NASA's DART impact altered asteroid Dimorphos orbit
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NASA's DART spacecraft deliberately crashed into the asteroid Dimorphos on September 26, 2022, altering its orbit around the larger asteroid Didymos. The impact shortened Dimorphos' orbital period from 11 hours 55 minutes, marking the first time humans changed the motion of a celestial object. The test demonstrated a kinetic impact technique for planetary defense, though no asteroid threatened Earth.
The Mission Design
NASA chose the Didymos-Dimorphos binary system because neither body threatened Earth, allowing a safe measurement of the impact. The 570-kilogram DART spacecraft guided itself autonomously during the final 90,000 kilometers, crashing into Dimorphos at about 22,530 kilometers per hour. The impact was confirmed at 7:14 p.m. EDT on September 26, 2022, from mission control at the Johns Hopkins Applied Physics Laboratory.
The Principle and Result
The kinetic impact technique transfers momentum from a fast-moving spacecraft to an asteroid, altering its trajectory. DART's hypervelocity impact changed Dimorphos' orbit around Didymos, making it the first time humans deliberately changed the motion of a celestial object. The asteroid's orbital period was reduced from 11 hours 55 minutes, as measured by astronomers observing brightness dips from Earth.
The Aftermath Observation
A small Italian Space Agency CubeSat, LICIACube, separated from DART days before impact and flew past the asteroid system to photograph the collision's aftermath. The spacecraft's camera, DRACO, returned increasingly detailed images until transmission stopped at impact. DART was built to be destroyed, with its success condition being contact, not survival.
What's Next
NASA and international partners will analyze data from DART and LICIACube to refine planetary defense models. It remains unclear whether a kinetic impactor could successfully deflect a larger asteroid or one with a different composition.
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NASA's DART impact altered asteroid Dimorphos orbit
