SOLAR SYSTEM

What would we do if a massive asteroid was on a collision course with Earth?

What we would do depends on how much time we have before impact. The NASA-funded Catalina Sky Survey in Tucson, Arizona, where I work, discovers a number of new near-Earth asteroids every clear night. Some of these are very small and can only be spotted when they are close to Earth. These pose no threat to Earth even if they hit.

Our task is to find the massive asteroids many years, decades or, better still, centuries before they may impact. The further into the future the impact will occur, the easier the task of avoiding the collision in the first place. With a long lead time there are many options available to us. In this case we only need a slight change in the velocity to avoid the collision