Near the end of his address last night, the president made a reference to space travel, saying — quote — "American footprints on distant worlds are not too big a dream."

　　It was only a line. But whenever a president speaks on the subject, the space community is closely trying to read the tea leaves. The sentence leaves a lot to interpretation, but all signs seem to indicate there is renewed focus inside the Trump administration, NASA and the private sector on travel to the moon, sooner than you might think.

　　Our science correspondent, Miles O'Brien, is here.

　　So, Miles, why the moon after all these years?

　　MILES O'BRIEN: Aside from the "because it's there" answer, it's actually a good destination to go and learn about living and working on an encampment in space.

　　You know, we went to the moon 50 years ago now. We left some footprints and flags behind, but we didn't really learn how to live there on a sustained basis. So, while NASA would still like to go to Mars, there's a lot of things you can learn about by setting up an encampment on the moon.

　　And we have learned in the past 50 years there's a lot of water ice on the moon. What is water? Hydrogen and oxygen. What is rocket fuel? Hydrogen and oxygen. So you can learn a lot about how to create rocket fuel on location and perhaps push deeper into space.

　　JUDY WOODRUFF: So this didn't just spring up as an idea because they couldn't think of anything else?

　　MILES O'BRIEN: Well, there was one other factor. There was a mission planned at the end of '18 for the Space Launch System, which is the next heavy lift that NASA is working — heavy lift rocket.

　　One piece of it wasn't going to be ready, built by the Europeans, a service module. And so NASA was faced with the possibility of delaying that mission, an unmanned mission, even later, or maybe doing something like we did with Apollo 8, something bold.

　　In the case of Apollo 8, the lunar module wasn't ready. And we decided to go around the moon. In this case, they're thinking about putting astronauts on this flight maybe early '19, and send them around the moon Apollo 8-style.

　　So, a lot of things have lined up. And, all of a sudden, there is wide agreement in the space community, this might be the next step.

　　JUDY WOODRUFF: And you were telling me, Miles, there's a private sector piece in all of this, Elon Musk announcing just the other day that two individuals, I guess, with some extra spending money …

　　MILES O'BRIEN: To say the least.

　　JUDY WOODRUFF: … have told him they want to go around the moon and come back to Earth.

　　MILES O'BRIEN: Yes.

　　He got a lot of attention for that. He doesn't have a rocket to do it yet. It's just a design right now. It's called the Falcon Heavy, which would have almost the thrust of the mighty Saturn 5 of Apollo days.

　　It will fly for the first time, he hopes, by the summer. So saying there are going to be paying passengers on there by '18 is optimistic, for sure. So, we will watch that with skepticism.

　　But to the extent that the private sector and the government space enterprise sort of push each other toward this destination, a lot of space people are pretty excited about it.

　　特朗普执政期间 人类登月计划有望重启

　　JUDY WOODRUFF: Now, remind us, Miles, why was the moon — it was on the agenda at NASA for a while, but it came off. What was that all about?

　　MILES O'BRIEN: Politics.

　　Of course, we lost the shuttle Columbia in '03. President Bush at the time canceled the shuttle program and said, let's go back to the moon, a program called Constellation. That got some traction.

　　And then, of course, President Obama came in and said, we're not going to the moon. We're going to Mars.

　　And he wouldn't let anybody talk about going to the moon. There were a lot of people who said, you know, we should try the moon first before we move onto Mars, but that got shelved during the Obama administration.

　　Politics now is different, obviously, with the Trump administration there. And I'm told the Trump administration would really like to have U.S. astronauts taking off from a U.S. spaceport some time in its first term. And so this idea of turning that unmanned Space Launch System flight into a crewed mission is gaining a lot of traction.

　　JUDY WOODRUFF: And, finally, Miles, there is this question of money. It costs money to go into space.

　　This is a president who has talked about cutting back domestic discretionary spending. Where's the money going to come from?

　　MILES O'BRIEN: You know, it's interesting.

　　You have to look at the entire space enterprise here. NASA's budget is a little more than $19 billion, but if you look at the budget for the military side of space, it's about $40 billion. So, what if they reconsider this idea of a space council, which they're doing, headed by the vice president, and they start looking at ways to carve out and eliminate some of the redundancies between the military and the civilian side?

　　There may be some ways, even with NASA cuts, that they can borrow from each other, feed each other technology, as it were, military and civilian, which could be a bit of a force multiplier and could make it still possible.

　　JUDY WOODRUFF: Interesting, because the president has talked about spending a lot more money on defense.

　　MILES O'BRIEN: Exactly. So, that money might ultimately help NASA.

　　JUDY WOODRUFF: Miles O'Brien, taking us to the moon and back, thank you.

　　MILES O'BRIEN: To the moon, Alice.

　　JUDY WOODRUFF: Thank you.

　　MILES O'BRIEN: You're welcome.