NASA's Double Asteroid Redirection Test spacecraft deliberately impacted the asteroid moonlet Dimorphos, measurably changing its orbit around the Sun [1].
This achievement marks the first time a human-made object has altered the trajectory of a celestial body. The result provides critical data for planetary defense, demonstrating that humanity can potentially redirect a hazardous asteroid before it reaches Earth.
The impact occurred on Sept. 26, 2022 [1]. The target was the binary asteroid system Didymos–Dimorphos, where Dimorphos is a moonlet roughly the size of the Great Pyramid [2]. By striking the smaller body, the DART spacecraft shifted Dimorphos' orbit around its parent asteroid, Didymos, as well as its broader path around the Sun [1, 2].
NASA designed the mission to test whether a kinetic impactor could shift the trajectory of a potentially hazardous asteroid [3, 2]. The mission focused on the physics of the collision and the subsequent movement of the asteroid. Because the target was a binary system, researchers could measure the change in the moonlet's orbital period more precisely than they could with a single asteroid.
The success of the Sept. 26, 2022 [1] mission serves as a proof of concept for the kinetic impactor technique. Scientists can now use this data to refine models of asteroid composition, and how different materials respond to high-speed collisions. This knowledge is essential for future missions intended to protect the planet from cosmic impacts [3].
“The first time a human-made object has altered the trajectory of a celestial body.”
The DART mission transitions planetary defense from theoretical modeling to a demonstrated capability. By proving that a kinetic impact can measurably alter an asteroid's orbit, the mission establishes a viable mechanism for mitigating the risk of future asteroid collisions with Earth, provided such threats are detected early enough to launch an interceptor.
