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APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 4:06 am
by APOD Robot
Image A Dust Devil of Mars

Explanation: It was late in the northern martian spring when the HiRISE camera onboard the Mars Reconnaissance Orbiter spied this local denizen. Tracking south and east (down and right) across the flat, dust-covered Amazonis Planitia the core of the whirling dust devil is about 30 meters in diameter. Lofting dust into the thin martian atmosphere, its plume reaches more than 800 meters above the surface. Not following the path of the dust devil, the plume is blown toward the east by a westerly breeze. Common in this region, dust devils occur as the surface is heated by the Sun, generating warm, rising air currents that begin to rotate. Tangential wind speeds of up to 110 kilometers per hour are reported for dust devils in other HiRISE images.

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Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 4:34 am
by Beyond
Hmm... Friday the 13th and the APOD is a dust 'devil' on the surface of mars, the planet of war. Is someone trying to tell us something, or is it a plea from mars to send them Mr. Clean to help clean the place up :?: :?:

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 4:42 am
by Magicman
a lo of wind and dust devils for "a thin atmosphere"

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 5:49 am
by bystander
http://asterisk.apod.com/viewtopic.php?f=29&t=27676
http://asterisk.apod.com/viewtopic.php?f=29&t=28211
Click to play embedded YouTube video.

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 8:41 am
by Alnilam
"...warm, rising air currents...". Is there "air" on Mars ??? ;o)

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 9:13 am
by henrystar
I am 72, and how well I remember the first two (US) flybys of Mars. The first showed nothing but a cratered surface, much like the Moon, very disappointing. But then, the second showed an interesting complex surface. How happy I am that I am still here all these decades later to look at a dust devil on Mars! The poor old Russians have never succeeded in landing anything on the Red Planet. But they are still game! And they did better than us on Venus with landers.

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 11:55 am
by jerrythebiker
Air - A colorless, odorless, tasteless, gaseous mixture, mainly nitrogen (approximately 78 percent) and oxygen (approximately 21 percent) with lesser amounts of argon, carbon dioxide, hydrogen, neon, helium, and other gases.


Nope, no "air" on Mars since it has an atmosphere composed of roughly 95% carbon dioxide. I wonder what the locals call it? :shock:

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 12:17 pm
by geckzilla
jerrythebiker wrote:Air - A colorless, odorless, tasteless, gaseous mixture, mainly nitrogen (approximately 78 percent) and oxygen (approximately 21 percent) with lesser amounts of argon, carbon dioxide, hydrogen, neon, helium, and other gases.


Nope, no "air" on Mars since it has an atmosphere composed of roughly 95% carbon dioxide. I wonder what the locals call it? :shock:
Both online dictionaries I checked included "a light breeze" as a definition for air, which suits the purpose of the APOD description. In any case, dictionaries are obviously written by overly geocentric persons. ;)

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 12:46 pm
by orin stepanek
Oops! I got to playing with Google Mars and (my how time flies when your having fun) :clap: :yes: found out the view repeats itself as you pan left and right! :mrgreen: 8-) :lol:

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 12:52 pm
by Tszabeau
What, if any, effect do the dust devils have on the topography of the region?

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 1:31 pm
by geckzilla
Tszabeau wrote:What, if any, effect do the dust devils have on the topography of the region?
They leave trails in some places.
http://www.nasa.gov/multimedia/imagegal ... _1500.html
That's as much as I can remember.

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 1:42 pm
by FloridaMike
Tszabeau wrote:What, if any, effect do the dust devils have on the topography of the region?
Kay Ryan addressed this in her poem "Blandeur" made less geocentric below...
Kay Ryan wrote: Blandeur


If it please God,
let less happen.
Even out Earth’s Mars'
rondure, flatten
Eiger, blanden
the Grand Canyon Valles Marineris,
make valleys
slightly higher,
widen fissures
to arable land,
remand your
terrible glaciers Carbon Dioxide ice caps
and silence
their calving,
halving or doubling
all geographical features
toward the mean.
Unlean against our hearts.
Withdraw your grandeur
from these parts.

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 2:04 pm
by nstahl
Great APOD, bystander great video, orin what goes around comes around.

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 2:25 pm
by Chris Peterson
Alnilam wrote:"...warm, rising air currents...". Is there "air" on Mars ??? ;o)
There is. It's pretty thin... less than 1% of the air pressure on Earth. It's mainly carbon dioxide, rather than nitrogen and oxygen like on Earth. And it's pretty cold. But it's air- substantial enough to produce meteors, to lift huge dust storms and little dust devils. (And fortunately, to blow the dust off of the rover photovoltaic panels.)

