Hi David -

All true, and "amateurs" are also responsible for a very large number of comet discoveries. Of course, given the skill level and equipment of some of the amateurs, are they really "amateur"?

If the problem were as Morrison et al. maintain, all simply asteroids in relatively stable orbits that make multiple passes before hitting, then ER's proposal might make some sense. But reality is different.

Statistically, on the low end what is likely to hit is a 75 m dead comet fragment, and it is likely that no amateur telescope is going to find them before they hit. Too damned dark. What is needed is 45 minutes warning.

On the top end, for LPC telescopes on the Moon would provide 6 months more warning than large Earth based telescopes. That's a second shot.

If you have not seen NASA Langley's CAPS analysis, you should take a look at it.

Its been a long fight to get money to deal with this professionally, and just about every means fair and foul has been used by other "clients" to ensure that taxpayers' money is not diverted from "their" pockets. This includes in particular both manned Mars enthusiasts and cosmologists.

What should the "amateur" role be once the professional systems are iin place? I don't know. What should the role of smaller observatories educational and say east european observatories be then? I don't know. How do we develop tomorrow's professional NEO astronomers? I don't know. Some are more interested in preserving "their" cash than examining these problems.

Let's move on to a current cases. We have 64 fragments of SW3 in a 6 million kilometer long chain heading back by Earth shortly. Clean passes are expected in 2011 and 2017, but the whole chain will be perturbed. There most likely will be VERY near encounters in 2022, say around 5 kt, based on historical record. Of course, the encounters could be larger - I don't know. Will the fragments outgas? I don't know.

Where will 2004 MN4 be after its pass by in 2029? I don't know.

Though there are wonderfully gifted amateurs out there, I am not comfortable relying on amateur efforts to track these.

But then all of this is not my job, nor my responsibilty. It's Mike Griffin's, by act of Congress.