How likely is it that an asteroid or a comet of significant size will impact the earth, and what would be the consequences? It is now widely accepted that the dinosaurs were wiped out by such an event, and recent research suggests that previous estimates of the number of asteroid impacts may have been much too low. I only recently learned that it is often possible to see asteroids striking the moon during the annual meteor showers. A video of such an impact is available on the NASA Website, http://www.spaceweather3.com/swpod2006/14jun06/movie760.gif. The impact of even a relatively small object could wipe out a city, and a large one could end human life on earth. Environmentalist-writer Gregg Easterbrook argues that NASA should be expending far more than 0.1% of its budget studying this threat, and what might be done about it. NASA and Congress seem to think that the involvement of astronauts is necessary for the public to support space science, but I think that interest in the Hubble telescope, the Mars Rovers and the brand-new Phoenix lander shows that not to be the case. Why spend billions on the scientifically barren ISS, whose main purpose seems to be as an adventure destination for wealthy tourists, when a possible danger like this looms? When was the last time you heard about real science from ISS? The next problem for it may be how to bring it down without killing anybody.
