The afternoon panel on Monday is on how big the problem is, and what we can do about it.
[Update, it’s starting]
David Morrison is speaking first. He treats asteroids as enemies, while John Lewis treats them as friends. Going through arguments, and explaining what’s been happening in last few years.
Asteroid hazard is one that we can not only mitigate, but eliminate through space technology. First real awareness of hazard goes back to the Alvarez discovery that the dinosaurs were wiped out, and it was a surprise that an event that had no effect on the orbit, magnetic field, or earth itself could wipe out an ecosystem. Referring to a 1991 statement by the Congress that said we should study it internationally, and that while the risk is very small the consequences are very large, and it is a perfect charge: look at the risk, assess the threat, and figure out what to do about it.
Comes in big chunks, can go thousands of years without killing anyone, and then be catastrophic. Showing terrestrial impact frequence graph on log-log scale of megatons of energy on the X axis and frequency on the Y axis (it’s a linear relationship). Upper left is Hiroshima-size event, which occurs almost annually. Tonguska was much worse, and occurs once every few hundred years. Explosions are produced so high in the atmosphere that they don’t reach the ground, and we didn’t realize how often they occur until they got data from Air Force satellites that could see them happening. Those data were invaluable in quantifying the threat. The Air Force had stopped releasing the data a few months ago, but have started to do so again in the last week, though not to the degree of precision that they have themselves, but it’s good enough.
[Update]
D’oh!
I accidentally erased the John Lewis and part of the Morrion talk, and have no obvious way to get it back. Sorry.