Whirlwinds on Mars, From the Ground

Neil Halelamien writes "Back in 1999, satellite images were photographed of 5-mile-high whirlwinds streaking across the surface of Mars. A couple of months ago the Spirit rover got a close up view of whirlwind tracks, and this past week photographed a whirlwind in action (animation). It's thought that these dust devils may be responsible for the mystery power boost to the rovers' solar cells. Last year the rovers also spotted clouds and frost."

Comments

Animation

[FTL]

Incase you are wondering about the /.ed animation, it is a two-frame, black and white, 1MB gif. The first frame shows a small whirlwind in the distance, the second frame doesn't show the whirlwind.

Not impressive compared to the tornado footage we're used to from the local TV station. But one must remember that the rovers' actions are scripted in advance. So it was a complete coincidence that a whirlwind happened to be in-frame when they took a photo. Which says something about how common they must be if we just happened to snag a picture of one.

If you are still interested, here's a mirror.

Re:Animation

[Zone-MR]

it won't tell us anything about how common they are until they snag a picture of another one

Yeah it does. We can assume that a tornado is visible 1/Nth of the time, where N is the total number of pictures taken by the rover, and the 1 represents the picture with the tornado visible.

If the rover snags a picture of another tornado it will increase the accuracy of our prediction slightly.

Re:Animation

[drinkypoo]

That is way way way too simple. You have to take into consideration the field of view, the amount of movement, the frequency of the pictures, the speed of the phenomenon, and the relatively short time in Mars' period that we have had rovers there :P For all we know there's ten times as many (or ten times fewer) tornadoes in other parts of Mars, due to terrain features...

Re:Animation

[QuantumFTL]

Calling it an "animation" is stretching it pretty far. The second frame isn't even on-register with the first one, so it's really just a pair of "with" and "without" snapshots.

I used to work on MER, and I discussed this issue with Daniel Crotty (the man who made the animation featured here), and it was decided that:

1. Good coregistration was too difficult with the available information. I've written coregistration code before, for the CAHV linearized images, however there are serious problems when using the CAHVOR or CAHVORE model images (Navcam is CAHVOR). This is because not only is the distortion in the model nonlinear, but it depends on the distance of the point from the camera - something that we can only approximate using a planar surface model. My suggestion for coregistration, given the current information, would be to do feature matching to generate a set of "equivilent" points in each image plane, and create a function which, given a relative position and orientation, would generate rays from each matching point. A nonlinear optimization algorithm (perhaps simplex method solver) would then iterate until it found a relative position/orientation that minimized the mean square distance between "equivilent" rays. I believe this is similar to how much motion tracking software works. This is, however, quite difficult to do without a preprogrammed software package designed to do this. After this the second image would still have to be projected on to the planar model of Mars, which is also nontrivial.
2. From a purely scientific point of view, "proper" coregistration is almost entirely unnecessary. Because of the fact that the phenomenon is so far away, the far field effect takes care of almost all of the error. There is a two dimensional coregistration method that could be used for this purpose (Alex Hayes, Cornell '03, described it in his honors thesis) using multiple fourier transforms, one in linear space (for shifts), and one in radial/logarithmic space (for rotations and scaling).

Anyways I think the current image serves the public just fine. The file is so large because it was created in GIMP, which does not seem to support LZW compression of GIF images for a legal (?) reason. (I thought the patent expired...)

As for it not being an animation... how many frames do you need for something to be an animation?

Cheers,
Justin Wick

Re:Windsock

[FrostedWheat]

Pathfinder had something I liked to call the wind chimes. They didn't move about much, I'm guessing because that lander was so close to the ground and the landscape was quite rocky.

Here's an animation here and some info.

Troll alert - mod down!

[Anonymous Coward]

"Hidden" movie spoilers from ROTS in the text.

frost already observed in 1979 by Viking

[idlake]

Frost on Mars had already been observed by Viking in 1979 (e.g., here).

