NASA Reveals Dust Devil Data from Mars 116
saskboy writes "NASA reports that Martian dust devils could be much more destructive than previously considered. You may remember this past April when it was revealed that whirlwinds actually helped the current rovers by cleaning accumulated dust from their solar cells which increased their energy collection efficiency.
But after studying the mini-storms more, they realize that the dust and sand particles could cause static electricity discharges, also known as lightning. The high speed grains of sand blowing around at about 30 meters/second (70 miles per hour) are nothing to blink at either, since they can damage astronauts or equipment on the Martian surface. The height of a Martian dust devil can reach 10km (6 miles), which means it's more like the size of a terran tornado."
At 1/100th earth pressure? (Score:4, Informative)
I walked into a dust devil here on earth... (Score:2, Informative)
My friend and I were on a road trip, and I asked him to pull over.
I ran into this thing, and it was really weird - the air around it was still, but the dust devil itself was really windy inside!
It took only a second or two to walk in and out of it, but it was an interesting experience.
Not as powerful as tornadoes... (Score:5, Informative)
But no where near the destructive force of a tornado, which may be why they're calling them dust devils...
It's less than 1/3 the windspeed and since the atmosphere is less dense the total energy will not be anywhere close...
Grounding to help with static electricity? (Score:5, Informative)
"Sand" (Score:4, Informative)
Just to be clear, we're not talking about "sand" in the sense that your average beachgoer thinks of it. The typical size of the dust grains on Mars is a few tens of microns (say 10-30m or so), which is quite a bit smaller than sand, which ranges from a few hundredths of a millimeter to a couple millimeters in size (roughly, using geological definitions).
Re:"Sand" (Score:1, Informative)
The typical size of the dust grains on Mars is a few tens of microns
ten microns = 10um
than sand, which ranges from a few hundredths of a millimeter
hundreths of a millimeter = 10um
So you are saying that they have the same size, aren't you?
(Gratulations to the mods who modded this up. You failed it.)
Re:A quick question (Score:3, Informative)
Both tornados and dust devils happen when the air close to the ground is warmer than the air up a bit higher. In tornados, there is a lot more power generated over a larger area (and has the potential to do more damage) than a dust devil would.
Because of the thin martian air, the dust devils have little destructive power so they aren't called tornados.
Re:"Sand" (Score:1, Informative)
Your original post was stupid and gave a wrong impression: you were talking about tens of microns and hundredths of a milimeter, which is the same but gives to the casual reader the impression that the one is bigger than the other. Learn to express yourself clearly. Or do you want to go into politics?
Better whirlwind videos (Score:4, Informative)
http://photojournal.jpl.nasa.gov/catalog/PIA07139 [nasa.gov]
http://photojournal.jpl.nasa.gov/catalog/PIA07140 [nasa.gov]
http://photojournal.jpl.nasa.gov/catalog/PIA07138 [nasa.gov]
There's also a rather neat video of Opportunity escaping from the sand trap [nasa.gov].