Instead of astronauts, exploration has been left to robots, which attract passionate fans of their own. As Shindell observes, a trip to Mars “always seems to be two or three decades in the future,” allowing policies in the present to be justified or forgiven indefinitely. To his credit, Shindell persuasively argues that Mars is most instructive when it sheds light on how we see ourselves. Proposals for Martian colonies are often tangled up with the language of capitalism and privilege, treating the planet as an escape hatch that minimizes the need to solve problems on Earth. It fills the same imaginative role today that America once did for Europe, which underlines the danger of exporting old assumptions to an undiscovered country.

---