http://www.boulder.swri.edu/clark/ncar.html 6 years old since the last time the author has revised, but nothings really changed that much. they are still out there, they can still impact the earth. and we still have only partial coverage of the skies to see them coming in. http://impact.arc.nasa.gov/ more docs to read for info at the end of the day, small projects that benefit mankind in one way or another, SETI research for future contacting of other races, even changing the very technology we use in our lives can all be wiped out in an instant by something we have virtually no chance of detecting and no method of avoiding yet. should we put effort into arming the ISS with something capable of dealing with asteroids? Can a mass driver on the moon be capable of playing "snooker" with something incoming, because i know the SG1 team (fictional!) can't fly up and extend a force field round a real asteroid so it passes harmless through the earth!