Devils & Dunes

Heh, cool pictures. But i wonder, how powerful are they? I hope that they couldn't tear a hab or greenhouse apart ! What would happen to an astronaut if he gets caught in a dust-devil ?

*Hi BGD. If I recall correctly, similar questions were asked a long time ago (summer 2002) and I'm pretty sure the input on it was that because of Mars' low air pressure, dust devils aren't that powerful and don't present an extreme danger. I think someone (Phobos or Shaun?) said a dust devil might push you around abit if you were caught in one, but not necessarily knock you off your feet. That's to the best of my recollection.

--Cindy

Palomar · 2004-01-15 08:33:31

Hmmm, it would be nice to have a few hundred strong weather probes on the martian surface, with some small Doppler radars integrated, to measure air speed and detect humidity, radiation detector, retractable solar arrays, powerfull batteries, etc., and a network of orbiting satellites, with integrated GPS. Yummy.

*I'm a weather watcher, so yeah -- that'd be great.

Forgot to mention in my previous post that Marsian dust devils can grow to a height of 8 kilometers. Whoa!

As for one of them knocking around a rover or a lander; the smaller ones, perhaps. Spirit and Opportunity both weigh over 200 pounds, IIRC. I think they'd be safe enough (once Opportunity gets there of course...next week). It'd be cool if a dust devil breezed right over Spirit, huh? That'd likely provide some interesting feedback. :laugh: But given the size of Mars versus that little rover...it's probably a long-shot it could happen.

--Cindy

Palomar · 2004-02-13 08:13:58

[=http://www.spaceref.com/news/viewsr.html?pid=11844]Sand Dunes in Noachis Terra

*Very distinctive dunes...I wonder how tall they are.

"Most big martian dunes tend to be dark, as opposed to the more familiar light-toned dunes of Earth. This difference is a product of the composition of the dunes; on Earth, most dunes contain abundant quartz. Quartz is usually clear (transparent), though quartz sand grains that have been kicked around by wind usually develop a white, frosty surface. On Mars, the sand is mostly made up of the darker minerals that comprise iron- and magnesium-rich volcanic rocks..."

---

[http://www.spaceref.com/news/viewsr.html?pid=11845]Desert Island

*A big bump out of nowhere. Very striking (and reminds me a bit of some of the more weird geographical anomalies in my neck of the woods).

--Cindy

P.S.: Maybe that first pic is REALLY a Marsian "SOS"...you know some sort of language/communication using sand! :laugh:

dicktice · 2004-02-13 09:30:40

Cindy: Thanks for all the pictures showing dust devils on Mars. How the heck did you acquire them--I'm so dumb reqarding such acquition techniques, and too old (and lazy) to learn 'em on my own. But, one thing I'd like to offer, regarding flying on Mars. I've flown sailplanes a lot in the desert, and down where the thermals are strong and narrow enough to raise dust a few thousand feet . . . you keep away from 'em if you want your sailplane to stay together!
But, I'm inclined to think spiraling inside those dust devils you've shown, could become the established means of "staying up" to save power on Mars, in self -launching (means of power and propulsion to be determined) sailplanes especially designed for the air density and gravity strength there. Soaring the Thermals of Mars: that has a nice ring to it, don't you think?

Palomar · 2004-02-13 09:38:11

Cindy: Thanks for all the pictures showing dust devils on Mars. How the heck did you acquire them--I'm so dumb reqarding such acquition techniques, and too old (and lazy) to learn 'em on my own. But, one thing I'd like to offer, regarding flying on Mars. I've flown sailplanes a lot in the desert, and down where the thermals are strong and narrow enough to raise dust a few thousand feet . . . you keep away from 'em if you want your sailplane to stay together!
But, I'm inclined to think spiralling around those dust devils could become the established means of "staying up" on Mars, in self -launching (means of power and propulsion to be determined) sailplanes especially designed for the air density and gravity strength there. Soaring the Thermals of Mars: that has a nice ring to it, don't you think?

