It's next because we emerged from the cave and found two sticks and made fire. Because we crossed valleys and mountains and explored. Because we built ships and discovered new countries and new peoples and charted the world. Because we looked to the heavens and decided: It's next.
Space is next -- probed but unconquered, examined but unpainted. For 40 years a select, lucky few have lived it, felt the yank of g-forces as they shot past the yokes of gravity and burst into the blackness and wonder and possibility that exists in space.
In the next 40 years, it could be anyone. Society is hurtling toward the day when the average person could walk into a spaceport and buy a ticket for the moon, for a space hotel, for a quick trip across the planet.