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#1 2004-09-28 07:37:15
- Palomar
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- From: USA
- Registered: 2002-05-30
- Posts: 9,734
Re: Mars Sand/Wind Question
*Okay Mars brainiacs, I have a question. Considering Mars' atmospheric pressure is lower (or weaker) than ours, considering the lower gravity, etc., approximately how strongly must the Marsian winds be consistently blowing to create the many ripples of sand we see in photos transmitted back from orbiting cameras? Sand is heavy...but then there's the gravity issue.
There are ripples of sand *everywhere* it seems...even long fields of them, and they must be somewhat tall as well for the OC's to be able to photograph them in the detail that they do (from that height).
Just curious.
--Cindy
We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...
--John Sladek (The New Apocrypha)
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#2 2004-09-28 07:53:56
- clark
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- Registered: 2001-09-20
- Posts: 6,375
Re: Mars Sand/Wind Question
http://mars.jpl.nasa.gov/MPF/science/lpsc98/1901.pdf
In a nutshell, they're not quite sure. Need more data.
Based on the Viking observations, they calculated that the environmental effects observed would require about 50 m/sec...
Here is a link to another explination:
http://hercules.geology.uiuc.edu/~hsui/ … ...s2.html
Even though Mars has a smaller surface gravity, because of the low atmospheric pressure, very large wind speeds are necessary to move dust particles and transport them across the planet. Wind speed in the Martian atmosphere was measured to exceed 200 km/hr (125 miles/hr) typically. Gusts can often reach 500 to 600 km/hr (300-375 miles/hr). Wind speed at the surface during a dust storm as measured by the Viking landers is about 30 m/sec (67.5 miles/hr). With wind speeds as high as these, there is no question that dust particles can be blown off the ground and produce dust storms.
enjoy. 
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#3 2004-09-28 08:01:53
- Palomar
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- From: USA
- Registered: 2002-05-30
- Posts: 9,734
Re: Mars Sand/Wind Question
*Thank you.
We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...
--John Sladek (The New Apocrypha)
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