A weird looking surface feature.........

No closeups of it form pancam yet though. They seem to have pointed the camera at everything EXCEPT this feature.

An interesting feature - but probably very similar to the outcrop inside Eagle

The cool thing is that opportunity has driven from one target seen on orbit - to another - like Spirit has.



the drive to Endurance doesnt seem that far when you can pull 150 metres in 48 hours.

Doug

Is this the crevice that Opp. saw a few days ago. Or, is this the second target Opp has seen since leaving bounce?

It's the same crevice. It arrived after a 100m drive, and has driven about 50 metres along the side of it.

Doug

Looking back partway through the 100-m drive, here's a pretty cool navcam shot showing Bounce as well as the parachute & shell in the distance:



Also, the drive along the trench:

I've ressurected an old thread to post a newly-made polar projection... this is Anatolia, close to Eagle crater. Two partial pans from the MER Notebook Navigator site joined to make one. I am going to work on a detailed map of Anatolia as an experiment for future mapping.

Phil

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So long ago and so far away.

Those are truly monster ripples (ripplets? ) that Oppy is crashing over....

Interesting polar pan... Eagle/Bounce to the SW, Endurance on the Eastern horizon. I've been doing a "round-tuit" side project of looking at MOC imagery of the Meridiani area and plotting/marking the anatolia lineations. Somewhat of an academic project, once one plots a few of these things and see that they trend NE/SW one begins to wonder about the focus of the project. But as a geologist I notice lineations as telling a lot about subsurface conditions. In my Appalachian mountain setting, lineations imply tectonic forces but on a desert plain like Meridiani I think that they reflect the surface of the evaporite unit and may offer clues about the depositional environment here.

Another mapping puzzle to work on? Look at the wind direction in this region of Meridiani as suggested by the dust tails behind craters. Unless I've got North mixed up, the wind direction seems to change from place to place.

--Bill

Here is a polar version of the sol 72 pan at the north end of Anatolia.

Phil

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And here's the Sol 71 half-pan in polar form.

I don't have directions all set up properly here. But I want to use these (or larger versions of them) and the vertical projections from the Planetary Image Atlas to assemble a map of the area. This is an experiment at producing a background image for day-to-day route mapping, similar to what Dilo is doing now.

Phil

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They do change direction. There are orbital images showing the tails on opposite sides of craters.

Nice projections Phil...

Nico

Although I've lost the reference, I read recently that the wind direction at Meridiani changes seasonally, sometimes coming from the NW and then from the SE.

Here's a polar half-pan made earlier on Sol 72 than the full pan above.

Phil

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... and a pan from Sol 74, omitting the foreground to emphasize distant features. The fracture patterns north of Anatolia show up here. I'll do the full 74 pan soon. Then the goal is to try to knit them all together into a regional map.

Phil

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Man I love that sol 72 projection

Can you show a bigger version?

Nico

OK, I'll try to get it out tonight my time.

Phil

Great work, Phil! It'll look awesome once you get everything stiched together, not to mention how informative it will be.

Great views of Anatolia, thanks Phil !
These projections enhance the feeling of being there, and observing the martian scenery from up close. Which invites this (out of subject thread) question :
Since images and distances of features from the rovers' current location are (or will be) known, how difficult is it to construct a VR world that includes Meridiani and Gusev ?
Some aerial views of Columbia Hils published by JPL a short while ago approximate what I have in mind, but a VR world would be way better (although the scientific merit might admittedly be questionable)

How cool would it be to float 2m above Endurance, looking at Burns Cliff and the sand dunes !

well, we've got the pics, and a reasonable terrain model could be put togther from them - Ron Li has already done some of this - so somebody with lots of time and suitable software could certainly do it.

Phil

Nico asked for a larger sol 72 pan. I hope this is the one (of two on that day) which was intended.

Phil

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I was wondering what causes the pairs of "objects" that appear on a radial extending at about an angle of 70 degrees from the center to the horizon. I suspect it is some kind of spurious projection generated in the image processing. But I would like to hear exactly what causes it (before some other forum identifies this as the latest example of proof of civilization on the 4th rock from the sun).

Those areas are along a stitch line and appear to be a transmission loss in one of the frames that was Autostitched.

--Bill

After comparing the ripples around Antolia and Erebus, there is a big difference.

I have the impression that the way between Eagle and Endurace, looks like a calm sea and around Erebus looks like that there were more current of water if that zone was a lake.

The more current is the water (due to greater slope pending) around Erebus than around Endurance, the surface has bigger waves of ripples around the Erebus.

Rodolfo

I think the ripples are eolian features, so water depth is of no significance regarding their size.

