Well, with Oppy on solid ground now I think we can say she has officially arrived at the Etched terrain.

On a side note, is it my imagination, or is the dust in the air clearing a lot the past few days? I haven't seen a shot this clear in ages...or perhaps this etched terrain is on slightly higher ground than the surround sea of dunes?

http://marsrovers.jpl.nasa.gov/gallery/all...47P0607L0M1.JPG

Oppy should be able to traverse more quickly over this rocky ground. Is Victoria peeking up from the horizon ?

> Oppy should be able to traverse more quickly over this rocky ground.

Yes, but see that there are more sandy terrain until we reach Erebus.

> Is Victoria peeking up from the horizon ?

As already said before, Victoria is below the current line of sight.
It won't be visible until a point more or less at the half-way between Erebus and Victoria.

I see that around there, etched terrain, there are more outcrop than the north way from the Endurance crater. The question is why it is so?

1) The land is higher than the north?

2) This zone has stronger or more often winds?

3) The water started to flow first around Erebus?

4) "By that time there were more Roman cart traffic?

Rodolfo.

With my opinion Erebus, like Bonneville, is not a major scientific target, as it is filled with sand and probably dangerous to try to descend in. So it is possible that they even not attempt to get closer, taking a short cut through etched terrain toward Victoria. The later is anyway an important target, at it may exhibits a much thicker layer of evaporites than Endurance. So the situation is similar to Endurance, but there may be no way to descend into Victoria, or no way to get out.
At last we are now sure that etched terrain is exposed layers of evaporites.
But with RNeuhaus I wonder why terrains are so different, while sharing the same geological properties (20-40cms of sand on evaporites):
-Near Endurance, flat terrain with only small ripples
-Near Viking, larger dunes
-An now round Victoria-Erebus, dunes separated by troughs hollowed down to the evaporite layer.

Would it be wind channels on Mars? And why?
Maybe the ration sand/blueberries is responsible for the dunes variations? or some component of the evaporites?

Erebus is potentially an important target since it is a deep excavation in the Evaporite sequence which has much of the ejecta weathered and eroded away. We are essentially left with a big road cut: although the interior of Erebus is sand-filled, the walls are visible With Victoria, it is newer and fresher and has a huge ejecta blanket obscuring details.

IMO, a significant target here ought to the "dark basal unit" (D1, D2 and those &%$# dark angular pieces we see) since it is something we didn't see at Endurance.

--Bill

Let's see what the science instruments tell us about the etched terrain outcrop.
It seems the weekend will be spent there :

Bill,

Looking at the map there might be some pretty hefty dune fields between Oppy and those targets (D1, D2). Driving through Erebus itself seems totally out of the question, so how likely is it that we can reach these outcrops? On this side of the crater there doesn't seem to be so much interesting stuff, does it? And how much topography does the etched terrain actually offer? Between this location and Victoria it seems to be as flat as a pancake. Maybe this is enough reason to put the pettle to the metal and try to reach Victoria ASAP?

There may be dune fields, but there is also the evaporite pavement along the north side of Erebus, which might be easily travelled. We'll see what it looks like once we get to Erebus.

--Bill

Bill,


the evaporite pavement near Erebus is already known, and there is no hope to go deeper in Erebus than in Endurance, so I think it is why Erebus is not an important science target.
On the other hand, there is this pavement you mention along the norh side of Erebus, that may be easily traversed. (At rough guess, as it seems that there are many "Anatolia type" pits and cracks in the etched terrain). If they choose this path, they could spare some days to have a look into Erebus.
What makes Victoria very interesting, is that it is much deeper than Endurance, and so deeper layers of evaporite may be exposed, eventually underlying layers of another nature (which seem black in comparison with the evaporites). So They will certainly try to descend into Victoria, even if they could never get out of it. A similar bargain was made when discussing about descending into Endurance.