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 3:08 pm
by neufer
Tszabeau wrote:
What, if any, effect do the dust devils have on the topography of the region?
http://en.wikipedia.org/wiki/Taz_in_Escape_from_Mars wrote:
Image
<<Taz in Escape from Mars is a video game developed by HeadGames and released by Sega in 1994 for the Sega Mega Drive and Sega Game Gear featuring Taz, the Looney Tunes Tasmanian devil cartoon character. Taz must escape from Mars, where he was brought by Marvin the Martian. The game includes six worlds with two or three levels in each world.

Marvin the Martian visits his Martian zoo and finds an empty cage. He looks in his book for Earth creatures and finds Taz, the Tasmanian devil. Marvin gets the idea of capturing Taz for his zoo and heads to Earth to capture him. Meanwhile, Taz is minding his own business until Marvin beams Taz up into his flying saucer taking Taz to Marvin's Martian zoo where Taz escapes.

There are 6 worlds, each with 2 or 3 levels and a boss at the end. Each world has a set of unique challenges, many of which closely related.
  • Mars: Taz begins on Mars in the Martian zoo Marvin brought Taz to. Scattered around are teleporters to teleport Taz to different parts of the level. The boss is an alien resembling an elephant with long spines going around in circles then shooting exploding mines that bounce around.

    Moleworld: Moleworld has hunters in the form of moles. There is also dirt, of which Taz can dig into, often litered with spiky mines. The second level involves a underground mine with a mole hunter drivng a large tunnel boring machine that constantly moves forward and takes Taz's life away instantly. The boss is one of the mole hunters in a large spaceship in an area where Taz constantly falls with rocks along the way.

    Planet X: Planet X involves some flying, and a little water. The first half of the first level involves land exploration with sliding along waterfalls and fast-moving rivers at the last half. The second level is entirely extensive waterfalls with many octopus and its tentacles. The third level is entirely flying. The boss is a large green centipede-like creature with spikes covering its body making several curves and zigzags each time it comes out of the ground.

    Mexico: Having arrived back on Earth, Taz is placed on a long, fast-moving wagon train pulled by mules with occasional cows and bulls along the pathway. Falling off this causes Taz to lose health and get dragged back slowly. Yosemite Sam sometimes appears here as well with a bird flying along that drops sticks of dynamite from the air, Wile E. Coyote and Road Runner also appear. The second level involves Taz exploring a Mexican town. Yosemite Sam fires his guns wildly in two places and it is the first level that introduces going indoors. The boss is a bull fight with Toro the bull, of which Taz needs to trick Toro into slamming into the walls of the stadium.

    Haunted castle: The haunted castle is the last world visited while Taz is on Earth. The first level is outdoors. The last two levels are both indoors. The last indoor level is in a laboratory. The boss is an evil scientist with Gossamer.

    Marvin's House: Taz visits Marvin's house to find and defeat him. The first level is outside where the level is drifting along the stars. The dog, K-9, is seen in two occasions as is even twice as powerful than any boss. The second level is a laser maze where Taz must shut off four lasers in order to access Marvin. Touching the lasers causes Taz to take damage. Gravity in the laser maze level is also varies on any of four basic directions: the usual straight down, but also up, left, and right. The boss is Marvin himself in a Lex Luthor style mechanical exoskeleton.
-----------------------------------------
Controls: Taz jumps, spins, and does other various actions. By spinning and colliding with an enemy, Taz can defeat his enemies and dig into the ground. The actions can be flipping a switch, spitting a rock, breathing out a flame, or picking up something.
-----------------------------------------
Enemies: Most enemies take one hit, others take two. Most bosses take 6 to 8 hits. Only one nonboss enemy takes more than two hits to destroy. From touching an enemy without spinning, or one of their attacks, Taz loses one hit point of damage. Taz can sustain 12 hit points. Some boss enemies take two hit points and Marvin's dog, K-9, takes four hit points. Some enemies, like the fly or armored soldier (in the haunted castle world) cannot be defeated by the spin, but only by rocks or the flame. Others, like Yosemite Sam, cannot be defeated at all.
-----------------------------------------
The most common type of powerup is food. Food replenishes Taz's health. By spinning into the food, the food is destroyed. Food items include burgers (+1 hit point), bread, fruit, ham, and cakes. A special powerup is a medipack which replenishes 6 hit points if eaten, half of Taz's health. Other powerups include a box of rocks and gas containers. By eating the box o' rocks, Taz can spit out rocks at his enemies. By eating the gas container, Taz can breathe out fire. Each gives ten shots. Extra lives and continues are scattered around in the levels. Also, there are various power-downs as well that take one hit point away. The most common of which are small black bombs. Others include a time bomb, and a cake with dynamite. When eaten, the object explodes making Taz lose one hit point and become black momentarily.

