NASA’s DART (Double Asteroid Redirection Test) spacecraft changed the motion of an asteroid system in space, demonstrating that a kinetic impactor could be a viable way to deflect a near-Earth object if one ever threatened Earth.

New findings show that when the spacecraft deliberately crashed into the asteroid moonlet Dimorphos in September 2022, the impact did more than alter the small body’s motion around its larger companion, Didymos. The collision also slightly changed the path that both asteroids follow around the Sun. Didymos and Dimorphos are gravitationally bound and circle a shared center of mass, forming what astronomers call a binary asteroid system. Because the two bodies are linked in this way, changing one affects the other.

First Measurable Human Impact on a Solar Orbit
According to a study published in the journal Science Advances, scientists carefully tracked the motion of the asteroid pair after the collision. They discovered that the system’s 770-day orbit around the Sun shifted by a fraction of a second following the DART impact.

This marks the first time that a spacecraft built by humans has measurably changed the solar orbit of a natural object.

“This is a tiny change to the orbit, but given enough time, even a tiny change can grow to a significant deflection,” said Thomas Statler, lead scientist for solar system small bodies at NASA Headquarters in Washington. “The team’s amazingly precise measurement again validates kinetic impact as a technique for defending Earth against asteroid hazards and shows how a binary asteroid might be deflected by impacting just one member of the pair.”