I don't want to hijack this, but just an observation along these lines.
We could have one of those extinction-level cosmic events any day now (or not for hundreds of thousands of years). The cost to identify a potential asteroid of doom is not that great by GNP standards. Science has reached the point where we might be able to do something about it if caught early enough.
To some extent we are all on the second floor, watching the water rise and thinking about moving to the attic instead of being behind appropriately reengineered levees.
Charon