[meteorite-list] Mars Rover's Meteorite Discovery Triggers Questions

[Beda Hofmann]

The first meteorite found on Mars - "Heat shield rock" - really 
raises questions. Based on its size I estimate it is approx. 6-7 
liters in volume or around 50 kg mass.

The smallest craters on Mars are just a few m in size, e.g. Fram 8 m, 
but there are smaller ones.

Has anyone a clue what the size of the projectile would be to create 
one of the smaller craters on Mars, e.g. of 5 m diameter? On Earth, 
as a rule of thumb 1/20 of the crater diameter might be used, this 
would be just 25 cm for a 5 m crater. Am I totally off? Then why did 
Heat shield rock not explode upon impact? It actually looks quite 
nice and undamaged.

Might this be an indication for a thicker atmosphere at the time of 
fall? Maybe the ratio between small impact craters and meteorites can 
be used to deduce the relative amounts of time Mars had a thin 
atmosphere as today, or a thicker one...

Beda
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Dr. Beda Anton Hofmann
Curator, Earth Science Department
Bern Natural History Museum
Bernastrasse 15
CH-3005 Bern, Switzerland
Phone +41 31 350 72 40
FAX    +41 31 350 74 99
e-mail beda.hofmann at nmbe.unibe.ch
http://www.nmbe.ch/
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