NASA’s DART (Double Asteroid Redirection Test) spacecraft made history in September 2022 by colliding with the asteroid moonlet Dimorphos. This wasn’t just a simple impact; it changed both Dimorphos’s orbit around its bigger sibling, Didymos, and even shifted their shared path around the Sun.
A recent study published in Science Advances confirmed that after the DART impact, the 770-day orbital cycle of Didymos and Dimorphos around the Sun altered by a mere fraction of a second. This marks the first time a human-made object has changed a celestial body’s path in the solar system.
Thomas Statler, who heads solar system small bodies at NASA, noted, “Even a tiny change can grow significant over time. This shows that kinetic impact could be a technique for defending Earth from asteroids.”
The DART collision ejected a massive cloud of rocky debris from Dimorphos, which altered its shape (the asteroid is about 560 feet wide). This debris had its own momentum, which amplified the push from DART—scientists refer to this as the momentum enhancement factor. The recent findings indicated this factor was about two, meaning the impact’s effect was doubled by the debris expelled during the crash.
Earlier studies indicated that Dimorphos’s orbit around Didymos shortened by 33 minutes. The latest research reveals that the impact also changed the binary system’s orbital period around the Sun by 0.15 seconds. “This shift in speed was about 11.7 microns per second, equivalent to 1.7 inches per hour,” said Rahil Makadia, the study’s lead author.
While Didymos wasn’t on a collision path with Earth, this highlight illustrates how kinetic impactors can potentially steer hazardous asteroids off course. The key lies in spotting near-Earth objects early enough to act.
To help with this, NASA is developing the Near-Earth Object (NEO) Surveyor, a telescope aimed at locating difficult-to-find asteroids and comets that could pose a risk.
To measure the DART’s effects on both asteroids, researchers meticulously tracked Didymos’s orbit. They used a method called stellar occultation, which involves watching the asteroid pass in front of a star and momentarily blocking its light. This technique requires precise timing and location, making it a challenging observation task. Luckily, dedicated volunteer astronomers recorded 22 of these occultations between October 2022 and March 2025.
Steve Chesley, a senior research scientist at JPL, emphasized the teamwork that made this study possible, noting that these efforts would not have succeeded without the commitment of volunteer observers. The tracking also helped scientists measure the densities of both asteroids, revealing that Dimorphos is slightly less dense than previously believed, supporting the idea it formed from debris shed by Didymos.
The DART mission was a groundbreaking effort, marking humanity’s first attempt to alter a celestial object’s path. It emphasizes the importance of planetary defense and our growing ability to interact with space effectively.
For more details on the DART mission, visit: NASA DART Mission
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Asteroids, Astronomy, DART (Double Asteroid Redirection Test), Didymos & Dimorphos, Planetary Defense, Planetary Defense Coordination Office, Potentially Hazardous Asteroid (PHA)
