NASA's DART Alters Asteroid Orbit Around Sun

NASA's Double Asteroid Redirection Test mission achieved a historic milestone in planetary defense by altering the orbit of a binary asteroid system around the Sun for the first time through human intervention, according to a new analysis of observations collected since the 2022 impact.

On September 26, 2022, the DART spacecraft, traveling at approximately 15,000 miles per hour, intentionally collided with Dimorphos, a 160-meter-wide moonlet orbiting the larger asteroid Didymos. The pair, located millions of miles from Earth, posed no threat to the planet but served as an ideal test target for the kinetic impactor technique. Initial assessments confirmed the collision shortened Dimorphos's orbit around Didymos by 32 minutes, demonstrating the method's potential to deflect hazardous asteroids.

Recent measurements, however, reveal a subtler but significant effect on the system's broader path. Researchers analyzed nearly 6,000 ground-based radar observations and 22 stellar occultation events—moments when the asteroids passed in front of distant stars, briefly dimming their light. These precise timings, gathered by a global network of professional and amateur astronomers from...