NASA's Double Asteroid Redirection Test (DART) mission has been confirmed as a landmark success in planetary defense. On September 26, 2022, the DART spacecraft intentionally collided with Dimorphos, a small moonlet orbiting the larger asteroid Didymos. The goal was to test whether a kinetic impact could alter the trajectory of a celestial object, a technique that could one day be used to protect Earth from a potential asteroid impact.
Detailed analysis published in 2023 confirmed the impact was highly effective. Before the collision, Dimorphos took approximately 11 hours and 55 minutes to orbit Didymos. Post-impact observations showed its orbital period was shortened by 33 minutes, a change far greater than the minimum benchmark of 73 seconds NASA had set for mission success. This significant alteration demonstrates that a kinetic impactor can indeed change an asteroid's motion.
The mission was a collaboration between NASA and the Johns Hopkins Applied Physics Laboratory (APL). The European Space Agency's (ESA) Hera mission is scheduled to launch in October 2024 to conduct a detailed post-impact survey of the Didymos system, providing further data on the crater left by DART and the asteroid's changed properties.
This successful test provides crucial data and validation for a viable planetary defense strategy. While no known asteroid poses a significant threat to Earth for at least the next century, the DART mission proves humanity has a viable technological approach to deflect a hazardous asteroid if one were ever discovered on a collision course.