The dark spots mentioned by DFinfrock are from the original panorama mosaic at the PDS site. I very rarely find time to make my own pans. If you look closely you will see several others closer to the centre but getting smaller near the centre. The spots are actually labels showing elevation angles on the mosaic. I could have edited them out but didn't.


PS slight delay on the Anatolia map. I got sidetracked by a new map of Eagle crater which I will release soon.
Phil

Thank you for the big one Phil

Nico

Well, duh. So they are.

We are seeing "anatolia-like" features on the Olympia-Mogollon boundary at Erebus. The "sand" (ripple material) is evidently moving into fractures or voids in the bedrock which which may be the cause of these anatolia features and of the small craters we've been seeing. I think of the term "sapping" when I think of this sand withdrawl, but that is a loaded term since it implies groundwater so we should use another descriptive term.

I can visualize this "sand withdrawl" process easily enough, it occurs in the Karst topography that I'm familiar with. The problem I have is "where does the sand go?" once it goes into the void or fracture. Once a fracture fills up, no more sand can enter and that is all it will ever do. There must be a process that removes the sand, like flowing water in a cavern, or very deep fractures or active fractures that are young and keep opening. All of which, IMO, are not likely to to be happening here.

Any ideas of a process that could be involved here (besides "pugilistic microbes" eating the sand... )?

--Bill

That topic is interesting. If these holes have stopped of sapping process, then after hundreds, thousands or millions years, depending to the eolian force, these holes whould be totally concealed.

Then these sapping must be somewhat related with something under sub-surface is changing its state. Maybe it is due to a sublimation process of remant water under the sub-sufarce.

Also, maybe, another kind of material, amoniaca, the decomposition of something that might reduce its size and that process may lead to sink the upper portion of sand.

Rodolfo

That zone, from Eagle to Erebus crater is relatively plane with slight positive from North to South. The wind force must be about the same for all that zone except to around Erebus rim where there might be somewhat more due to higher surface.

On the other hand, I have observed that the zone with stronger wind, the surface has bigger ripples than other zone with tenue winds.

The conclusion, the beginning, the water have played the formation of waves of the surface and later by the eolian factor.

Rodolfo

If the subsurface is a large portion of brine ice, it shoudl continue to outgas and shrink, especially during Mars' processional cycles which would be the basis of greatest change. Such outgassing and surface contraction and cracking followed by filling could go on far into the future, or whenever Mars' runs out of gas...

are we still inside that window? i dont know but i think this window of time might be far longer than we expect of an otherwise geologically comatose planet.

It seems logical to me to suspect that the processes forming the the large features at Anatolia are the same or similar to those causing the smaller features we're seeing at Erebus (and that we've also seen at Endurance and elsewhere). Some kind of subsurface sapping or subsidence activity is the only way that I can think of to form them. But I run into the same problem Bill described. Once the crack fills up, how do you continue to maintain a surface expression as drifting sand/dust continually moves in to fill the low spots?

I'm guessing that the fractures at Erebus are probably billions of years old, while those around Eagle and Endurance are much more recent. But maybe something unrelated to the impacts has created fractures. Regardless, I have to suspect something more recent is creating these features in the drifts. If it is sublimating subsurface ice creating the voids, it would be amazing after all these years. I was imagining all the shallow ice this near to the equator would be gone by now. These features really are other-worldly. I have not been able to come up with a set of processes to form them that is satisfactory to me. Could periodic temperature changes cause expansion and contraction that compresses the sediment to create new space? Maybe the processes of sediment compaction at Meridiani are slower than one would expect on earth...

The only other factor I can think of that could cause geologically recent surface cracking would be isostatic rebound. I know that Mars' axis precesses badly, sometimes pointing 60 or more degrees out of perpendicular to the ecliptic -- maybe crustal deformation caused by extensive solid CO2 deposition as close as 15 or 20 degrees, either north or south (or both) from Meridiani, could have caused the soft, weak beds of evaporite to crack.

The axis precesses over fairly short periods of time, geologically speaking... maybe these cracks are an as-yet-unrecognized result of CO2 "glaciation" encroaching somewhat close to the equator?

I wouldn't think you'd get direct solid CO2 build-up on the equatorial regions themselves... otherwise, I'd suggest the possibility that direct dry ice build-up could have depressed the local surface and caused the visible cracking.

-the other Doug

I used to think that the Anatolian cracks and divots were formed by the aeolian loss of evaporite bedrock itself, winds perturbed by local surface features building up turbulence and exagerating features by sandblasting and blowing away exposed areas of the powdery evaporite and leaving voids to be filled in with the bigger sand grains and blueberrries that fall out of it, sort of a dry-man's ice-sapping phenomenon. this just seems too far-fetched now.

