The DART experiment
NASA’s Double Asteroid Redirection Test deliberately struck Dimorphos in 2022. Follow-up measurements showed that the impact shortened its orbital period around Didymos by far more than the mission’s minimum success threshold.
Why the momentum was amplified
The spacecraft delivered momentum directly, but ejecta blasted from the asteroid added recoil. That amplification depends on surface and interior properties, which vary between objects.
Years of warning are the real superpower
A tiny velocity change applied years before a predicted encounter can move an asteroid thousands of kilometres away from the future collision point. Late discovery leaves much less room for controlled deflection.
A toolbox, not one weapon
Kinetic impactors suit some objects. Gravity tractors, repeated impacts or other methods may suit smaller adjustments, while very large or short-warning threats could require approaches with much higher energy.
Research record
Nature (2023) — DART momentum transferPeer-reviewed · open sourceNature (2023) — Dimorphos orbital period changePeer-reviewed · open sourceNature (2023) — successful kinetic impactPeer-reviewed · open sourceCould We Deflect an Asteroid on a Collision Course?
Direct answer: Yes. Humanity has experimentally demonstrated asteroid-orbit deflection, but a real defence depends on detecting the threat early enough and characterising it well.
Planetary defence has crossed from theory to demonstrated technique; global readiness still depends on surveys, tracking and contingency planning.