New PanCam images!
This is the full-res stitch from L2+L7 filters:
Click to view attachment

And we have a RAT - the first RAT in many months!!!
http://marsrovers.jpl.nasa.gov/gallery/all...47P2573R1M1.JPG

You wouldn't need to go into Victoria crater to examine the deeper layers. After all Victoria is a crater so you could examine the ejecta to measure the same stuff. Ofcourse this wouldn't give you direct information about the depth the stuff came from, but miniTES might help there. Also I think it wouldn't be a big deal if you could get in, but couldn't get out. I guess that other stuff that's different enough from what we've already seen to make it scientifically worthwhile, is probably way too far away to reach it. So going into Victoria and dying there may be very well the right choice.

Yikes, some of those dunes look pretty darn big.

Loads of exposed rock all over the place here too. Hopefully the wind will have granted us safe passage between the dunes. I too would like to see Victoria. I wonder how many Pancam shots it'd take to get a rim-based panorama of that.

The same number of shots that it would take to get a panorama of anything else.

Wow it looks really deep!

I thought it had some kind of higher res mode. I guess that's that super-res technique that I'm thinking of. Hm.
Stinks that the rovers haven't got zoom lenses. But I suppose that's just one more thing that could fail.

What previously appeared like outcrops on the South and West sides of Erebus are looking more and more like large dunes on the flat "pavement that" Oppy is standing on right now. Certainly deserves a closer look, but not as exciting as I originally thought.

On the move again:

http://marsrovers.jpl.nasa.gov/gallery/all...XP1390R0M1.HTML

Whew. Look at the Sol 549 MI's of the RAT hole done on Sol 546.

This is super-weird.

--Bill

OK Bill I'm looking. Help me out here. I always enjoy a good weirding-out at the end of the day, but I'm not seeing it.

Is this the MI series you are talking about?
http://marsrovers.jpl.nasa.gov/gallery/all...47P2936M2M1.JPG

I wish they would clean out they holes they just finished Rating.

Wouldn't it make sense to see what you just bored out!?

I don't think they CAN clean it out. The stuff is so soft and crumbly its like boring a hole in a cake and then trying to brush the crumbs out of the hole. The wire brush itself is stiff enough to keep dislodging more material from the bottom of the hole! And if the hole is nearly flat horizontal there's nowhere for them to fall after they have been brushed "away".

It's not necessarily all that soft.. if it were consistently that soft, they could just use the brush and ditch the RAT altogether. I suppose it's possible that every rock has a thin hard outer shell covering a largely soft interior, but that seems unlikely to me.

They could at least try to brush one of them. It is odd that they haven't ever tried.

Oo-ee, gooey, rich and chewy inside...
Golden, flaky, tender cakey outside..
Wrap the inside in the outside.........


Sorry, had to.

Now, there's an interesting new perspective on Areology -- that Mars is one giant Fig Newton!

And who knows -- maybe there are chocolate fudge volcanoes on Venus...

-the other Doug

Now it seems she fully reached the highway!...
Sol549

Near this point: Click to view attachment
(Original navcam picture from sol 543)

Edited: And if previous estimations for sol 543 position were accurate, we are about to leave the highway for another 100m of "desert crossing" until standing again on rocky terrain.

Sol 546 image of RAT: clean, with lots of interesting details seen.

Sol 549 image of RAT: cuttings blown into hole.

Unless I'm looking at a second RAT hole.

Data point: it is especially windy at Meridiani.

--Bill

They might have used the RAT again on the same hole to make it deeper.

It does not look deeper though ...
Gee, two sols of images missing (547, 548), and a RAT hole covered in sand.
Do you think we had a major "cleaning event" that was more fierce than the previous ones ?

And if you look closely you can see some of the RATted blueberries faintly through the blown dust, so I think this is the same hole.

Given the dustdevil activity at Gusev, I'd suspect similar aeolian activity at Meridiani. We may see fewer (or no) DDs here because Meridiani is less dusty, being paved in blueberries. Recall the rapid changes on the rover tracks at Purgatory-- within a few days, the underlying dust was streaking away from the disturbed areas.