Re:For the hardcore:

[iamlucky13]

I don't know how much credence the idea has right now, but the original guess I heard from JPL was it was water vapor was causing the dust to clump as it condensed, froze and expanded, then melted and evaporated or else sublimated. Of course, they took pictures of the solar panels on Opportunity and didn't see any clumps, so if they existed, the clumped dust must have been more susceptible to being blown off in a gentle breeze. They have, however, taken several pictures of frost on the rovers.

Re:Would these be good areas for missions?

[iamlucky13]

It doesn't seem like a good thing to count on. In Spirit's case, it was over 400 days into the mission before it got this boost. They've been dealing with decreased energy availability for months. Plus, they estimated the odds were about equally as likely that some other critical part of the rover would fail before the solar panels became obscured. They will, however, probably reconsider their estimates for how long a solar powered rover can operate. The Sojourner lasted about 90 days, so they figured with the increased panel area, they could probably double that.

The next rover mission (Mars Surface Laboratory) will probably be nuclear powered so they can guarantee energy degradation won't be a problem unless it survives for quite a few years. This would also mean they aren't limited to locations near the equator, so if NASA decides there's something interesting near the poles, they can go there. Since the landing method will be different, the rover will be able to land in an area about 1/5 the size of the current rovers. This should give the mission planners a lot more options than they had with the twin Spirit and Opportunity, which landed on a big empty plain and on the floor of a giant, ancient crater respectively.

Here ya go

[zogger]

composition

95.3% carbon dioxide (CO2),

2.7% nitrogen (N2),

1.6% argon (Ar),

0.15% oxygen (O2),

0.03% water vapor (H2O)

pressure

1-9 millibars, depending on altitude; average 7 mb

A little shy on the O2 department without a lot of terraforming action, pressure pretty low too, in short, no walking around without a spacesuit of some kind. It would seem possible though, given a large enough power source, you could run oxygen accumulators for inside use in your structures, etc..

taken from http://www.daviddarling.info/encyclopedia/M/Marsat mos.html

Not unlike early earth

[Anonymous Coward]

Thats not too unlike early Earth's atmosphere.

...While oxygen currently makes up 21 percent of the atmosphere, there was only a trace in the air when life first appeared on the planet. The single-celled bacterium dwelling in the oceans did not need oxygen to live....

From the Geology department of the University of Florida:
http://ess.geology.ufl.edu/HTMLpages/ESS /GLY1033_n otes/lecture1.html

Compared to Earth's Atmosphere

[AtomicSnarl]

The standard atmosphere surface pressure on earth is 1013.23 millibars (mb), or 29.92 inches of mercury.

A record High Pressure in Siberia made it up to 1083.8 mb/32.01 inches, and a Pacific Typhoon had a record low pressure of 879 mb/25.69 inches of mercury.

So, compared to Earth by altitude (approximately):
5,000 feet - 850 mb, 1 mile high 10,000 ft - 700 mb, 2 miles Oxygen required for unpressurized aircraft 18,000 ft - 500 mb (half the atmosphere is above/below this level), 3 miles 30,000 ft - 300 mb (70% of atmosphere is below), 6 miles high, entering the Stratosphere Dead Zone: Fatal without 100% oxygen source 53,000 ft - 100 mb (90% below, 10 miles, Stratosphere Fatal without Pressure suit: Blood pressure exceedes environment pressure, so oxygen is not absorbed Blood starts to outgas (boil) causing the Bends 68,000 ft - 50 mb (95%) 13 miles 102,000 ft - 10 mb (99%) 20 miles 104,000 ft - 9 mb High pressure on Mars 110,000 ft - 7 mb Average Mars pressure, 24 miles aloft on Earth 120,000 ft - 5 mb (99.5%) Higher terrain Mars pressure 157,000 ft - 1 mb (99.9%) Mars mountain tops, 30 miles on Earth Oh, yes - Earth has 78% Nitrogen, 21% Oxygen, 1% Argon, Carbon Dioxide, and all that. Water vapor can be up to 4% or so on hot, humid days.

In other words, Mars Tourists will need to pack much more than a towel and sunscreen.