Mars Pictures: NASA's Most Extraordinary Images EVER (PHOTOS), page 2

reply to post by Phage

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Yup that makes sense. If you look at the picture you provided, at the top center of the photo you can see downward flowing "trees". They are coming down off what looks like a peak of the dune or hill.

Awesome pics nonetheless.


I want more. Keep em coming NASA.

Originally posted by Phage
reply to post by beebs

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The dark streaks are slides of dark material on top of light material.

There is a vast region of sand dunes at high northern latitudes on Mars. In the winter, a layer of carbon dioxide ice covers the dunes, and in the spring as the sun warms the ice it evaporates. This is a very active process, and sand dislodged from the crests of the dunes cascades down, forming dark streaks.

[edit on 3/24/2010 by Phage]

Thanks Phage. I still have questions though...

So this carbon dioxide ice is dark colored? Or is just the 'carbon'?

When they say 'melt' what does that mean for carbon dioxide ice? Is the grey colored patches the 'ice'?

Also, I am curious as to the range/mileage/topography of the area - its really hard to tell from the pics. I assume they are saying the black streaks are like carbon avalanches on top of sand.

Why does the melted 'carbon dioxide ice' not seep into the sand? Or when it melts, maybe the water seeping into the sand, leaving a black avalanche residue of carbon?

Maybe water is not involved at all...

Is this relevant at all?:

In its solid state, carbon dioxide is commonly called dry ice.

wiki - CO2

reply to post by beebs

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The dark material is sand but it is important to note (once again) that this is not a "true color" image. It is a false color image which "stretches" the color differences so that features like this can be more easily observed.

They don't say "melt", they say "evaporate". When frozen CO2 warms up it turns directly into CO2 gas. The process is called sublimation.

To experiment with this, next time you have a piece of dry ice to play with try this: put a quarter on top of it and you'll see the quarter start vibrating, it might even start jumping around a bit as the CO2 gas under it builds up. Put a little pressure on the quarter with your finger and it will start to hum...really.

So what is happening on Mars is that a layer of frozen CO2 is warmed by sunlight. The gas inside and under the layer is trapped and wants to get out. The escaping CO2 has enough pressure to move stuff around quite a bit and in the process gets the sand under it sliding down the slope. If you were standing there (oh, I wish!), I bet you'd hear some really strange sounds.

Some people don't like these "mundane" explanations but I find them fascinating. Mars is a very strange place. Strange enough without having to invent trees out of its amazing geological processes.

[edit on 3/24/2010 by Phage]

reply to post by Phage

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Ah thanks that makes much more sense now.

I did not notice that I had substituted 'melt' for 'evaporate', thanks for clarifying that.

I agree, tree or no tree, Mars is absolutely fascinating.

These pictures are so intriguing, I can't imagine anymore my previous notion of mars being a desert wasteland. I mean it might be a desert wasteland in some parts, but a damn interesting desert wasteland.

Any idea about those pockets of dark splotches? Are they just 'dents' in the surface that the wind skips over, with a build up of darker sand?

Also, thanks for reiterating that they are false color images, which I'm sure adds a good measure of awe to them.

reply to post by h1satsu

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Photos from HiRISE have been published weekly (with only some six or seven omissions) since December 2006, and some parts are really orange.

Edited to change "weakly" to "weekly".

[edit on 24/3/2010 by ArMaP]

reply to post by beebs

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I know what you mean. When the first images from Viking showed up I was disappointed.

But now, with what we've gotten from the rovers and what we're getting from the orbiters it clear that Mars really is a whole world full of a huge range of amazing things. It's amazing how similar some of those things are to what we find on Earth and even more amazing in the differences.

I think the dark splotches are an example of another weird martian phenomenon, a variation on the theme: CO2 geysers

reply to post by Agent_USA_Supporter

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If those things are trees, where are their shadows?

We can see the shadows of the dunes and not the shadows of the "trees", don't you find that a little strange?

apod.nasa.gov...

maybe it could be this ? sorry if its been posted i havent opened all links

reply to post by solarstorm

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Well you simply seriously misunderstand what you are looking at. I know this is some kind of 'conspiracy site', but try to focus on real conspiracies, because there is not one here, or there, so to speak.

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