[meteorite-list] Earth meteorites then and now
From: MARSROX_at_aol.com <MARSROX_at_meteoritecentral.com>
Date: Thu Apr 22 09:47:10 2004
I agree with Ron that it is logical that leftover Earth (and planetary
impactor) material from lunar formation may be out there. Should it fall
(back) to Earth would it be -
3. Assuming cosmic ray dating of 4+Ga, pre-plate techtonics, how could it be
source differentiated from any other achondrite? Assuming large enough
accreted masses were leftover from the planetary impact, not a vapor cloud,
wouldn't a sample's crystal structure reveal planetary gravity greater than
Mars? Wouldn't that be an obvious clue? Wouldn't some early-Earth trapped
atmospheric gases with a strange fingerprint raise eyebrows?
4. Could some of the existing weirdo, anomolous meteorites i.e. brachinite,
Divnoe-types actually be from Earth?
Secondly, short of the planetary bump on Earth that seemingly dislodged
material that formed our moon, what other theoretical event could later knock
rock off of this planet without destroying the planet? The "Mars example"
oblique impactor/ejector theoretically allows for a 10 km/sec velocity for an
impactor (what size?) able to "push" material beyond Mars' 5 km/sec escape
velocity with minor effect from atmosphere drag. In the "Earth case", we have
the same average 10 km/sec impactor (of what size?) needing to push, not
vaporize, material past the Earth's escape velocity (is it 8 km/sec?) plus
overcome ablating atmosphere on the way back up to space. I don't think that
the material could retrace a possible vacuum left by the impactor since
existing theory suggests that only a glancing, oblique impact, not a direct
hit, is capable of ejecting (not vaporizing) material into space.
Only tektites need apply?
In the category of "small world, isn't it", I just returned from a couple of
weeks in the Dominican Republic. The rum's just OK, but you can't buy a bad
cigar. Four girls I met at a sushi bar told me they were from Queens. It's
not unlikely that they flew back on the now-downed Airbus two night's ago
How would YOU feel? Gulp.
Received on Mon 12 Nov 2001 05:42:37 PM PST