Climate change, global pandemics, bioterrorism, nuclear warfare, artificial intelligence run amok—today’s world offers no shortage of homegrown existential risks to worry about. But one of the most worrisome hazards doesn’t come from Earth at all. Rather, it’s from the astronomical numbers of asteroids and comets that come close to our planet as they orbit the sun. Most of these objects pass by harmlessly, and the vast majority are too small to cause a global crisis even if a cosmic collision occurs, but every now and then a big one hits, to cataclysmic effect. For proof, look no further than Chicxulub, the “Crater of Doom” carved into the Yucatan Peninsula seafloor 66 million years ago by a 10-kilometer-wide asteroid that led to the mass extinction of more than half of Earth’s species, including the dinosaurs. It happened before, and sooner or later it’s likely to happen again—unless, that is, we see the next doomsday impactor coming and manage to somehow prevent its apocalyptic planetfall.
The threat may seem like pure science fiction, but under the umbrella term of “planetary defense,” scientists and engineers around the world treat it with absolute seriousness. In his latest book, How to Kill an Asteroid: The Real Science of Planetary Defense, acclaimed science journalist Robin George Andrews offers a sometimes scary, often humorous and always erudite account of the people and projects striving to safeguard Earth from space rocks and help humanity avoid the dinosaurs’ dismal fate.
Scientific American spoke with Andrews about the state-of-the-art in asteroid detection and deflection techniques, the worst-case scenarios and the reasons for optimism about averting disaster.
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