Did NASA change an asteroid's orbit?
A deliberate impact nudged a small asteroid system
In 2022, NASA intentionally crashed the Double Asteroid Redirection Test (DART) spacecraft into the small moonlet of a binary asteroid system to test planetary defense. The collision shortened the moonlet’s orbit around its parent asteroid and—critically—produced a measurable change to the pair’s path around the Sun. This is the first time human activity has altered an object's heliocentric orbit in a detectable way.
Why this matters
- It proved kinetic impact can transfer momentum to an asteroid and produce a lasting orbital change.
- Measurements of the system’s post-impact motion let researchers refine models of how momentum is exchanged in low-gravity collisions, including how slow-moving ejecta affects outcomes.
- The mission provided real-world data to plan any future asteroid-deflection attempt that might protect Earth.
What scientists learned
Ground-based and spacecraft observations after the impact showed the moonlet’s orbital period around its primary shortened—confirming the impact’s effectiveness. Follow-up tracking detected a tiny change in the pair’s orbit about the Sun, demonstrating that even small adjustments at the level of micrometers per second can be measured with modern astrometry. Images also revealed that the target asteroid system exchanged slow-moving debris after the collision, offering insight into how material launched during an impact can alter dynamics over time.
Limitations and next steps
It remains unclear how similar impacts would scale for larger or compositionally different asteroids. Engineers and planetary scientists are using the DART results to improve simulation tools, design follow-up tests, and plan decision frameworks for an actual defense scenario. Continued monitoring of the impacted system and laboratory studies of low-speed ejecta behavior will refine how best to protect Earth from future asteroid threats.