Neil Armstrong made "one giant leap for mankind" with a small step onto the moon.
He commanded the historic landing of the Apollo 11 spacecraft on the moon July 20, 1969, capping the most daring of the 20th century's scientific expeditions and becoming the first man to walk on the moon.
His first words after the feat are etched in history books and the memories of the spellbound millions who heard them in a live broadcast.
"That's one small step for man, one giant leap for mankind," Armstrong said. He insisted later that he had said "a'' before man, but said he, too, couldn't hear it in the version that went to the world.
Armstrong, who had bypass surgery earlier this month, died Saturday at age 82 from what his family said were complications of heart procedures. His family didn't say where he died; he had lived in suburban Cincinnati.
He was "a reluctant American hero who always believed he was just doing his job," his family said in a statement.
The moonwalk marked America's victory in the Cold War space race that began Oct. 4, 1957, with the launch of the Soviet Union's Sputnik 1, a 184-pound satellite that sent shock waves around the world. The accomplishment fulfilled a commitment President John F. Kennedy made for the nation to put a man on the moon before the end of 1960s.
Armstrong and Buzz Aldrin spent nearly three hours walking on the lunar surface, collecting samples, conducting experiments and taking photographs.
"The sights were simply magnificent, beyond any visual experience that I had ever been exposed to," Armstrong once said.
In those first few moments on the moon, Armstrong stopped in what he called "a tender moment" and left a patch to commemorate NASA astronauts and Soviet cosmonauts who had died in action.
Although he had been a Navy fighter pilot, a test pilot for NASA's forerunner and an astronaut, the modest Armstrong never allowed himself to be caught up in the celebrity and glamour of the space program.
"I am, and ever will be, a white socks, pocket protector, nerdy engineer," he said in 2000 in one of his rare public appearances. "And I take a substantial amount of pride in the accomplishments of my profession."
Rice University historian Douglas Brinkley, who interviewed Armstrong for NASA's oral history project, said Armstrong fit every requirement the space agency needed for the first man to walk on moon, especially because of his engineering skills and the way he handled celebrity by shunning it.
"I think his genius was in his reclusiveness," said Brinkley. "He was the ultimate hero in an era of corruptible men."
Fellow Ohioan and astronaut John Glenn, one of Armstrong's closest friends, recalled Saturday how Armstrong was on low fuel when he finally brought the lunar module Eagle down on the Sea of Tranquility.
"That showed a dedication to what he was doing that was admirable," Glenn said.
A man who kept away from cameras, Armstrong went public in 2010 with his concerns about President Barack Obama's space policy that shifted attention away from a return to the moon and emphasized private companies developing spaceships. He testified before Congress, and in an email to The Associated Press, Armstrong said he had "substantial reservations."
Along with more than two dozen Apollo-era veterans, he signed a letter calling the plan a "misguided proposal that forces NASA out of human space operations for the foreseeable future."
Armstrong was among the greatest of American heroes, Obama said in a statement.
"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," Obama said.
Obama's Republican opponent Mitt Romney echoed those sentiments, calling Armstrong an American hero whose passion for space, science and discovery will inspire him for the rest of his life.
"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," Romney said.
Armstrong's moonwalk capped a series of accomplishments that included piloting the X-15 rocket plane and making the first space docking during the Gemini 8 mission, which included a successful emergency splashdown.
In the years afterward, Armstrong retreated to the quiet of the classroom and his southwestern Ohio farm. In an Australian interview earlier this year, Armstrong acknowledged that "now and then I miss the excitement about being in the cockpit of an airplane and doing new things."
Glenn, who went through jungle training in Panama with Armstrong as part of the astronaut program, described him as "exceptionally brilliant" with technical matters but "rather retiring, doesn't like to be thrust into the limelight much."
The 1969 landing met an audacious deadline that President Kennedy had set in May 1961, shortly after Alan Shepard became the first American in space with a 15-minute suborbital flight. (Soviet cosmonaut Yuri A. Gagarin had orbited the Earth and beaten the U.S. into space the previous month.)