Other objects include shrink and grow potions. While enlarged, Taz can destroy any enemy by simply touching it and enemy attacks do not damage Taz. While shrunk, Taz cannot destroy anything, but can get through narrow passageways. By contacting these items in a spin, they are destroyed, useful on the explosives, but bad on the healing items.>>

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 3:40 pm
by Beyond
Why that little devil, he has his own game :!: :lol:

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 3:49 pm
by Dust Jacket
geckzilla wrote:
jerrythebiker wrote:Air - A colorless, odorless, tasteless, gaseous mixture, mainly nitrogen (approximately 78 percent) and oxygen (approximately 21 percent) with lesser amounts of argon, carbon dioxide, hydrogen, neon, helium, and other gases.


Nope, no "air" on Mars since it has an atmosphere composed of roughly 95% carbon dioxide. I wonder what the locals call it? :shock:
Both online dictionaries I checked included "a light breeze" as a definition for air, which suits the purpose of the APOD description. In any case, dictionaries are obviously written by overly geocentric persons. ;)
Geckzilla, you're just puttin' on airs.

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 4:29 pm
by rigelan
Water is a very dense fluid - and even at slow speeds can cause a lot of damage.
Air on Earth is less dense than water - it takes quite a bit of speed, upwards of 100mph to create significant damage.
I wonder how fast the wind speeds would have to be on Mars to create anything significant enough to damage buildings or structures (If such structures were built on Mars)

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 4:45 pm
by JohnD
For all that dust raised up, there's no mark on the surface to show that it has passed.
The dark line is the shadow.

Why no track?
John

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 4:50 pm
by rb53
Hate to interrupt the fun and games (but I will anyway), I have a more down to "earth" question. Why is the dust devil white? Isn't the dust on Mars red? Could it be low pressure condensation of the carbon dioxide? A cloud? Just asking.[*]

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 5:17 pm
by Chris Peterson
rigelan wrote:Water is a very dense fluid - and even at slow speeds can cause a lot of damage.
Air on Earth is less dense than water - it takes quite a bit of speed, upwards of 100mph to create significant damage.
I wonder how fast the wind speeds would have to be on Mars to create anything significant enough to damage buildings or structures (If such structures were built on Mars)
The kinetic energy of wind (across some aperture) scales linearly with air density, and as the cube of air speed. The surface atmospheric density on Mars is about 1% of that at sea level on Earth. So a 464 mph wind on Mars will have about the same destructive power as a 100 mph wind on Earth. There are low, cold places on Mars with at least twice the nominal density, so there are probably wind conditions severe enough that we'd have to take them into consideration in building structures on Mars.

Sand blasting

Posted: Fri Apr 13, 2012 6:03 pm
by neufer
Chris Peterson wrote:
The kinetic energy of wind (across some aperture) scales linearly with air density, and as the cube of air speed. The surface atmospheric density on Mars is about 1% of that at sea level on Earth. So a 464 mph wind on Mars will have about the same destructive power as a 100 mph wind on Earth. There are low, cold places on Mars with at least twice the nominal density, so there are probably wind conditions severe enough that we'd have to take them into consideration in building structures on Mars.
http://www.marsroverblog.com/discuss-29633-what-are-the-fastest-wind-speeds-observed-on-mars.html wrote:
Andy G wrote:
<<"The maximum wind speed measured by Viking 1. shortly after the onset of the second storm was 31 m/s (~70 mph)."

Given that: Wind energy [i.e., power] = 0.5 * density * v3

A 31m/s wind on Mars (density = 0.02 kg/m3) generates almost 300 Watts per square metre. This is equivalent to 7.9 m/s (18 mph) winds on Earth (density 1.225 kg/m3) where sand would be blown about. Due to the reduced gravity [and dryness] on Mars, it'll be even easier to move sand particles in the Martian environment.>>
LaVache wrote:
<<I make it 0.012 kg/m3 for Martian Atmosphere, Andy, although you may be making allowances for entrained solids. The dynamic viscosity is probably a more significant variable on Mars. Entrained solids on Earth are relatively insignificant due to the increased atmospheric density on Earth, however on Mars, they become a significant factor.>>

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Fri Apr 13, 2012 9:23 pm
by Moonlady
This picture shows clearly that martians have technical problems and use smoke signs for help! :lol:

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Sat Apr 14, 2012 1:22 am
by Flase
Here's a real live dust devil, a tasmanian one. Not everybody knows that they really exist or even that there is a real place called Tasmania (a state of Australia). They are threatened by a contagious facial tumour disease
Image

Re: APOD: A Dust Devil of Mars (2012 Apr 13)

Posted: Wed Apr 18, 2012 1:26 pm
by Irishman
Chris Peterson wrote:
Alnilam wrote:But it's air- substantial enough to produce meteors, ...
Air produces meteors? Oh, you mean that meteors entering Mars' atmosphere actually glow and have tails.