NASA’s Asteroid-Smashing DART Mission Changed a Space Rock’s Orbit Around the Sun, Marking a First for Humanity
Studying the 2022 collision’s effects can help scientists protect the Earth from celestial objects that might head toward us
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Four years ago, NASA intentionally crashed a spacecraft into the asteroid Dimorphos in the Double Asteroid Redirection Test, or DART. The mission aimed to test our planetary defense capabilities by changing the space rock’s path around its larger companion, Didymos.
DART successfully struck Dimorphos in September 2022, shortening its 12-hour orbit by about 30 minutes. But that’s not all the collision achieved. The blast also changed the asteroid pair’s trajectory around the sun, according to a study published March 6 in the journal Science Advances, marking a first-time feat for humanity.
“If [an asteroid] is ever on its way to hitting the Earth, we can more confidently now say that we have the ability to push them around and away from the Earth,” says lead author Rahil Makadia, a planetary defense researcher previously at the University of Illinois Urbana-Champaign, to Jackie Flynn Mogensen at Scientific American.
Dimorphos and Didymos are gravitationally bound to one another in what’s called a binary system. When the DART spacecraft struck the 560-foot-wide Dimorphos, the impact sent rocky debris flying into space. Makadia and his colleagues suspected that this would change the binary system’s center of mass, and thus its trajectory around the sun.
So, the researchers investigated the asteroid pair’s orbit by using several types of ground-based observations, including stellar occultations. These occur when a celestial body passes precisely in front of a distant star, blocking its light from an observer’s perspective—in this case, on Earth—allowing scientists to determine its speed, shape and position. These can be forecasted, but astronomers need to be in the right place at the right time to collect data.
“Oftentimes it’s amateur astronomers going out in the middle of nowhere to track Didymos based on predictions,” Makadia tells Lisa Grossman at Science News. “There was an observer who drove two days each way into the Australian outback to get these measurements.”
Quick facts: About DART
DART was NASA’s first planetary defense test mission. The asteroid-slamming spacecraft was about the size of a small car and lifted off in November 2021. It struck Dimorphos ten months later at a speed of about four miles per second.
After collecting 22 of these measurements from October 2022 to March 2025, the team calculated that the binary system’s 770-day orbit around the sun was 11.7 micrometers per second—or about 1.7 inches per hour—shorter following DART. That number is tiny, but “over time, such a small change in an asteroid’s motion can make the difference between a hazardous object hitting or missing our planet,” Makadia says in a statement.
Jay McMahon, an aerospace engineer at the University of Colorado Boulder who previously worked with the DART team but was not involved in this study, tells Scientific American that the finding is “very cool.”
“Like any experiment, you can make a prediction about what will happen, but then you have to take the measurements to prove it,” he adds. “And so, this proves it.”
The data also helped the scientists better estimate some of the asteroids’ properties. They calculated that Dimorphos is less dense than previously thought, further hinting that it formed from material shed by the roughly 2,600-foot-wide Didymos. Meanwhile, the larger asteroid is nearly 200 times more massive than Dimorphos, the team found.
More precise measurements of the space rocks’ masses and densities can help scientists better understand how they formed, says Masatoshi Hirabayashi, an aerospace engineer at the Georgia Institute of Technology who was not involved in the study but worked on DART, to Scientific American.
Scientists will soon learn more about DART’s effects on the two asteroids. The European Space Agency’s Hera spacecraft is set to arrive at Dimorphos later this year, where it will survey the impact of the collision. This can inform future strategies to protect our planet from getting struck by celestial objects, though it’s important to remember that the binary system offers only one data point.
All asteroids are a little different, says study co-author Steve Chesley, an asteroid researcher at NASA’s Jet Propulsion Laboratory, to Katrina Miller at the New York Times. But having that one data point “is a lot better than having none.”
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