The moon is a very patient place. It once was a very busy place. Early in its long history, a constant bombardment of space debris left it with great lava bleeds that formed its so-called seas and tattooed it with thousands of craters that endure today. The shooting eventually stopped and the moon fell quiet, and for billions of years it did more or less nothing at all, while the blue-white, watery world just next door bloomed and thrived and exploded with life.
And then, for a tiny blink of time, the moon hosted life too. Over the course of four years, from December 1968 to December 1972, nine crews of human beings orbited and walked on and even drove on the face of the ancient moon. It was remarkable and improbable and, for the 3.5 billion human beings back home, utterly thrilling. But as suddenly as the visits began, they stopped. The humans left and the quiet resumed.
All of that, however, may soon change. For the first time in five decades, the U.S.–along with private-industry and international partners–has committed itself to returning to the moon, and to doing it on a defined timeline. In December 2017, President Trump signed the first of three Space Policy Directives, putting manned lunar exploration back at the top of the NASA agenda. With that, plans that had been in development for a long time took on new urgency. And they are plans that are very different from the way Americans got to the moon the first time.