Slide 1
Test a small change in motion
The Double Asteroid Redirection Test deliberately struck Dimorphos on 26 September 2022. It tested whether a spacecraft impact could measurably change an asteroid’s motion.
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Dimorphos is the moonlet of the larger asteroid Didymos. The pair did not pose a threat to Earth, making the encounter a planned experiment rather than an emergency interception.
Slide 2
An impact transfers momentum
The spacecraft delivered momentum when it hit. Material thrown from the asteroid also carried momentum, creating an additional recoil on the remaining body.
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The result therefore depends on how the surface responds, not just on spacecraft mass and speed. A porous or loosely bound target can behave differently from a solid monolith.
Slide 3
The companion provided a measurable clock
Astronomers tracked Dimorphos’s orbit around Didymos before and after the impact. Its orbital period shortened by about thirty-three minutes.
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A change in the mutual orbit could be measured from Earth using repeated observations. This made a binary asteroid a useful experimental target even though the direct velocity change was small.
Slide 4
The effect extended to the pair’s solar orbit
Research reported in 2026 also measured a change in the asteroid pair’s motion around the Sun. The impact affected more than the moonlet’s relative orbit.
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Interpreting the result requires accounting for escaping debris as well as the two bodies. The experiment provides evidence for physical models rather than a universal conversion from impact speed to deflection.
Slide 5
Deflection planning needs lead time and knowledge
A small velocity change can accumulate into a useful positional difference over time. Applying the method to a real threat would require early detection and a suitable mission.
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Target mass, structure and orbit influence the needed intervention. Follow-up measurements, including the goals of Europe’s Hera mission, help determine how far this experiment can guide another case.
Sources
- NASA’s DART Mission Changed Orbit of Asteroid Didymos Around Sun
NASA
- Characterization of the DART Impact Site on Dimorphos
NASA Technical Reports Server
- Hera’s Science
European Space Agency