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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?
Water, microbes, can we fill it with CO2, no ionosphere, how do we colonize...
Seriously. The only way to deal with Mars is to divert the asteroid belt's mass towards it to increase its mass. Force several tens of thousands of asteroids into a decaying orbit such that the mass is deposited on the planet. There's no water there, it all evaporates away without enough gravity to hold an atmosphere and enough pressure to remain liquid!
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It's a shame that our evidence for water turned out to likely be false, but that shouldn't stop us from continuing to look. We're not going to be travelling to Mars until at the earliest the '30s, so there's no real rush.
Is it potable?
I know that was the entire basis for one of the Doctor Who specials, but, do we even know how hard it would be to make it potable where it not to be drinkable?
Non impediti ratione cogitationus.
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.
That's right wiener_dudes. No water on Mars. Ever. No life ... ever. No nothing. Here, but not there. No Princess Lea no sandworms. It's empty pals ... our solar-system and galaxy. All the universe is empty except earth of everything but horror. Just us. Alone. Always.
http://antwrp.gsfc.nasa.gov/apod/fap/image/0504/WaterOnMars2_gcc_big.jpg this was really published by NASA a couple of years ago... on April 1st...
The MAFIAA is a bunch of mindless jerks who will be the first up against the wall when the revolution comes
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.
How come every announcement by NASA has you going away saying 'Ah Well." Should be called NAWA
~don't feel threatened by my pineal~
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.
I think when we determine, once and for all, that there is or is not water on Mars, then all of human suffering will come to an end. I propose that we increase taxes and spending to their very limits so that we resolve this crisis as rapidly as possible. We should divert all available resources to this matter, including seizing all ore mines and drafting of engineers to support the program. Anyone who shows any potential to be able to do math or computer science should be taken from whatever it is they are doing now and put into training for this endeavor. The people living everywhere from Compton to Harlem; East Oakland to Washington D.C., will rejoice at the wonderful benefits of having finally solved this issue, and for sure will give up all their humble possessions and dreams of escape to a better community to support this effort. In fact, we should declare war; shut down all private industry; seize all assets and take whatever additional measures necessary. A few several-billion dollar programs are not enough. We need massive spending in this area to complete this task so crucial to the very survival of the human race. Contact your Congressman NOW and DEMAND ACTION!
Is it hard posting to Slashdot while volunteering at the soup kitchen?
Gatorade - It's what Martians crave!
It means in future we can migrate to Mars. http://cleancolonpro.net/
The paper in this article is pretty interesting, but I don't think it explains the newest features seen in these gullies; the way they terminate in the sand looks more like a liquid flow than solid. I suspect that the authors can explain many gullies on Mars, but not all the gullies. There may be more than one mechanism at work here!
*** Phil Plait, aka The Bad Astronomer http://www.badastronomy.com
No soup for you!
Sand is a fluid ..... so a fluid still flows on Mars ....