Today, while glancing over the book Space Chronicles
by Neil deGrasse Tyson, I noticed on page 50 a table listing estimated near-Earth object (NEO) impact risks. Some in the space community argue that asteroid deflection technologies need to be a priority. What then, is the risk of a significant impact?
100 meter-diameter asteroid = 50 megatons of energy, every 1,000 years
200 meter-diameter asteroid = 1,000 megaton, every 10,000 years
The Earth has already survived the Soviet Union’s 50 megaton Tsar Bomba nuclear blast in 1961 without blinking, and the odds are that a NEO will come down over an ocean, so let us assume that we need at least 1,000 megatons to generate serious damage. Although it could happen tomorrow, odds are that by the time something really serious is headed our way (in 5,000 years?) whatever we come up with now will be not just be obsolete. It will be an antiquity.
It might not be a bad idea to build better multi-use telescopes to provide advanced warning of bad surprises, but at the moment there is no obvious imperative need for an operational NEO deflection system.