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