[meteorite-list] Earth/Moon impact modeling

From: E.P. Grondine <epgrondine_at_meteoritecentral.com>
Date: Mon, 4 Jul 2011 18:02:17 -0700 (PDT)
Message-ID: <1309827737.68463.YahooMailClassic_at_web36903.mail.mud.yahoo.com>

Hi Chris -

"The folks at NASA who are working on this are extremely competent, and
are in close association with meteoritics research groups at
universities and observatories around the world. To suggest that these
people are incompetent says more about you than it does them."

I did not say that those NASA works with are incompetent. Many of them have
put great effort into trying to straighten NASA researchers out.

"Nobody has a good idea about ELE scale events, because they are so rare
as to make statistics useless."

Actually, we do have really good data for both multi-species ELE and human ELE. Neither agree with the models.

"But we have a very good idea about the local meteoroid environment,"

Actually, asteroid population estimates have risen dramatically in recent years, and the formation hypotheses have undergone several revisions and are under constant improvement. Comet source populations are unknown.

"including good estimates for lunar impacts, which are regularly observed."

Assuming no periodicity or spikes, both of which are huge assumptions.

"Reasonable estimates now exist for material distribution, including size, velocity, and orbits, from dust through tens of meters. These estimates are backed up by observational evidence from space-borne test surfaces, the previously mentioned lunar impact data, hundreds of thousands of optically recorded meteors, and tens of millions of radar meteors."

Once again, right now no one knows the parent populations of either asteroids or comets with much certainty.
 
"The Earth environment models are presumed to describe quite well both the shadowing and focusing effects of the Earth and Moon on each other."

Actually, we're dealing with indeterminate equations, and will be until more cratering data comes in from other bodies in our solar system. Including some ideas as to what hit, whether asteroidal or cometary.

As a brief demonstration of my assertion, consider that based on Moon data Morrison set the ELE rate at 1 per 100 million years, when it is 1 per 26 million years.

QED, Chris.
Ed
Received on Mon 04 Jul 2011 09:02:17 PM PDT