Lauber sets the stage by using the analogy of a crew's limited supplies on board a space shuttle ("They cannot get more of anything.") to get across the idea of earth's limited supply of air, food and water. She then goes on to describe earth's natural cycles and the impact human beings have had on them, especially in the past 100 years. (Ages 4-8)

The earth is like a spaceship in orbit—it has everything on board that we need to survive: water, food, and air with oxygen. Unlike a space shuttle, Earth is able to renew its resources. Read and find out why Earth is the greatest spaceship to be aboard!