At the beginning of the twenty-first century, people are excited by the prospect of visiting new worlds in outer space. While international space agencies continue robotic exploration of planets and asteroids in the solar system, other government agencies are planning a return to the Moon and expeditions to Mars. What is the logic of establishing a settlement on the Moon as a precondition for human settlement of Mars and beyond? Answers to this question include satisfying the need to explore, increasing scientific knowledge, enhancing understanding of life in the universe, discovering whether life existed on Mars, igniting the human spirit, making use of resources on the Moon and Mars, and ensuring the survival of humankind. Once humans have mastered the lunar environment, they will have the technical knowledge to reach Mars, Jupiter, and the stars.

A proposed inflatable habitat is illustrated here. This habitat could be used as...