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Answer: NASA's Double Asteroid Redirection Test (DART) was the first-ever mission dedicated to demonstrating asteroid deflection by kinetic impact. On Sept. 26, 2022, DART deliberately hit Dimorphos, a moonlet about 530 feet (160 meters) in diameter orbiting the larger, 2,560-foot (780-meter) asteroid Didymos, and changed its orbit.

The result

NASA announced on Oct. 11, 2022, that data from DART's investigation team showed the impact successfully altered the smaller asteroid's orbit. This marked the first time humanity had purposely changed the motion of a celestial object, and the first full-scale demonstration of asteroid deflection technology. In March 2026, research indicated the impact also shifted the orbit of both asteroids around the Sun.

Why this target

Didymos and Dimorphos make up a binary asteroid system, meaning they orbit each other around a shared center of mass. They are not a threat to Earth, but because they pass relatively close to our planet they were chosen as DART's target. DART was NASA's first mission to test planetary defense technology, which could one day be used to deflect hazardous asteroids on a collision course with Earth.

Mission facts

• DART launched at 10:21 p.m. PST, Nov. 23, 2021, aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California.
• Didymos, which means "twin" in Greek, was discovered on April 11, 1996, by Joseph Montani of Spacewatch at Kitt Peak National Observatory.

Claims

• id: C1 claim: DART impacted the moonlet Dimorphos on Sept. 26, 2022. source: S1 evidence: "On Sept. 26, 2022, DART impacted the asteroid moonlet Dimorphos"
• id: C2 claim: Dimorphos orbits a larger asteroid called Didymos. source: S1 evidence: "It orbits a larger, 2,560-foot (780-meter) asteroid called Didymos."
• id: C3 claim: DART deliberately impacted Dimorphos on Sept. 26, 2022. source: S2 evidence: "DART deliberately impacted Dimorphos on Sept. 26, 2022."

Sources

• [S1] Double Asteroid Redirection Test (DART). NASA. https://science.nasa.gov/mission/dart/ . License: US government work, public domain. Accessed 2026-11-04.
• [S2] Didymos & Dimorphos. NASA. https://science.nasa.gov/solar-system/asteroids/didymos/ . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_fcxvak1d,
  author = {{iinventedlight}},
  title = {{DART: the first test of asteroid deflection}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/dart-mission/},
  note = {Permanent ID iil:note:fcxvak1d. License: CC-BY-4.0.},
}

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