"Houston… Tranquility Base here… the Eagle has landed." And with those words, mankind changed forever. We were no longer bound to one planet, one place, troglodytes adhering to the surface of Earth. We became a space-dwelling species. Future historians will divide humanity’s time on Earth into two eras, and the demarcation between them was that moment. Five more times we’d go to the Moon. The next four decades were spent in low-Earth orbit, limited circles ...