On September 26, 2022, humanity graduated from passive cosmic spectators to active defenders of Earth. Seven million miles away, NASA’s Double Asteroid Redirection Test (DART) slammed into the asteroid moonlet Dimorphos at 14,000 miles per hour. Driven in its final hours by SMART Nav—an autonomous optical navigation algorithm tracking an unknown target no larger than a football stadium—the refrigerator-sized probe struck dead-center. The kinetic impact permanently altered Dimorphos’s orbit around Didymos by 33 minutes, shattering expectations and leaving a thousands-of-miles-long debris trail. For 4.5 billion years, orbital mechanics have dictated terrestrial extinction events without appeal. With DART’s deliberate, software-guided collision, humanity cast its first vote against the dinosaurs' fate, proving that planetary defense is no longer speculative science fiction, but demonstrable engineering.