[X] My Assistant

[Guest_Steve39_*]

Hello My name is Steve and I had some questions about this image in relation to the current model of current conditions on Mars.

I am new and I understand that some of the greatest minds reside here. I would like to start a discussion on this visible data if possible.

To summarize my position of the image, voids created by CO2 sublimation from beneath. The compression and associated gas release produced the movement of surface features visible. This seems reasonable.

The layering and current surface ice at the polar cap in spite of seasonal dust deposition, post CO2 sublimation, without another source of H2O seems unreasonable.

I would be grateful for any help to reconcile this

Thanks in advance,
Steve

Image from Hortonheardawho

[dvandorn]

Well, Steve -- not that I doubt the presence of frozen volatiles under the footpads at the Phoenix site (obviously!), but I don't see any landform indications of what has been designated "layered polar terrain" at the landing site.

There is no doubt that water and other volatiles are trapped in the ground at the latitude where Phoenix sits, but I don't see any evidence thus far that this latitude sees the ongoing, annual, dynamic deposition of layering that is seen closer to the poles, where the image you posted is from. Layering may well have happened here long ago, at times when the various ices were deposited here more robustly, but for right now, I'm thinking that we're not actually laying down new layers of ice and soil every year at this site.

My take on the cycle seen at this latitude is that a seasonal layer of CO2 ice is laid down every year, which completely sublimates every spring. Whatever thin veneer of water ice that may exist in mid-spring after the CO2 ice goes away simply sublimates away, itself, as summer approaches. It's then carried in the air down to the other pole, where it's laid down in similar transient veneers near the south pole. As seasons change, that water makes a grand traverse from one pole to the other, with the maximum amount of water "in transit," carried in the Martian atmosphere, at equinox.

I just don't see landform indications that annual deposition of new permanent layering is actually happening at the Phoenix site. Further north, yes... but not here.

-the other Doug