Finally, it seems, there is a sincere interest in tracking asteroids. Their devastation would outweigh all other catastrophes. My questions are: Are the trackers involved, trying to keep track of the effects of other large bodies when the asteroids are not near the earth? It seems only a very slight gravitational effect could cause a known orbit to take on a different tragectory: one that might impact our planet. Is there enough attention paid to the ones with a regular, repeating orbit? Are they routinely re-assessed as they approach? It just seems to me that they could be easily altered (not on purpose) while out at their apogee. The mathematics of an orbit shows how small a nudge would be needed to cause a strong, later shift.