In the four decades since the world watched his "one giant leap for mankind", Neil Armstrong hasn't had much use for the limelight.
So as, the first man on the moon celebrates his 80th birthday on Thursday no large party is expected.
Last year, he took part in celebrations for the 30th anniversary of his famous moon landing July 20, 1969, but with seemingly less enthusiasm than his publicity-hungry colleague Buzz Aldrin.
Still, discussions about the future of NASA's manned exploration programme this year after President, Mr Barack Obama, moved to scrap a planned return to the moon again brought the legend before Congress.
Armstrong, who has rarely made public statements since his history-making accomplishment, criticised that the plans abandoned a vision already approved by Congress, without consultation with key stakeholders.
He also signed a letter to Mr Obama along with other Apollo astronauts Eugene Cernan and Jim Lovell, saying the new plan did not provide enough clear details and put the goal too far off, leaving the US "on a long downhill slide to mediocrity".
Born in 1930 in Wapakoneta, Ohio, Armstrong flew in his first plane at age six. At 15 he'd started flying, working odd jobs around his town to pay for lessons at a local airport.
He got a pilot's license before he could drive a car, according to his Nasa biography.
After being called to active duty in the US Navy in 1949, Armstrong flew 78 combat missions during the Korean War, and later worked as an engineer and test pilot.
He became an astronaut in 1962 and flew his first space mission in 1966. His trip to the moon required four years of training, according to Nasa.
His first steps on the lunar surface were shown on live television in homes around the world, immortalising his famous observation, "That's one small step for (a) man, one giant leap for mankind".
Armstrong and his fellow Apollo 11 astronauts, Michael Collins and Aldrin, were embraced as national heroes after their historic moon landing, even receiving the Presidential Medal of Freedom from Richard Nixon. But Armstrong has tried to lead a quiet life.
He retired from space flight after his trip to the moon. He spent a year as a senior Nasa administrator, then taught aerospace engineering until 1979.
For many years he refused to appear in advertisements, and when he became a spokesman for Chrysler in 1979 it was reportedly because he admired their engineering division.
Since then, Armstrong has worked largely in the private sector, serving on the board of Marathon Oil, Learjet and United Airlines, among others.
Numerous American elementary schools are named for the astronaut, and the Neil Armstrong Air and Space Museum opened in Wapokeneta in 1972.
Armstrong, who has been married twice, has two grown children and now lives on a farm in Lebanon, Ohio.