Goodbye Purgatory Dune!, Oppy on the move Options

[Tesheiner]

On the road again...

http://nasa.exploratorium.edu/mars/opportu...WEP1211L0M1.JPG

[sapodilla]

I really hope so. Maybe we see Victoria before Christmas.

[djellison]

Goodbye Purgatory..we barely knew ye...

well, actually, we've gotten to know ye quite well

Doug

[dvandorn]

We got to know ye better than I ever wanted to!



-the other Doug

[Reckless]

It's good to be moving again. As I'm mostly an onlooker I look forward to seeing who will be first to show the point on the route where Oppy will stop driving north and turn back toward the south. Will it be east or west first my guess north then west then south.
Thanks to all the forum contributions.
Reckless

[ilbasso]

I'll have to admit that I was skeptical that there was anything different about the makeup of Purgatory Dune when Oppy first got stuck there. In the image Tesheiner posted above, I'm amazed to see that Oppy dug in quite far into the dune surface even when it was positioning itself for its investigations over the past week. That is a MIGHTY soft dune!

[RNeuhaus]

I feel it is a sensate decision not to adventure going toward south unless its traction capability is improved as the required for that zone without any other help and also as remote robot. I know it is very brave to transverse thru chopped dunes. Hope that the team will get greater information about the land and trace the safest and easiet route toward to Erberus or Victoria????

Rodolfo

[jvandriel]

Panorame wheeltracks in front of Opportunity at Purgatory Dune.

jvandriel

Attached thumbnail(s)

 

[jvandriel]

Panorama wheeltracks at the rear of Opportunity at Purgatory Dune.
Taken with the L Navcam on Sol 510.

jvandriel

Attached thumbnail(s)

 

[pioneer]

On the road again...

http://nasa.exploratorium.edu/mars/opportu...WEP1211L0M1.JPG

Glad to know we're back

[Bill Harris]

Panorama wheeltracks at the rear of Opportunity at Purgatory Dune.

And we're already starting to get downwind tails from the recent wheeltracks. These are potentially active dunes!

--Bill

[Marcel]

And we're already starting to get downwind tails from the recent wheeltracks.  These are potentially active dunes!

--Bill

Only if the "pavement" is broken I'd say. Then the fines underneath are exposed and free to go. My feeling says that the winds on Mars don't carry enough energy to break apart the upper layer. I wonder for how long this situation has been that way. And (even more intersting to know): What process is responsible for this tough upper layer ? Liberation of chemically bond water by intense and long UV-exposure, on it's turn cementing together the minerals ?

[RNeuhaus]

I put my comments, I have seen a fine sand cementing cap on the desert. This cementing strate is very fragil. Once it is pressed, it cracks very easy. This case was caused by evaporating wet sand. This is only valid for a short time that is not the case for Mars that the water might probably have gone completely after 1.2 Billones years since its conception.

Rodolfo

[Guest_BruceMoomaw_*]

Actually, we've seen a surface crust on Mars' soil virtually everywhere we've landed -- the Vikings saw it clearly. It seems be a salt crust left behind by very small traces of surface liquid water left behind in the upper surface soil seasonally (along with some more dramatic moistening at intervals of a few tens of thousands of years as Mars' axial tilt changes and water ice thus migrates back and forth between the planet's polar and equatorial regions). It certainly doesn't ever require the existence of large amounts of liquid water on the surface at any time.

[Bill Harris]

That is why I sail "potentially" active dunes. With the desert pavment/duricrust/"cementicrust" on the dunes it may take milennia for them to move. But we see here that the atmosphere can and does have the ability to move fine surface dust on a daily and routine basis. Oppy is not in the midst of a windstorm and the dust from the wheeltrack disturbance is rapidly moving in s short time.

In another thought, even though the density of the Martian atmosphere is very low and cannot move heavier particles like blueberries, it might happen that during dust storms and high wind velocity events, the wind can pick up sediment as a bedload and the density of the wind+bedload might be high enough to move heavier particles and thereby move dunes.

There is a lot to learn here.

--Bill