Armstrong had undergone heart surgery just a few weeks ago.
In 1969, Armstrong commanded the Apollo 11 spacecraft, the first ever to reach the moon. As he became the first person to walk on the moon, he famously said “one small step for man, one giant leap for mankind” and spent nearly three hours walking on the moon with Edwin “Buzz” Aldrin.
In recent years, he lived with his wife Carol in Ohio and stayed largely out of public view.
Read More: NBC News