as there are history books, Neil Armstrong will be included in them."
Bolden issued a statement on Saturday on the famed astronaut's death at age 82. He says Armstrong will be "remembered for taking humankind's first small step on a world beyond our own."
Bolden says Armstrong was "one of America's greatest explorers" who readily accepted President John F. Kennedy's challenge to send an American to the moon.
Armstrong commanded the Apollo 11 spacecraft that landed on the moon on July 20, 1969.
An estimated 600 million people — a fifth of the world's population — watched and listened to the landing, the largest audience for any single event in history.