Four decades after Apollo 11 landed on the moon, we seek clean energy sources, a healthy environment, and a peaceful world. To achieve these goals we must implement new approaches. "Business as usual" is no longer acceptable. Energy and resources are limited on the Earth and acquiring them adversely impacts the environment. In space, however, they are present in abundance and can be acquired without damaging ecosystems. Crossing the Threshold: Advancing into Space to Benefit the Earth shows how we can achieve a secure, sustainable future—with abundant energy, resources, and opportunities for all to have more fulfilling lives.