NASA is developing satellites that'll help deflect asteroids away from Earth, potentially avoiding significant disruptions to life on the planet. A project known as Double Asteroid Redirection Test (DART) has made the move from "concept development" to "preliminary design."
DART involves using a spacecraft to hit an asteroid to send it on a different path.
The spacecraft is only the size of a fridge, so it doesn't have a ton of power. However, as long as you deal with the asteroid early enough, just a tiny course change will prevent an impact.
DART is a critical step in demonstrating we can protect our planet from a future asteroid impact, - Andy Cheng, co-leader, DART project
A test of DART will occur in 2024, when the spacecraft will be used to alter the course of an already non-threatening asteroid called 65803 Didymos.