--Bill


PS-- Oppy did take a series of solar panel MI's, so we may know if there was a cleaning event soon. And we can check the solar panel output as it has been decreasing.

It's the same hole for sure - but wow - lot of dust dumped in there

One would hope that if the nearby dust was blown INTO the hole - then dust would also be blown OFF the rover

Doug

It looks to me like they went back in with the brush. Many of the features looked pitted rather than covered with dust.


Click to view attachment

Yeah, in hindsight NASA has surely brushed at least one RAT hole.. So ignore what I wrote about whatever, blah blah

Back in with a brush and made it filthy? I dont think so. The clean rat hole is before the dusty rat hole chronologically. Dust deposition makes a lot more sense to me

Doug

Doug:

It looks less like dust deposition to me than the matrix breaking up, with the smooth surface disintegrating into clumps. At the risk of setting another wild goose chase off, I wonder whether static charges could have built up during the RATting which made the very fine particles dance about. I have yet to be convinced about macro-scale aoelian effects (microscopic dust layers, fine - it's just the big chaps that I have my doubts about!).

Bob Shaw

I'll have to stand over in the confused side of the aisle, too. Initially I saw this and thought "cuttings blown in", but I swear, the surface does look pitted and eroded. Thsi may be an optical illusion, and I'm waiting for more MI's.

--Bill

Strange crack in the terrain -

http://marsrovers.jpl.nasa.gov/gallery/all...B1P1700L0M1.JPG

Doug

A 360 degree panoramic view of Opportunity in the middle of the bedrock.

Taken with the L Navcam on Sol 550



jvandriel

Yes Doug, you can see it also in Sol550 jvandriel Panorama (Oppy traversed it) and in previous Sols I noticed other linear structures partially hidden, eventually related to this:
Click to view attachment Click to view attachment
My idea is that there is a large "macro" crack system connecting many outcrops, and running below the dunes (we should think to a unique cracked pavement partially covered by dunes, in fact ...
They must be deep too and I strongly suspect they are the cause of "minicraters", as suggested by this image of aligned collapsed sand holes on the side of that dune!
Click to view attachment
(I never trusted to minicrater explaination...)

Dilo:

Very interesting - a sort of limestone pavement, Karst style topography below the dunes... ...hmmm.

And I never really bought the mini craters, either!

Bob Shaw

There sure are a crack there djellison, and agreeing with dilo, I was never comfortable with the idea of miniature impact craters.
Opportunity did pass a series of sinkholes on the way to Endurance suggesting there are a karst bedrock below. The minicraters might be paritialy filled sinkholes and the cracked lines like the one djellison pointed out could very well have come from underneath.

Starting from Jvandriel last Pano, I made a magnified vertical projection (5 cm/pixel) in order to better identify the macro-cracks:
Click to view attachment
Here I tried to identify them, with possible (not sure) connections:
Click to view attachment
It seems they form an (approximately) orthogonal grid, with one of the two directions going toward Erebus...

Seems reasonable if the cracking is connected to the Erebus impact. Intuitionally I would expect cracking around an impact to be either radial (if caused by the uplift of the crater rim) or concentric (if caused by the overpressure/underpressure couplet of the expanding shock-wave).

tty

Not surprising or unusual. A strain ellipsoid shows that a deformation will produce a set of orthogonal fractures. Question is, what was the stress that produced this strain?

The anatolia-Karst lineaments are interesting because they have the appearance of solution cavities along a joint system. Interesting, because you need liquid water in quantity to dissolve the evaporite.

--Bill

Doug

Doug:

Well, I suppose we *did* see those un-enhanced Dust Devils...

Bob Shaw

Any information for the total lack of images from Sol 547-548 ?

I guess we'll see with the next update at JPL - bad uplink perhaps - low priority imagery - who knows.

Doug