*Hi dicktice:

I got the images from Google: [http://www.google.com]www.google.com; click on "Images" feature; type in the words Mars dust devil; hit "Enter."

That's how I got the photos.

Yes, I like the sound of "Soaring the Thermals of Mars" (I don't know much about flying though [sailplanes or anything else]). Spiralling around dust devils? That sounds like fun.

--Cindy

dicktice · 2004-02-13 17:33:24

If there's a "Las Cruces Soaring Club" give 'em a call, because I suspect you have plenty of big dust devils out west, where you live.

Shaun Barrett · 2004-02-13 18:31:54

Nice pictures, thanks Cindy!

I'm not quite sure about this but I think the long dark features often associated with dust devils in these images aren't shadows (I could be wrong).
I think they may be long tracks where the dust devil has cleaned lighter surface dust away from the underlying darker material.
???

Palomar · 2004-02-14 05:49:47

Nice pictures, thanks Cindy!
I'm not quite sure about this but I think the long dark features often associated with dust devils in these images aren't shadows (I could be wrong).
I think they may be long tracks where the dust devil has cleaned lighter surface dust away from the underlying darker material.
???

*Hi Shaun:

You're welcome. In a few photos, white arrows point out both the track and the shadow. As for unmarked photos...your guess is as good as mine. :;): Some of the alledged shadows are rather dark...I've wondered if the Marsian dust devils are really that dense, to cast such a dark shadow (I don't recall dust devils around here casting shadows; of course this is 2 entirely different planets we're talking about with different atmospheric conditions...) ... hmmmm ... now you've really got me wondering! :laugh:

*Hi Dicktice: Yes, we have big dust devils. I've seen a few so well formed they look like ghostly tornadoes (perfect cones), etc. There is so much peripheral development around the city, however, that dust devils are few and far between anymore (to be seen or encountered in or near town)...same goes for roadrunners, unfortunately.

--Cindy

::EDIT::

A few months ago I posted a similar image (from Astropix; the one below is courtesy Space.com) somewhere here at New Mars (I forgot where, lol). Anyway, good info accompanies the truly bizarre pic (IIRC, Astropix displayed the photo with the trails running horizontally). I seldom repeat info here, but this is a worthy exception (bizarre!!...looks like capillaries and a blood vessel in old b/w anatomy books I've seen). There is also a link to an article entitled "Dust Devils Reshape Mars" at the bottom:

[http://www.space.com/imageoftheday/imag … 31222.html]Devilish Mars

dicktice · 2004-02-14 09:51:00

Coincidentally, while Googling today, as Cindy recommends, I stumbled upon the following item about dust devils, with an implied suggestion re. possible soaring flight on Mars.

Spirit's temperature profiles were derived from data taken by the mini-Thermal Emission Spectrometer, which was primarily intended to study the mineral composition of soil and rocks.
But Cornell University scientist Don Banfield and Michael Smith of NASA's Goddard center, members of the science team, figured out an ingenious scheme for taking Mars's temperature profile. This began with setting the mini-TES camera to stare steadily at a patch of sky about 30° above the horizon for several minutes.
They had known it would be possible to derive an estimate of atmospheric temperature by studying the infrared spectral lines associated with carbon dioxide, the primary component of Martian air. But it was not until they started studying the actual data that they realised they could get much more.
Carbon dioxide absorbs one particular infrared wavelength well, with the absorption proportional to its density. In turn, density is proportional to altitude - the air gets thinner higher up. Finally, the shapes of the spectral lines correlate with temperature.
So putting everything together, it is possible to tease out a plot of temperature versus altitude. "We hadn't really thought about that until we got to the surface," Banfield happily admits. Taking day-by-day temperature profiles should give atmospheric modellers a fascinating look at the dynamics of Martian weather.
The new data show very rapid fluctuations in the air temperature. In the morning, the air 30 metres up can fluctuate up or down by as much as 4°C in a single minute. This is caused by pockets of air near the ground being warmed by the Sun and rising rapidly.
Such "thermals", common on Earth and harnessed by soaring birds and hang-gliders, have never been detected before on Mars.
The new data stretches up to at least a kilometre and could help the designers of future spacecraft to compensate more accurately for the winds that buffet landers during their descents.
The European Space Agency's orbiter, Mars Express, will also soon be examining the temperature of the Martian atmosphere, but on a global scale. It will use its SPICAM ultraviolet and infrared wavelength instrument to measure profiles of temperature, carbon dioxide, ozone, dust and clouds.

