It was a time when the word “impossible” did not exist. That’s the way Gene Cernan remembers it. Another astronaut, Walter Cunningham, recalls, “We not only believed that we could fly a new spacecraft that they shipped down here, we thought we could fly the crates they shipped them in.” They’re talking about the heady days of NASA’s Apollo program that put men on the moon, regarded by many as the greatest single achievement of the 20th century and one of the outstanding human endeavors of all time.