Besides presenting a physical challenge—one that requires overcoming the hostile terrain of space—the Gravity Well also represents an ascent of achievement. Toward the bottom lies our airline industry, generating $170 billion a year in revenue. Farther up, in low Earth orbit, or LEO, are more than a thousand satellites, monitoring crops and the weather. Still farther, in middle Earth orbit or MEO, several dozen satellites provide our GPS. At the next level, in geosynchronous orbit or GEO, more than 250 satellites enable our Internet, television, and telephone communications.
While governments were first to explore this terrain, it now supports a frontier economy, with basic, low-cost transportation increasingly provided by privately owned companies. This economy is rapidly rising to higher revenues, as entrepreneurs develop more powerful reus- able rockets and smaller, more sophisticated satellites to serve a variety of clients and customers on the ground. Still farther up the Well lie the Lagrangian points, with a few more satellites. Farther up lies the Moon, where we Americans left footprints and then chose to pull back.
All of these points—LEO, MEO, GEO, Lagrangian points, the Moon—occupy the bottom portion of the Gravity Well. At each stage, probes and astronauts scout the terrain, and industry eventually follows. As my book shows, our greatest future depends on our escaping the Well. The very effort will reap tremendous, even unimaginable rewards; but only if we choose to make the effort. Future generations will live off a Gravity Well economy that dwarfs the one on Earth, and they will remember our generation as the one that made the first leap. But only if we choose to make it.