[meteorite-list] Earth Impacts & Soft Landings

From: chris sharp <casper_at_meteoritecentral.com>
Date: Thu Apr 22 09:52:09 2004
Message-ID: <004101c23f2d$74997f10$b5012bca_at_ringtail>

Hello all from Terra Australis

I recently downloaded an interesting article on impact cratering, 130
pages with lots of images and discussion on the current science.

http://www.lpi.usra.edu/publications/books/CB-954/CB-954.intro.html

As all members realize Earth has been impacted many times in the past
and this article points out that these impacts have shaped the earth
and its biology much more than was realized in the past. The article
points out most of the craters have been discovered in the last 50
years.

I have a question for the list:

Is it possible that a large body with cosmic velocity could have a
"soft touchdown" on Earth? ie not come in 25km/s and be explosively
disintegrated by the enormous kinetic energy that comes with such a
large, high speed mass.

I could imagine a situation where the relative velocities between an
impactor and the Earth were <1 km/s so long as the impactor approached
on the same track as the Earth's orbit around the sun.

eg Earth's velocity vector is 30km/s, impactor's velocity vector is
30.5 km/s in the same direction as the Earths leading to a net 0.5km/s
which would remain relatively constant as it "drifted" in, leading to
a relatively "soft landing".

One example might be the monolith Ayres Rock in Central Australia.

chris sharp
(not sure of the current exchange rate but its not getting any better)
Received on Thu 08 Aug 2002 06:46:37 PM PDT