Rovers on Mars

@farmerman,

When it comes to windblown, on Mars you're only talking about fines. The atmospheric density on Mars is so low, the highest winds won't pick up grains of sand. The fines that get blown around there are about micron sized. At any event, it's the issue of ancient water which interests me. If Echus Chasma was once a lake, Kasei Valles is the obvious natural outlet.

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Unfortunately, my search skills aren't good enough to get anything more than a descriptive "blurb" from JPL. This accompanies one of their image files (a file too big for this page):

Quote:

Echus Chasma forms the boundary between the Tharsis volcanoes to the west and Lunae Planum to the east. This region is one of both tectonically fractured rocks (top of image) and volcanic flows (middle and bottom of image). Echus Chasma empties into Kasei Valles.

The use of "empties into" is interesting--but that could just be poor writing. I wish i could find something at JPL which would tell why they say that the floor of Echus Chasma is covered in clay. I'm certain they haven't been there, in the sense of a rover having visited the site.

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@Setanta,

It certainly was a debouch point. It was an embayment that can easily be seen to have once contained water. The " chemical "Bathtub ring" is kinda visible from the spec photos an thats evidence enough, as is the coalescing sense of the interdistributary segments of what were once linear fast running streams with high energy.
The thing that most hammers down what means of trqnsport we are lookin at is bqsed upon how long qgo was the water actually there

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@Setanta,

I was doing some hunting the JPL pictures and they have plenty of dune deposits and examples of barchans all over the plqnet > So the Hjulstrom equation that pertain to energy distribution actually dictate that its more difficult to get fines to move than larger particles. Its counter intuitive but fines actually have a greater cohesion strength than larger particles . Thats why loess deposits build up at xtremely steep angles and are deposits of layered silt/clay v sand sized particles.

We hve to know what is the v of the wind that blows to see how stuff is scattered about.

The dune photos (and more classical barchans) show a sharp crest on a long dune crest .

Didnt mean to turn this into a seminar on geomorphology but heres a whole collection of dune shots. NOT ALL ARE from MARS. Many are examples from earth geomorphology

https://www.google.com/search?q=fields+of+sand+dunes+on+mars&rlz=1C1VFKB_enUS630US633&espv=2&biw=1562&bih=771&tbm=isch&imgil=8_DDNsyfTSOweM%253A%253BuWfN6YcQVGym8M%253Bhttps%25253A%25252F%25252Fsimotron.wordpress.com%25252F2012%25252F11%25252F09%25252Fdune-field-inside-endurance-crater-mars-opportunity-rover-nasajpl-caltechmichael-bensonkinetikon-pictures-august-27-2004%25252F&source=iu&pf=m&fir=8_DDNsyfTSOweM%253A%252CuWfN6YcQVGym8M%252C_&usg=__Y7ifBSvg-Ebf9s1_hc_69GeUGQ4%3D&ved=0CCgQyjdqFQoTCL7J1vKH98gCFcpWPgod7XAFhw&ei=SCE6Vr6FA8qt-QHt4ZW4CA#imgrc=8_DDNsyfTSOweM%3A&usg=__Y7ifBSvg-Ebf9s1_hc_69GeUGQ4%3D

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Well, you don't get sand storms on Mars, you get dust storms. I have read that the storms are fines, but i don't claim any expertise on that. Atmospheric pressure in the northern hemisphere (where Echus Chasma and Kasei Valles are located) runs from about 10 millibars to 12 or 13 millibars. That's one bar less than earth at mean sea level (1013 and a fraction millibars). Wind velocities run from 200 kph to as much as 600 kph (200 to 300 kph is most common)--which isn't much given the extremely low atmospheric pressure. If you had a large enough target, like a hydrogen balloon, it might get pushed around a good deal. Sand? no way.

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This is from NASA's "Mars Home" set of pages. They make a liar out of me, saying wind speeds reach 60 mph, which is only about 100 kph.

Quote:

It is unlikely that even these dust storms could strand an astronaut on Mars, however. Even the wind in the largest dust storms likely could not tip or rip apart major mechanical equipment. The winds in the strongest Martian storms top out at about 60 miles per hour, less than half the speed of some hurricane-force winds on Earth.

Focusing on wind speed may be a little misleading, as well. The atmosphere on Mars is about 1 percent as dense as Earth's atmosphere. That means to fly a kite on Mars, the wind would need to blow much faster than on Earth to get the kite in the air.

"The key difference between Earth and Mars is that Mars' atmospheric pressure is a lot less," said William Farrell, a plasma physicist who studies atmospheric breakdown in Mars dust storms at Goddard. "So things get blown, but it's not with the same intensity."

They tip a nod to your remark about the cohesion of fines:

Quote:

Mars' dust storms aren't totally innocuous, however. Individual dust particles on Mars are very small and slightly electrostatic, so they stick to the surfaces they contact like Styrofoam packing peanuts.
"If you've seen pictures of Curiosity after driving, it's just filthy," Smith said. "The dust coats everything and it's gritty; it gets into mechanical things that move, like gears."

The possibility of dust settling on and in machinery is a challenge for engineers designing equipment for Mars.

This dust is an especially big problem for solar panels. Even dust devils of only a few feet across -- which are much smaller than traditional storms -- can move enough dust to cover the equipment and decrease the amount of sunlight hitting the panels. Less sunlight means less energy created.

