1. Have you thoroughly read chapter 5?

2. Which American is credited with important advances in rocketry?

3. What is the most common element in the Earth's atmosphere?

4. How does the surface area of Mars compare with the land area of Earth?

5. What is terraforming?

6. What kind of dark self-replicating "machine" does Sagan propose putting on Mars' ice caps to melt them and release the ancient Mars atmosphere?

7. Which spacecraft landed on Mars in 1976?

8. Which planet's atmosphere is more dense, Mars' or Earth's?

9. What was Lowell's idea of the Martians?

10. Who was Wolf Vishniac?