How about that for good timing?

Visited by Moderator 2022/03/08

Palomar · 2004-02-17 10:22:33

*Some of the gems I've picked out in the article below (mentioned previously):

[http://www.space.com/scienceastronomy/s … 702-1.html]http://www.space.com/science....-1.html

"...sometimes the dust devils are so big that you can see them with the wide-angle cameras meaning that --->they are wide enough to cover a couple football fields<--- and stand several kilometers high..."

*I knew previously they could grow quite high...but "wide enough to cover a couple football fields"?! I didn't know that! Wow.

Apparently Viking landers detected vortices on Mars, and there's this (reminded me of BGD's comment/question earlier):

"...Similar detections occurred during the 1997 Mars Pathfinder mission. --->Some of these went right over the lander without causing damage<---..."

*Regarding devil shadows and bent devils:

"...Because the camera is looking straight down, the shadow is what gives the best impression of the shape of the thing. Bent dust devils like this aren't unusual, but neat nonetheless. --->The bending is caused by differences in the wind at different levels in the lower Martian atmosphere at the time the dust devil was moving across the landscape<---."

*Devils in the pink?:

"Dust devils may contribute some of that dust that gives the sky its pinkish color."

*Article goes on to state that dust devils are "very common all over Mars"...including this amazing tidbit:

"It surprises me that we even see their streaks at the top of the giant volcano, Olympus Mons, where the atmosphere is so thin---about 10 times thinner than at the Mars Pathfinder site--that you are almost in a vacuum..."

*Devils at the top of OM??? My god! That is fantastic.

Wonders never cease...

--Cindy

Shaun Barrett · 2004-02-17 18:41:12

Those streaks at the summit of Olympus Mons interest me for slightly different reasons.
Apparently there are also crater-free dune fields at the summit, which means they're young. But the 1 or 2 millibar air pressure at that altitude is insufficient today to move dust and sand into large dune shapes.
In another thread here somewhere, I speculated that the martian atmosphere therefore may have been considerably thicker in quite recent times; perhaps as much as 30 or 40 millibars at datum. Given that Mars' atmosphere is 'taller' than Earth's for gravitational reasons, the pressure on Olympus may get to 8 or 10 millibars in such a periodically denser atmosphere(?)

These dust devil streaks may be one more piece of evidence to suggest Mars really does have a 'pulsating atmosphere', which swings between, say, 6 and 40 millibars at datum on a time scale of thousands of years or even less. If this were true, it would help to explain some of the channels and dry river valleys which look recent; they may have liquid water in them for centuries at a time but happen to be bone dry at present.

This is a testable hypothesis in as much as we can make periodic observations of the Olympus summit and search for active dust devils and significant changes in the dunes.
If we find no such activity over some years of observation, that will strengthen the argument.

[Now tell me they have photos of active dust devils on Olympus!! ]

Palomar · 2004-03-17 07:10:13

[Now tell me they have photos of active dust devils on Olympus!! ]

*I wish I could.

[http://www.spaceref.com/news/viewsr.html?pid=12229]Click

Interesting shadowing effect on these dunes [Kaiser Dunes]. Mentions devil trails as well.

By the way, Spaceref.com hosts a daily photo of Mars. This one was taken last month and recently released.

