Christmas is over, the new year has started, and we're all back at work at the Ars Orbiting HQ. This means that it's time to pick back up with part four of "The Greatest Leap," our retrospective on the Apollo program. The first three parts—which you can find here, here, and here—took us from the start of the program through the triumph of the first lunar landing in 1969; the next part focuses on the people who made things happen.

Though our interviewees came from all different parts of the program—from flight operations to engineering to planning to management to actually flying missions—they all had a similar view of Apollo: it was a singular, supernal experience that affected them profoundly. Although many suffered through personal hardships and sacrifices—even the most stable of marriages were tested by seemingly unending years of overtime and weekend work—no one we spoke to regretted their time on Apollo or saw it as anything other than a profoundly worthwhile effort. In many ways, working on the program was a dream job—the ultimate engineering challenge, with an almost laughably audacious goal, balanced by effectively unlimited funding. It's like that old adage when you have "good," "fast," and "cheap," and you can pick two—for Apollo, "good" and "fast" were the priorities, and "cheap" wasn't even in the picture.

The result, of course, was that humans walked on the Moon. How could any engineer turn that down?

"The Greatest Leap" returns with part four next Tuesday, January 30. Parts five and six will run on subsequent Tuesdays—February 6 and February 13.