DART

Key facts

Mission & specifications

Mission

DART — the Double Asteroid Redirection Test — was humanity's first experiment in planetary defence: a deliberate attempt to change the orbit of an asteroid by crashing into it. No known asteroid threatens Earth in the foreseeable future, but DART was a rehearsal, to find out whether a 'kinetic impactor' could actually nudge one aside if we ever needed to. Launched on 24 November 2021, the refrigerator-sized spacecraft steered itself, in the final hours, toward a target it could not even see until shortly before impact: Dimorphos, a 160-metre moonlet orbiting the larger asteroid Didymos. On 26 September 2022 DART slammed into Dimorphos at about 22,000 kilometres per hour, destroying itself in the process while a small Italian cubesat, riding along behind, photographed the spray of debris. The test was a clear success. By watching how the moonlet's orbit around Didymos changed, astronomers found that the impact had shortened it by about 32 minutes — far more than the minimum needed to count as a deflection, and more than expected, because the plume of ejected rock gave an extra push. DART proved, for the first time, that we could move an asteroid.

1. 2021Launch toward DidymosLaunch

   A small impactor sets out on humanity's first planetary-defence test.

2. 2022Impact on DimorphosImpactor

   Steers itself into the 160-metre moonlet at ~22,000 km/h, destroying itself on contact.

3. 2022The plume photographedMilestone

   A trailing Italian cubesat, LICIACube, captures the spray of ejected debris.

4. 2022Deflection confirmedMilestone

   Measurements show the impact shortened Dimorphos's orbit by ~32 minutes — far beyond the success threshold.

Images

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