(Reuters) - Armstrong underwent a heart-bypass surgery earlier this month, just two days after his birthday on August 5, to relieve blocked coronary arteries.
As commander of the Apollo 11 mission, Armstrong became the first human to set foot on the moon on July 20, 1969. As he stepped on the dusty surface, Armstrong said: "That's one small step for (a) man, one giant leap for mankind."
Those words endure as one of the best known quotes in the English language.