NASA’s Double Asteroid Redirection Test mission has achieved a historic milestone. Scientists say the spacecraft changed the orbit of an asteroid system around the Sun. It is the first time a human made object has measurably altered the path of a celestial body in solar orbit.
The DART spacecraft intentionally crashed into the asteroid moonlet Dimorphos in September 2022. The mission aimed to test a planetary defense technique called a kinetic impact. This method attempts to deflect dangerous asteroids by striking them with a spacecraft.
Dimorphos is about 560 feet wide. It orbits a larger asteroid called Didymos. After the collision scientists confirmed that the impact shortened Dimorphos’ orbit around Didymos by about 33 minutes.
New research now shows the effect went even further. The collision also changed the entire binary asteroid system’s motion around the Sun. Didymos and Dimorphos normally orbit the Sun every 770 days.
Researchers found the system’s orbital speed changed by about 11.7 microns per second. That equals roughly 1.7 inches per hour. The change is extremely small but still measurable.
Scientists say even a small shift like this can matter over long periods of time. A tiny change in speed can slowly alter an asteroid’s future path. Over years or decades that difference could determine whether an asteroid misses Earth or collides with it.
The impact produced a large cloud of debris. Some of that material escaped the gravity of the asteroid pair. As the debris flew away it carried momentum with it. This effect increased the force of the impact and helped push the asteroid slightly off its original path.
The mission was designed as a test rather than an emergency defense. Dimorphos and Didymos were never considered a threat to Earth. Scientists chose the target because it allowed them to safely study the impact results.
Researchers confirmed the change using a method called stellar occultation. Astronomers observed the asteroids passing in front of distant stars. The brief dimming of starlight helped scientists measure tiny changes in the asteroids’ position.
The results support the idea that kinetic impact could protect Earth from dangerous asteroids. NASA is now preparing additional planetary defense tools. One upcoming project is the Near Earth Object Surveyor mission. The telescope will search for asteroids that could pose future risks to Earth.
The European Space Agency’s Hera spacecraft will also visit the Didymos system. The mission is expected to arrive later and provide detailed observations of the impact site.
