NASA Administrator Jared Isaacman announced on Tuesday that his agency is rapidly progressing toward building a $20 billion base on the moon, instead of a space station that would orbit the lunar body.At a daylong event, the NASA chief said the Trump administration’s priority for its national space policy is to “never again give up” the moon as the United States races China to establish a presence there first. In accordance with that vision, Isaacman said a U.S.-flagged moon base is necessary to establish a lasting presence in space and will serve as a launching pad for other missions to...