Realistically, there is no reason to assume that the next dinosaur killer-class impactor is even in the current NEO population: such impacts are so widely spaced & NEO orbits are so instable that the next Chicxilub is probably drifting happily in the Edgeworth-Kuiper Belt even as we speak, gloriously beyond the ability of our orbital modelling to determine as a threat.

Smaller objects (Tunguska class) are more immediate threats; but statistical analysis quoted by you personally show that such imapacts are separated by (roughly) a century on more; on a planet where almost 90% of the surface (the bulk of our oceans, where original estimates of massive tsunami activity from such an imapct/airburst have been massively reduced; plus great slabs of deserted continental mass) would be able to take such an impact with minimal loss of human life & property... always assuming that we didn't detect the threat decades in advance (which - given the likelihood that an actual impact will be set up by one or more resonant flybies - is very likelihood), giving us time to either evacuate the targetted area or combat the actual threat of the object.

The idea that a long duration comet of any significant size would actually hit us directly is so implausible as to be almost laughable: realistic cometary impacts will almost certainly follow a period of orbital correction similar to that undergone by our hypothetical EKO Chicxilub... multiple Jupiter close encounters to trap its orbit in the inner solar system; followed by a number of other planetary - including terrestrial - flyby encounters. Plenty of time for warnings without massive Lunar infrastructure.

What that tells anyone who looks at the numbers objectively is that we are talking (at best) at millenial events for real damage; whereas you're mickey mousing about the threat as though the NEO impactor issue was a realistic short term threat requiring Apollo class expenditure. Your assessment is scientifically fascinating but frankly exploitative of the impactor threat (in exactly the same way that Teller & his big bomb friends tried to exploit the threat post SL9); & does you - & the issue - no credit at all.

Robert