You might enjoy perusing the Mars pages on dust storms. (Clickity-click)

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@Setanta,

Quote:

This dust is an especially big problem for solar panels. Even dust devils of only a few feet across -- which are much smaller than traditional storms -- can move enough dust to cover the equipment and decrease the amount of sunlight hitting the panels. Less sunlight means less energy created.

Sounds like another case of using the wrong power source.

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@Setanta,

sand doesnt ride in huge storms , even on earth. All the storms of the 30's were primarily dust. Sand just sorta skips along the ground in patterns called saltation. If the winds get really high the sand can skip higher and higher . Sand dunes are built by sand just snaking along and saltating along the ground. Dust, when carried in the column driven by winds, becomes a "fluid" which can carry particles larger than stuff in the micron level.

You need to look at the pictures of sand dunes on Mars, and tell them that they cant happen.

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@farmerman,

Heres a neat MARTIAN sand dune that apparently cant happen .obably martians shoveled it on top of the basement soils

http://gadgets.ndtv.com/science/news/nasa-maps-sand-dunes-on-mars-751421

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@farmerman,

Im really amazed at how dumb the JPL geologists seem to bve. I found lots of pix of sand dunes as I suspected. The JPL geologists were "Surprised " because of Mars "thin atmosphere"

Im notcriticizing how Set misunderstands the transport mechanics of sand , but a trained geologist should know better. Must be a bunch of grad students doing internships.

When a wind storm kicks up DUST . The "lifting capacity " of the "fluidized dust" is actually a function ore of the DENSITY and viscosity of the dust (Think of it as a mud slide where the lifting capacity is a function of specific math laws governing how **** moves in wind and water.

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NASA today put out a call for more astronauts to get ready for going to Mars. This is after they have lost a ton of astronauts since the Shuttles stopped (just under 150 before the announcement of the end of the shuttle to 47 now) because there is nothing to do and no likelihood that there will be anytime soon. I feel sorry for the people of fall for the Mars sales pitch, at best they will be confined to low earth orbit as we have since 1972. Maybe we get back to the moon or do that asteroid near the moon but given the lack of interest and how all recent manned programs have been cancelled before they are completed call me skeptical.

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@farmerman,

It's entirely possible that the JPL folks lack the specialization. When i referred to high wind speeds which the JPL page contradicts, i was referring what i had read in a university library in the late 1990s--i believe in the Proceedings of the IAU. Apart from the fact that we probably have newer, more accurate data, astronomers don't necessarily do meteorology or geology. At the same time, i'm not confident that geologists automatically qualify as areologists.

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@Setanta,

yeh youre right abvout that. We hire guys like that because theywant the Most Appropriate Skills and training in remote sensing and air photo analyses is still not a universal skill set that all schools and labs train for.
A lot of the analyses is being done by pattern recognition by computers and what they may need is to get some old oil field guys with eyeball experience, or even ARCHEOLOGISTS doing reserach in Central America or Middle East. Those guys have seen em all

BUt I tell ya, I learned a whole lot about the catalog of the MArs backup photo data that your posts spurred me to look into. Im amazed at the stuff they have on file. Its damn amazing how they have broken up the photo segments into these visual data sets. I hope the USGS publishes some compilations of data analyses for many of these.

I am now really stoked to see more of the shots surounding these plains and that really nifty distributary set of (apparently fracture formed vallies that became water discharge points.

It was in the Valles Marineris (I was calling it VAlles Marinara).

I do know that GSA is planning to pub a photo recon catalog for all these many geo features. and they have it from Rovers , overhead. AND low oblique photos.
Awesome stuff.

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@farmerman,

When the Tharsis plateau was thrust up (so the theorizing goes), it did cause a great deal of fracturing. The Noctis Labyrinthus is just south of Tharsis (a deep canyon system running south to north from about 30 degrees south to about 15 degrees south) and the western end of the Valles Marineris is just east of that.

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@Setanta,

You can see many secondary distributaries in those cuts that apparently carried huge volumes of water at one time. Nifty tracks it left.

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Here's a map of Valles Marinaris, color coded for elevation. Red for higher elevation, green and blue for lower elevation. The pimples to the upper left are two of the four giant volcanoes--in this case, Arsia Mons and Pavonis Mons. To help orient yourself, the southern rim of the Pavonis caldera (just visivle at the top edge of the image) lies on the equator.

https://upload.wikimedia.org/wikipedia/en/thumb/e/ee/Syria-Thaumasia.jpg/760px-Syria-Thaumasia.jpg

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@Setanta,

on the far left we can see what look like trellis drainage patterns.These alays indicate high energy stream flows in areas where the various rock lyers re alternatively soft and hrd strta. Also, usually trellis patterns indicate some uplift had occured . I wonder what are the other drqinge patterns tht surround the plains where the water probably collected

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@hawkeye10,

wow, lets put "Nostradamus" Hawkee in charge of all the space planning rationale.

Looks like we will have to replace Kepler becuase one of the drive motors crapped out and it cant be fine focused. Just when we were starting to get information.

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I heard this story on CBC, but have not yet been able to find anything online about this from NASA itself:

Solar winds strip away Mars's atmosphere, says NASA

Here's an artists ridiculous rendering of the process:

http://i.cbc.ca/1.3306005.1446750950!/fileImage/httpImage/image.png_gen/derivatives/16x9_620/nasa-mars-solar-wind.png

If i can find the announcement from a NASA source, i'll post that.

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OK, my brain was not working well--the right search criterion will do it every time.

Here's the NASA version of the story:

You don't need a weatherman to know which way the wind is blowing.

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