What EP actually knows about the cometary impact issue is oprobably best expressed by impact expert Duncan Steele at Grondime's beloved CCNet on 4/24/01 at #(9) GRONDINE'S MISREPRESENTATIONS

What real impact experts have to say is that NEA's represent most of the hazard as Grondine did until recently. He used to justify a lunar observatory to detect small impactors based on frequency rates far higher than calculated by experts who based their estimates on lunar cratering and current NEA observations. He used to deny comets constituted a major hazard when it was pointed out that Mars Colonization was the best option to protect humanity from extinction in the event of such an impact.

Now that a proposal for a lunar option has been put forward based on small impactors and a comet detection lead time increase that is basically useless against an ELE Grondine has changed his tune. Real impact experts (who of course did not invite Grondine) convened recently to discuss the next phase of NEO searches and concluded in Report of the Near-Earth Object Science Definition Team that comets were not the next priority. They base this on refinements of earlier estimates putting comets at only 1% of the potential impacts. The reasons why are old news that were basically reported long ago in the Spaceguard Survey in Chapter 2: Hazard of Cosmic Impacts. Clicking on the titles take you to the report for all those that seem to have trouble finding information from people who actually know what they are talking about with respect to impacts. Graphs there indicate many options costing far less than a lunar base capable of drastically cutting the risk of impact remaining after the current program is completed.

Comets do represent most of the risk at the high end of the size scale but we can not currently divert them as Steele notes and an ELE event is extremely rare. To be able to actually deflect them we need the type of technology likely to develope in a spacefaring civilization. We need far more robust space technology than we currently have to stop ELE events, and we most likely have more than enough time to develope it if we don't give up on the opportunity to do so.

To Mary-Anne and others complaining about wasting time responding to Grondine. Do you see that there are a few Grondine still manages to flamboozle including those that supposedly are well educated?

Regards,
Mark