Book excerpt: On July 20, 1969, the world stood still to watch American astronaut Neil A. Armstrong become the first person ever to step on the surface of another heavenly body. Upon his return to Earth, Armstrong was celebrated for his monumental achievement. He was also--as NASA historian Hansen reveals in this authorized biography--misunderstood. Armstrong's accomplishments as an engineer, a test pilot, and an astronaut have long been a matter of record, but Hansen's access to private documents and unpublished sources and his interviews with more than 125 subjects (including more than fifty hours with Armstrong himself) yield the first in-depth analysis of this elusive, reluctant hero.