Giant Asteroid Flattened Half of Mars, Studies Suggest

[LowlyPion]

In looking at the Martian hemispheric dichotomy (significant differences in the Martian crust over a large radius) simulations suggest that Mars was hit by something like a 1000 to 1700 mile wide asteroid about 4 billion years ago.

http://www.sciam.com/article.cfm?id=giant-asteroid-flattened

Possibly not all that long after the Earth was acquiring the moon.

It was a rough neighborhood in those days.

 

[B. Elliott]

Very interesting article LowlyPion. I especially like the animation... Thankyou for posting that. Over the past six months or so I've taken an interest in investigating possible reasons behind the formation of the Tharsis Buldge and Valles Marineris... everything from superplumes to simple global contraction. I also like how this finding sheds a bit of light on the magnetism issue. A massive impact early after Mars's formation has been suspected for a while now, but this certainly reinforces the idea.

Here are two writeups on the Borealis basin

Global Structure of the Martian Dichotomy: An Elliptical Impact Basin
http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1980.pdf

The Borealis basin and the origin of the martian crustal dichotomy Account required.
http://www.nature.com/nature/journal/v453/n7199/full/nature07011.html;jsessionid=EA28B019A7CF3A754A52AB4E3DCF69DFHere's another (somewhat related) paper which touches on the Hellas Basin impact..

Mars Impact Energy Analysis In Support of the Origin of the Crustal Dichotomy an ofther Anomalies
http://www.lpi.usra.edu/meetings/hemispheres2004/pdf/4002.pdf

I'd like to see if there are any estimates on the approximate time during the initial impact and it's relation to he approximate time of the impactor which formed Hellas Planitia.

 

[LowlyPion]

One assumes that rockhounding about on the planet would help to resolve these issues.

At the very least the idea that 1000 - 2000 mile boulders (and bigger if you consider our moon may have been another such event) bouncing about in the early solar system gives pinball a new meaning. It might have been interesting in the extreme to have been able to witness these events - of course and then be able to go home to a pleasant espresso after the show.

Thanks for the additional link to what looks like the source material for the Scientific American piece.

You might find this post-doc researcher's page at MIT of interest.
http://web.mit.edu/jhanna/www/jchanna_research.html