In a historic first for humanity, NASA’s DART mission has proven it can move a celestial body through space. When the spacecraft deliberately slammed into the asteroid moonlet Dimorphos in September 2022, it did more than just alter its orbit around its partner, Didymos. New research published in Science Advances reveals the impact also slightly shifted the path of the entire binary system around the Sun.
While the change is minuscule—altering the system’s 770-day solar orbit by a mere 0.15 seconds—it marks the first time human technology has measurably changed a natural object’s trajectory around the Sun.
The key to this planetary defense milestone lies in the massive debris cloud kicked up by the impact. The force of the ejected material acted like an extra thrust, doubling the momentum imparted to the asteroid. This explosive recoil not only shortened Dimorphos’ orbit around Didymos by 33 minutes but also gave the combined system a slight nudge, changing its solar orbit speed by just 1.7 inches per hour.
To verify this minute change, scientists relied on a global network of volunteer astronomers. They tracked “stellar occultations”—moments when the asteroid passed in front of distant stars—to measure Didymos’ position with extreme precision. These observations confirmed that the binary system had indeed been pushed. The study also revealed that Dimorphos is a “rubble pile” less dense than previously thought, supporting the theory it formed from material shed by its larger companion.
“This is a tiny change,” said NASA scientist Thomas Statler, “but given enough time, even a tiny change can grow to a significant deflection.” The findings validate the kinetic impact technique and pave the way for future planetary defense missions like NASA’s NEO Surveyor, which will hunt for hazardous asteroids long before they pose a threat to Earth.
