Asteroid deflection could save Earth, or accidentally doom it, depending on where we aim the impact.

Scientists caution that asteroid deflection must be precise, as striking the wrong spot risks sending it through a gravitational keyhole that sets up a future collision with Earth. Using lessons from NASA’s DART mission, researchers are developing probability maps to guide safer impact strategies.

Selecting the right spot to smash a spacecraft into the surface of a hazardous asteroid to deflect it must be done with great care, according to new research presented at the EPSC-DPS2025 Joint Meeting this week in Helsinki. Slamming into its surface indiscriminately runs the risk of knocking the asteroid through a ‘gravitational keyhole’ that sends it back around to hit Earth at a later date.