[meteorite-list] Meteorite Found On Mars Yields Clues About Planet's Past

[Michael Fowler]

> August 10, 2009
>
> Dwayne Brown
> Headquarters, Washington
> 202-358-1726
> dwayne.c.brown at nasa.gov
>
> Guy Webster
> Jet Propulsion Laboratory, Pasadena, Calif.
> 818-354-6278
> gay.y.hill at jpl.nasa.gov
>
> RELEASE: 09-186
>
> METEORITE FOUND ON MARS YIELDS CLUES ABOUT PLANET'S PAST
>
> PASADENA, Calif. -- NASA's Mars Rover Opportunity is investigating a
> metallic meteorite the size of a large watermelon that is providing
> researchers more details about the Red Planet's environmental
> history.
>
> The rock, dubbed "Block Island," is larger than any other known
> meteorite on Mars. Scientists calculate it is too massive to have hit
> the ground without disintegrating unless Mars had a much thicker
> atmosphere than it has now when the rock fell. ...........


A little slow to respond to this, but it's been bothering me for some  
time.  How can they say with such certainty that it could not survive  
intact?  And from there to jump to the conclusion that the only  
possible explanation is that it must have fallen when Mars had a much  
denser atmosphere.  I disagree.  It could have fallen on a glacier, or  
maybe a sand dune, or maybe at an oblique angle on the side of a major  
hill, or ravine that has worn away in the millions, or billions of  
years since it fell.

Here's one for you.  What about the Hoba meteorite?  My guess is that  
the very same models that prove that the Block Island Mars meteorite  
couldn't have landed intact in Mars's atmosphere would also predict  
that the Hoba meteorite couldn't land intact on Earth.

Any comments?  Sterling, what do you say?

Mike Fowler
Chicago