The Impact Hazard

The existence of craters on Earth shows that impacts have happened in the past. Less than a hundred years ago an asteroid or comet was most likely the cause of a huge explosion at Tunguska  (Siberia). In our own time the impact of comet Shoemaker-Levy into Jupiter left no doubt that such impacts can still happen in the solar system and gave us some idea of just how much energy is released when they do.  And, we know that there are currently objects with the long-term potential to impact Earth.  These are the many "potentially hazardous asteroids" that have Earth-crossing orbits. The amount of energy released in an asteroid impact would be staggering. The impact of a one-kilometer asteroid could easily release as much energy as millions of Hiroshima bombs.

None of the currently known asteroids will hit Earth during the next century. However, almost certainly there are many, many asteroids that have yet to be discovered.  And so, it makes a lot of sense to search, search, search, and search for asteroids and to develop an understanding of their orbits.

But, what if someday we do find an asteroid that is on a collision course with Earth? What will we do?  Whatever approach we take to mitigating the hazard, one thing is for sure - we'll need to know a lot about the physical properties of the object we're trying to deflect or destroy.  So, in addition to discovering asteroids, it also makes sense to study them with a variety of techniques including radar and to determine their physical characteristics.  Understanding these small worlds is the goal of the research that is described on these pages.

If you want to pursue the impact hazard subject more, the Yahoo! Earth-Impact page contains quite a few interesting links, of which the Asteroid and Comet Impact Hazards page is one of the most interesting