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.

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.

Despite an initially dismal forecast, SpaceX got a break in the weather to send Europe's Hera asteroid probe on its way.