Two years ago, a NASA spacecraft smashed into a small asteroid millions of miles from Earth to test a technique that could one day prove useful to deflect an object off a collision course with Earth.

Scientists are eager to examine the impact’s aftermath up close to know exactly how effective Dart was and what changes might be needed to safeguard Earth in the future.

A NASA spacecraft knocked into an asteroid two years ago to test planetary defense. Now, a new mission will inspect the damage, with the goal of helping future asteroid deflection.