--Cindy

Palomar · 2004-03-27 06:49:13

[http://antwrp.gsfc.nasa.gov/apod/ap000317.html]Looks like crayon scrawlings which a toddler might make. I get the impression one of the dust devils may have stood still, "grinding" for a few moments, given that blot-shaped mark. I found this in the Astropix archives. Check out the very fine but marked ripples running catty-corner to the photo. This is really a remarkable image.

[http://antwrp.gsfc.nasa.gov/apod/ap000202.html]More devil tracks

--Cindy

rgcarnes · 2004-03-30 09:11:49

Has anyone seen a mathematical model of a "dust devil" phenomenon on Mars which includes energy transfers and heat capacities of the involved dusts and gasses?

I sincerely doubt that "dust devil" is a properly descriptive term when one considers the energies involved, although I'm certain dust may be entrained in the process.

Tornado may be a more descriptive term as I suspect H2O phase changes are the only reasonable means of such large energy transfers just as tornados are powered on this planet.

Many of the "dust devil" images show a tendency for them to originate at darker features which may be vents for H2O vapor. Please study the images carefully.

Palomar · 2004-04-04 20:50:54

*Hi Rex. Wish I could answer your questions... Involves math? You really *wouldn't* want my help. :;):

[http://www.spaceref.com/news/viewsr.html?pid=12442]How convenient; just the other day I was wondering if dust devils -are- literally all over the planet, i.e. in the polar regions. In the link above are tracks -- many tracks -- in the south polar region [according to the article].

I'm not all that great with longitude [or latitude for that matter]; about how far south were the tracks made, according to the coordinates given at the site ["This picture is located near 64.6°S, 340.5°W."]? An estimate in miles or kilometers from the south pole is what I'm hoping for.

Input would be appreciated; thank you in advance.

--Cindy

::EDIT:: Regarding your comments that they would more aptly be called "tornados", here's Webster's definition (for my own benefit, since I want to be very precise):

"A rotating column of air ranging in width from a few yards to more than a mile and whirling at destructively high speeds, usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud."

I always associate the word -with- extension from a host cloud, but...?

"Dust devils" is a much more charming name. :;):

SBird · 2004-04-04 23:24:04

ecrasez - it's not too hard to calculate that distance, really. Basically, 64.6 degrees latitude means that you're 25.4 degrees away from the S pole. Mars is 21,300 km in circumference. The distance from the S pole to your point is that circumference times 25.4 degrees divided by 360 degrees. Therefore the distance is ~1503 km.

Palomar · 2004-04-06 08:03:02

ecrasez - it's not too hard to calculate that distance, really. Basically, 64.6 degrees latitude means that you're 25.4 degrees away from the S pole. Mars is 21,300 km in circumference. The distance from the S pole to your point is that circumference times 25.4 degrees divided by 360 degrees. Therefore the distance is ~1503 km.

*Thanks, SBird. As for making those sorts of calculations, well...some of us are a bit mathematically impaired. :-\ (Otherwise I'd be a professional astronomer).

I still am intrigued by Rex's comments: "Tornado may be a more descriptive term as I suspect H2O phase changes are the only reasonable means of such large energy transfers just as tornados are powered on this planet.

Many of the "dust devil" images show a tendency for them to originate at darker features which may be vents for H2O vapor."

*Anyone want to chew on this? I admit I hadn't previously taken especial note of dust devils having, according to Rex's eye, a tendency to originate at darker features. He's got me wondering...!

--Cindy

Palomar · 2004-04-15 06:18:27

[http://www.space.com/imageoftheday/imag … 40415.html]Oooooooooo

*Taken by MGS in January near the north pole, released yesterday. Wow, magnificent. Check links at the bottom of the article.

--Cindy

::EDIT:: [http://www.space.com/imageoftheday/imag … 30918.html]"Martian Gray Matter" It -does- look like brain tissue, doesn't it?

[http://www.space.com/scienceastronomy/m … 31110.html]"Dizzying Heights" Up to 20 feet tall! Hopefully I haven't posted this article previously; I don't recall. If so, not intentional of course.

