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Martian Gullies Explained By ... Sand
eldavojohn writes "There's a lot of evidence that a very long time ago some fluid once flowed on Mars, but the primary evidence of water today — gullies inside craters — is explainable by a much less exotic reason: flowing dust and sand. It would now seem that the news from 2006 that NASA had found definitive evidence of flowing water on today's Mars needs to be comprehensively reexamined. The Bad Astronomer lays claim that flowing sand and dust doesn't explain all recent hi-res imagery from the red planet, but it certainly does seem more plausible, considering what we know about Mars."
That's what the Martians want us to think. Next they're going to try and contaminate our precious bodily fluids.
Oh yeah, smart guy? Then answer this:
WTF do the Martians drink?
Caveat Utilitor
Have they found the soundstage on mars where they faked the moon landing?
Mass is not the issue; the lack of a magnetosphere is. Without a magnetosphere, the solar wind will strip the atmosphere, leaving you in the same state. We would need to provide some means of creating a field which shields the atmosphere from solar winds.
Did a quick google to find an article - this one was published in 2010: http://science.nasa.gov/science-news/science-at-nasa/2001/ast31jan_1/
Forget water. If you want to create a space stampede to Mars, announce the discovery of oil there.
Take those photos that the various missions have taken of Mars, and use the photo analysis software that CSI uses. You should be able to look at things down to a molecular level then. Even a photo taken with a disposable camera that happened to be pointing in the direction of Mars during a stormy night should be sufficient to determint the location of all water on Mars. They could look at the back side of Mars based on a reflection from one of the stars behind it, so you should easily have 360 degrees of visibility..
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
Nutrition Facts: Mars Bar
Calories: 220
Sodium: 70 mg
Total Fat: 9 g
Potassium: 0 mg
Saturated: 6 g
Total Carbs: 36 g
Polyunsaturated: 0 g
Dietary Fiber: 1 g
Monounsaturated: 0 g
Sugars: 30 g
Trans: 0 g
Protein: 2 g
Cholesterol: 5 mg
Vitamin A: 0%
Calcium: 6%
Vitamin C: 0%
Iron: 4%
Percent Daily Values are based on a 2,000 calorie diet. Your daily values may be higher or lower depending on your calorie needs.
The ESA already has a picture of water ice in a martian crater. Maybe they are talking about different types of craters in different regions, but this photo clearly shows that it is possible.
http://www.esa.int/SPECIALS/Mars_Express/SEMGKA808BE_0.html
-molo
Using your sig line to advertise for friends is lame.
If the entire Belt were diverted to Mars, it would increase Mars' mass by about 1%.
In other words, "your idea is silly"....
"I do not agree with what you say, but I will defend to the death your right to say it"
This actually hits on one of my personal bugaboos - scientists that claim to know something "definitively" while the research or hypothesis is still warm from the metaphorical oven. Unfortunately, the institutions that employ them have figured out that you can get funding through "science by press release" - the initial press release gets the headlines; the retractions are hardly noticed (except on Slashdot). The scientists themselves are certainly culpable as well for going along with this - they should know better. Only a small percentage of theories stand the test of time. Yes, I understand that it's 2010 and we all want answers right now, dammit, but 99.99% of the time life just doesn't work that way.
So anyway, "definitively" - You keep using that word. I do not think it means what you think it means.
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I love that "above some critical threshold" is listed like a mysterious or complex thing. It's the angle of repose, the angle that a material naturally sits at when you let it fall from a height and pile up. It might be, if things are very complicated, the angle of repose + cohesion, but then you're back at water-based theories again since water is the easiest way to remove cohesion and trigger failure.
I also really like that the experimenters managed to recreate a sand flow in their lab. Of course they did. The field of prior research involving laboratory sand flows is immense, especially if you start including the ones with tiny glass beads of carefully varied diameters instead of sand. The only problem is thioxtropy -- landslides are renowned for having material that exhibit viscosity inversely proportional to velocity -- which is not easily replicable in small-scale lab settings.
I'm not sure if this is a, "Physicists discover what geologists already knew" moment, or a "Journalists are puzzled by the mundane mysteries of science," or what, exactly, but if you want to learn more about landslides on Mars, check out geotechnical journals starting with Lucchitta 1978 (Bulletin of the Geological Society of America, v89, pg 1601) and work your way forward. As the lunar and Martian landslides discredited an entire set of excess mobility theories, they're very well described and discussed.
You don't read the science news stuff very often (or ever), do you...
NASA has definitely found water on Mars already.
They also found a number of minerals in the rocks that can only form in water, as far as we know.
True, that as far as we know bit means it could be something else, but let's stick with known laws until we have evidence of something else before jumping of the cliff labeled "It's got to be caused by an unknown means". Don't forget Occam's Razor. (Especially when the alternative is trying to choose between Known Science and Baseless Denials.)
Does this mean the dust & sand thing is wrong? Not really, but it doesn't mean that water is out either. Funny thing about places that change environments, their primary methods of erosion change as well. Just look at Egypt over the past 30,000 years as a small example.
Thanks
From the original blog post : "over this timescale, the Martian atmosphere has been too cold and thin for liquid water."
I read something like this frequently, and yet it is simply wrong and I wish people would stop repeating it.
Liquid water is not magic, but governed by physics. For there to be liquid water on Mars, all that is needed is that water be present, that the surface pressure be above the triple point of water, and that the temperature be above the freezing point. (Actually, this can be relaxed somewhat for brines and the like, but let's put that aside for the moment.) We know that Mars has water. What about the other two conditions ?
Much of the surface of Mars is above the triple point of water (i.e., at a low enough elevation that the surface pressure is higher than 611.7 pascals). Any low lying region is. The Viking 2 landing site is (some of the time) and the Phoenix landing site is (all of the time). The entire Hellas basin is, and it is highly likely to have liquid water at times (as the surface temperature there is warm enough during the day). Remember, peak surface soil temperatures on Mars can reach 27 C, even under current climate conditions.
Further, the atmospheric pressure on Mars varies greatly during its obliquity cycle, and it is highly likely that the entire planet (except for the high volcanoes of Tharsis) can support liquid water at times during each obliquity cycle. During those phases of the cycle, the atmospheric temperatures will be generally warmer, as well.
Now, this does not prove or disprove that these gullies are formed by water rather than sand, but you don't need unusually strong brines or geothermal vents to have liquid water on Mars (even though both of those probably exist as well), and it is quite reasonable to expect its presence in places, even under current atmospheric conditions.