In September 2022, humanity crossed a threshold it had long theorized but never tested: the deliberate movement of a celestial body. NASA's DART spacecraft, no larger than a household appliance, struck the asteroid Dimorphos at nearly 23,000 kilometers per hour and shortened its orbit by over 33 minutes — far exceeding expectations. The mission did not merely validate an engineering concept; it transformed planetary defense from a philosophical contingency into a demonstrated capability, offering the species its first rehearsed answer to one of nature's oldest and most indifferent threats.