"I believe this nation should commit itself to achieving the goal, before the decade is out, of landing a man on the moon and returning him safely to Earth," Kennedy had said. "No single space project in this period will be more impressive to mankind, or more important to the long-range exploration of space; and none will be so difficult or expensive to accomplish."
The end-of-decade goal was met with more than five months to spare. "Houston: Tranquility Base here," Armstrong radioed after the spacecraft settled onto the moon. "The Eagle has landed."
"Roger, Tranquility," Apollo astronaut Charles Duke radioed back from Mission Control. "We copy you on the ground. You've got a bunch of guys about to turn blue. We're breathing again. Thanks a lot."
The third astronaut on the mission, Michael Collins, circled the moon in the mother ship Columbia 60 miles overhead while Armstrong and Aldrin went to the moon's surface.
"He was the best, and I will miss him terribly," Collins said through NASA.
In all, 12 American astronauts walked on the moon before the last moon mission in 1972.
Armstrong was born Aug. 5, 1930, on a farm near Wapakoneta in western Ohio. He took his first airplane ride at age 6 and developed a fascination with aviation that prompted him to build model airplanes and conduct experiments in a homemade wind tunnel.
As a boy, he worked at a pharmacy and took flying lessons. He was licensed to fly at 16, before he got his driver's license.
Armstrong enrolled in Purdue University to study aeronautical engineering but was called to duty with the U.S. Navy in 1949 and flew 78 combat missions in Korea.
After the war, Armstrong finished his degree from Purdue and later earned a master's degree in aerospace engineering from the University of Southern California. He became a test pilot with what evolved into the National Aeronautics and Space Administration, flying more than 200 kinds of aircraft from gliders to jets.
Armstrong was accepted into NASA's second astronaut class in 1962 — the first, including Glenn, was chosen in 1959. He commanded the Gemini 8 mission in 1966, bringing back the capsule back in an emergency landing in the Pacific Ocean when a wildly firing thruster kicked it out of orbit.
Aldrin said he and Armstrong were not prone to free exchanges of sentiment.
"But there was that moment on the moon, a brief moment, in which we sort of looked at each other and slapped each other on the shoulder ... and said, 'We made it. Good show,' or something like that," Aldrin said.
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.
Armstrong, Aldrin and Collins were given ticker tape parades in New York, Chicago and Los Angeles and later made a 22-nation world tour. A homecoming in Wapakoneta drew 50,000 people to the city of 9,000.
In 1970, Armstrong was appointed deputy associate administrator for aeronautics at NASA but left the following year to teach aerospace engineering at the University of Cincinnati.
He remained there until 1979 and during that time bought a 310-acre farm near Lebanon, where he raised cattle and corn. He stayed out of public view, accepting few requests for interviews or speeches.
In 2000, when he agreed to announce the top 20 engineering achievements of the 20th Century as voted by the National Academy of Engineering, Armstrong mentioned one disappointment relating to his moonwalk.
"I can honestly say — and it's a big surprise to me — that I have never had a dream about being on the moon," he said.
From 1982 to 1992, Armstrong was chairman of Charlottesville, Virginia-based Computing Technologies for Aviation Inc., a company that supplies computer information management systems for business aircraft.
He then became chairman of AIL Systems Inc., an electronic systems company in Deer Park, New York.
Armstrong married Carol Knight in 1999, and the couple lived in Indian Hill, a Cincinnati suburb. He had two adult sons from a previous marriage.
Armstrong's is the second death in a month of one of NASA's most visible, history-making astronauts. Sally Ride, the first American woman in space, died of pancreatic cancer on July 23 at age 61.
Just prior to the 50th anniversary of Glenn's orbital flight this past February, Armstrong offered high praise to the elder astronaut. Noted Armstrong in an email: "I am hoping I will be 'in his shoes' and have as much success in longevity as he has demonstrated." Glenn is 91.
For anyone else who wanted to remember him, his family's statement made 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."
Borenstein reported from Washington. Associated Press writer Steve Peoples in New Hampshire and AP Science Writers Alicia Chang in Los Angeles and Marcia Dunn in Cape Canaveral, Fla., contributed to this report.