Johnson explains interstellar travel.

Transcript: "Interstellar is a mission beyond our solar system, 'inter' being 'between, between the stars.' That's a region of space that we have yet to explore, and we're now developing the technologies that are going to enable us to take those first steps that'll eventually, someday in the future, maybe let us consider taking a voyage to another star."

Sails move extremely fast.

Transcript: "A solar sail enables you to travel a lot faster than a conventional rocket. The missions that we're talking about will travel between 50-60 miles per second. To put that into perspective, that would be the equivalent of going from New York to Los Angeles in under a minute."

Johnson compares sailing in space and on Earth.

Transcript: "Sailing with a solar sail is very similar to what you would do with a sailboat on Earth. On Earth you use the wind to push your sail, and you can tack against the wind to move the sailboat in the direction you want to go. The very same situation exists in space, only instead of the wind, you use sunlight."

Space sails move from sci-fi to "sci-fact."

Transcript: "There are a lot of things that were science fiction just a few years ago that we've done. The best example would be that the Apollo missions in the 60's were the science fiction of the 30's. The stuff that we're talking about now, the science missions and the missions to go beyond the solar system, are the kinds of things I was reading as a kid. We're on the verge of making that a reality today."