Astronomers discuss fortifying our planetary defenses

When people think of asteroids, they tend to imagine rare, civilization-ending impacts like those depicted in films such as “Armageddon.” In reality, the asteroids most likely to affect modern society are much smaller. While kilometer-scale impacts only occur every tens of millions of years, decameter-scale (building-sized) objects hit Earth much more frequently: about every two decades. As astronomers develop new ways to detect and track these smaller asteroids, planetary defense becomes increasingly relevant to protecting the space infrastructure that supports modern life, from GPS navigation to global communications.