On a wetter note, i think there was enough of a water ice table below the surface to form these small cracks in this very slow manner by evaporation driven contraction. When these sediments were laid down, the water saturated salts in them would tend to hang on for a very long time, but inevitably the plains slowly dessicated and contracted into crackworks, most of the major faults having already formed by impact shocks.

i would dread to assume that the reason we still see the cracks is because they are merely still filling up, that would imply that there isnt much sand movement at all in the scheme of things, though loose the sands be, they are relic dunes.. no, these dunes sure look mobile, on the order of a few decades-per-meter (?), but they havent sailed on to cover over the plains near Endurance, as those are almost flat, and the sand is apparently not blowing into the locale of Endurance, but it seems to be collecting in this area, or its slowly emptying out of this area and maybe the source of the sand here was local from Victoria's apron mess.. perhaps ive missed something rudimentary here about aeolian science, but why would there be much dune height variation between these areas anyway? does there seem any geographical reason the wind speeds might differ enough to set up these disparate situations?

One part of the answer to the ground heaving signs in some of the Meridiani areas is the chemical nature of the sulfate rock: It contains abundant water of hydration, and can gain and lose that water with time, changing between different hydrated minerals, for example, Gypsum and Anhydrite, on Earth. Both calcium sulfate, but one's hydrated and the other isn't.

Remember the big rock in Endurance... biggest one in a cluster of boulders low down in the crater where Oppy passed on the way to Burn's cliff. It looked like a giant thanksgiving turkey, with a fractured crazed crust dotted with blueberries. Squyres and co. think that pattern results from weathering exposing fresh rock to the atmosphere or where atmosphere can diffuse in or out, including water vapor.... and the rock surface swells and contracts with hydration phase changes during relatively minor climate shifts, causing the cracking pattern.

Similar activity could cause some heaving and settling of the general sulfate rock "pavement" elswhere. Maybe.

Attached is the anatolia lineation map that I've worked up in the Eagle-Endurance region. Take some of these markings with a grain of salt; I may have gotten bit by the Schiaparelli-canali bug. My criteria was assuming that the light was from the northwest and for a depression, the shadow side is the NW side. The blue line represents where the ripples start to increase south of Endurance.

Good thought, edstrick. There is some force driving the 'tectonic' engine here and it may be something as simple and subtle as hydration.


--Bill

Here's my promised Anatolia map. I have reduced the original resolution and JPG quality for posting. The mapped area is 100 m by 50 m.

Phil

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We have had some images of Endurance from Erebus. Here I look in the other direction. This is a pan - the horizon area only - from Anatolia. The relief is greatly exaggerated, at least tenfold but I forgot to record how much... duh! The original pan from PDS had some distortions - I don't think the horizon near Endurance really looks like that.

I have labelled things to make it easier to interpret. Note especially how Erebus shows up clearly as a dark rise. Once we are beyond it there will be a new landscape to see. I labelled a more distant ridge as possibly Victoria crater... but I haven't checked the azimuth to see if that's true. It might just be part of the etched terrain. Maybe someone can help out?

Phil

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What sol is this pan from Phil?

The Anatolia map looks great.

Nico

The horizon view was from Sol 72.

Phil

Here is an Anatolia project that I've been working on: this is a delineation of the "anatolia lineations" around Eagle-Endurance crater, from the MER_DIMES image. The lineations are highlighted in red and the informal boundary between the smoother non-rippled terrain around trhe landing site and the more rippled terrain to the South is shown as a blue-green line.

Lighting is from the Northwest and I've tried to not highlight albedo features.

Make of it what you will. The only conclusion I've reached is that we're no longer in Kansas, Toto.

--Bill



EDIT: removed redundant image:

http://www.unmannedspaceflight.com/index.p...pe=post&id=2511

Bill:

I think you've just demonstrated the need for some really good MRO coverage of this area!

Bob Shaw

Oh yes, high-resolution aerials will be a plus for a survey like this. I need to work up a comparison image set using Phil's MER polar view and the same area of this image (with the "highlight" layer turned off or way dimmer).

But still, you can spot definite trends in the lineations and a fabric to the patterns. Although I'm lukewarm to a strict Karst interpretation, the pattern does seem like the axes of a stress/strain ellipsoid which would define a joint/fracture system.

We'll get a lot of mileage from the MRO coverage of this 'ground truth' and vice versa for years to come.

--Bill


PS-- dang, sorry, folks for the deja vu-vu. I'd forgotten that I posted this same image 6 months ago. I'll let it stand, and use this faux-pas as a subtle _bump_ of the thread. "CRS" sets in.