Palomar · 2004-04-20 10:21:17

[http://www.nasa.gov/home/hqnews/2004/ap … _dust.html]The Electric Psychedelic Whirling Dust Devil Lounge

*Yeah baby! That's what I'm going to name my '60s-style hang-out joint on Mars! :laugh:

Says the track patterns change from season to season. Now that's interesting in and of itself. Scientists have found clues that Marsian dust devils might have high-voltage electric fields. Lots of other goodies in the article too.

--Cindy

::EDIT:: "However, the team's observations indicate smaller particles become negatively charged, while larger particles become positively charged. Dust devil winds carry the small, negatively charged particles high into the air, while the heavier, positively charged particles remain near the base of the dust devil. This separation of charges produces the large-scale electric field, like the positive and negative terminals on a battery. Since the electrified particles are in motion, and a magnetic field is just the result of moving electric charges, the dust devil also generates a magnetic field."

dicktice · 2004-04-20 14:37:47

As a glider pilot out in the desert, I learned to avoid dust devils below 1,000 feet above ground, as being too narrow and violent to circle in safely, but on Mars--especially with a mag-field to utilize--one might imagine robot gliders centring with these broad columns of air by means of differential magnetic pickup heads on their wingtips. "Thermal detectors" have been the dream of glider pilots since flight perofrmance made soaring flight in so-calle dry thermals feasible, with little success. Electrostatic field strength was a flop (too ambiguous) and sensitive rate-of-climb/sink indicators too after-the -fact. Gosh, Mars has a lot to teach us, and we ain't even there in realtime, yet.

Palomar · 2004-05-26 08:43:12

http://antwrp.gsfc.nasa.gov/apod/ap000317.html]Looks like crayon scrawlings which a toddler might make. I get the impression one of the dust devils may have stood still, "grinding" for a few moments, given that blot-shaped mark. I found this in the Astropix archives. Check out the very fine but marked ripples running catty-corner to the photo. This is really a remarkable image.
http://antwrp.gsfc.nasa.gov/apod/ap000202.html]More devil tracks
--Cindy

*After weeks of rocks and boulders :sleep: , I decided to go on a dust-devil hunt, see if any new images of devils and/or their tracks have been turned up recently (by -any- of the probes/satellites currently at Mars). I found essentially no new images, although I will search Google a bit more extensively.

In the meantime, I turned up these 2 items:

http://www.the-planet-mars.com/dust-sto … .jpg]Devil scrawlings, which I think is a much wider-range shot of the smaller area shown in the first link in the quote box above.

http://www.the-planet-mars.com/dust-sto … ged.jpg]An image I've not seen before...(unless it's a close-up of the previous pic; could be, hard to tell for sure) includes measurement.

::edit:: "Some streaks are straight and narrow, others are curly arcs, twisty, and loopy." I like the loopy ones, definitely. Especially when I'm feeling a bit loopy myself!

Now back to scouring Google...

--Cindy

::EDIT:: http://www.msss.com/mars_images/moc/lps … 6.gif]Very faint dust devil tracks

I've -not- seen that pic before.

Here's some bits of info from the sites: "They often cross over hills, run straight across dunes and ripples, and go through fields of house-sized boulders." -and- "What is 8 kilometers (5 miles) high, forms in the mid-afternoon, and cannot be found the next day?"

Form in the mid-afternoon.

REB · 2004-05-26 11:19:54

In my travels around Mars , I have found the Argyre Basin is a great place to hunt for dust devil tracks.

Here is a wonderful example.
http://www.msss.com/moc_gallery/e07_e12 … 02442.html

To get these vortex, you need a warm and cold air mixing. A good place for this is around hills or craters. That is why many dust devil tracks start at hills or craters. See about ¾ the way down the full sized imaged linked on this site http://www.msss.com/moc_gallery/m07_m12 … 01206.html or in this one http://www.msss.com/moc_gallery/e13_e18 … 00400.html

Check out this dust devil;

http://www.msss.com/mars_images/moc/may … 00/layers/

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