MI Remember that all the bays of Victoria were carved by aeolian erosion. As Doug pointed out, the process goes slow, but in 10's or 100's of millions of years, mountains of material can be eroded away.

I would have said those bays were formed by collapse - landslides probably localized by fractures. Wind just moves the debris around a bit.

Maybe the hazcams show the underside of the rock well enough to reveal its shape. - EDIT: the sol 1959 FHAZ images don't seem to show any pedestal.

Phil

What I see is a little lump, and maybe some hollow space before it, as if the rock tipped. The rock isn't resting on it.

RE: BI pedestal, etc....
Over the billion year (+-) life of this landscape there have been occasional hard shakes due to tectonic or impact earthquakes. This would certainly topple any pedestal and otherwise alter the resting of BI. This factor needs to be considered. As an aside, this type of short-term-rare but long-term-likely seismic shake would affect surface cracking in general...
(another side question: why haven't we seen any more "Anatolia" types of gaping cracks snaking across the landscape?)

Sometimes strange things can happen. I recall an article about boulders creeping across a dry lake bed in the California desert. Turns out that with a little rain, the super-concentrated brine acted as a grease, and the desert winds could blow the rocks across the lake bed.

Stitch of latest - sol1967 - Block Island MI images. Especially for you geologists to enjoy!!

1 (Posted below) - With min brightness, contrast and intensity adjustment from originals - Full size 1.4M at http://www.flickr.com/photos/kililpi/3797029362/
2 (Not posted here) - With BCI adjusted to give best bottom 2/3rds pic - on my screen! - Full size 1.4M at http://www.flickr.com/photos/kililpi/3797027720/


Click to view attachment

pedestal or not....(cont.)

here is a pancam view that has been processed using a (slightly modified) classic CLAHE technique
(seeing in shadows)

* The transition from shadow to light has a processing illusion that makes the shadow look depressed (ignore it)
* The other observation is that the jpeg compression in the uniform dark shadow becomes very apparent as the histogram is equalized...

my interpretation is that this just a pavement chunk that we have seen all over the planum. The pavement takes a jog to the left under BI so that it appears to be a vertical structure (i.,e. pedestal from the camera's POV) if you put your finger over that left jog under BI the illusion goes away and it looks like pavement. I am fairly confident that the left jog does not touch BI.

Another image from a different angle (move the rover) will add more data

...your mileage may vary...

Click to view attachment

cheers

I don't know if you've got it right or not, but your analysis is pretty much the way I see it. The imagery available is provocative, but we can't be certain that the feature being discussed is truly an erosional pedestal, protected by its caprock. I like your idea of using the MI for a closer inspection, but it would be very unusual for the team to use the MI for a task it was not designed for. I think it would also be quite surprising to see them using the rover to intentionally study "geomorphic" processes on Mars.

One would have to suspect that an overlying, resistant rock would tend to protect its base from aeolian erosion, but aside from this rock, we really haven't seen any other obvious pedestals beneath other resistant rocks in the region, or have we?

I'm going to jump on PDP's bandwagon, actually; that paving stone does look like it jogs to the left, and the underside illumination is tricky enough to play perspective tricks. More data definitely needed, though.

Re studying "geomorphic" features: CR, I think that if in fact this is a pedestal that would indeed be a significant finding worth detailed examination since it could tell us some things about the gross history of Meridiani. Not a Rosetta Stone by any means, but if the overall 'floor' has eroded since BI's been in place (however long THAT is) that would pose the question of why it's so generally uniform & level everywhere else we've seen. Eolian erosion usually doesn't produce flat surfaces; it removes it from one place & piles it up elsewhere (so I'd expect BI to have a tail dune). Furthermore, that might mean that even the local weather patterns have been extraordinarily constant for a very long time, and that might have some implications for the cyclical climate theories.

Whether it occurred before or after BI arrived, I thought the presence of the layer of loose berries on the surface indicated a meter or so of rock which once contained the berries having been worn away. Am I wrong in assuming that the loose berries indicate a 'proven' removal of about a meter of rock from Opportunity's stomping grounds (according to the mainstream hypothesis)?

I thought the theory here was that the northern plains (where Oppy landed) are blueberry-paved deposits formed as you described, with the deflation of a good meter or so of soft sulfate-rich sandstone that halted when the freed concretions provided an anti-aeolian "armor." The remains of the sulfate rock that was blown away composes the extensive ripple structures to the south (through which we're currently traveling). This terrain didn't have as many concretions buried in its sandstone layers, and so never developed the full armoring. Instead, ripple structures protect the remaining sandstone paving in the ripple fields from further erosion.

-the other Doug

Here's my attempt at an anaglyph from the sol 1961 pancam closeup of the big jagged pit:
Click to view attachment
This included a 20.7 degree relative rotation. The result still isn't perfect, but hopefully I've minimized headaches from viewing this...

Based on pics and Google Earth files posted in the Opportunity route thread, is Block Island just visible on a HiRISE image at full mag..?

Click to view attachment

Yes - it is - after all, Tim said it was

Really good - great sense of depth. Those two stalks sticking out at the bottom look really fragile. There's a couple or so more smaller similar structures around the edge of the hole. Fascinating. Anyone, any idea what sort of erosional processes might have been responsible?

Must have missed that post, sorry.

What are the HiRISE guys waiting to take a shot with Oppy?

Ok. Back to lurking...
Ermanno

I wonder if they started as products of the plunge onto Mars. Streamers of molten iron refrozen before impact. Or perhaps they were formed during the creation of the original asteroid. Of course, weathering on Mars would have taken place as well.

They're preoccupied at the time. But you're right, an MRO image of Opportunity at BI would be great.

"The powerful Mars Reconnaissance Orbiter (MRO) unexpectedly switched to its redundant Side B computer and subsystems before entering a protective safe mode on Thursday....'Taking the spacecraft back out of safe mode is one of the earlier steps in resuming full science operations, which is expected to take several days,' Webster added."

Catching up with recent drive direction mosaics.

All these link to the same page

Sol 1910

Sol 1912

Sol 1920

Sol 1942

Sol 1946

Sol 1947


James

And the Reeds Bay Pan:



James

C'mon guys, show us what's on the other side... and the underside...!

Click to view attachment

In case anyone missed it, from Maxwell's blog they may be considering just that:

What's to discuss? Oppy's sat at the corner of "No" and "Where", next to the biggest, most gorgeous frakking meteorite seen during the whole mission, surrounded by mile after mile of (bleep) all... what else are they gonna do?

Seriously, I know it's not a priority, and they have a lot of things to consider. The meteorite collector, rock hound and martian tourists in me are all just desperate to see the whole thing.

Been a while since we saw an outcrop this pretty...

Click to view attachment

Clearly should be called South America!

"Drive, Drive, Drive" Squyres said.

"Opportunity is going for the home run of Endeavour Crater."
http://www.planetary.org/news/2009/0131_Mars_Exploration_Update_Spirit_and.html ://http://www.planetary.org/news/2009/...pirit_and.html

Our final destination is still 15 kilometers away ... and many more un-seen wonders are waiting to be studied there

SCNR
Nirgal

There's a lot of interesting info about BI in the latest press release. For example, in relation to Rocker's comment above,

Also,

Yes, unlike many a press release, the JPL press release cited by Fredk is WELL worth while. And Alan, you have bragging rights for some time on UMSF -- that dark rock off to the South of Oppy's path has turned out to be quite a find!

Considering that the meteorite is sitting on a sandy, wind-swept plain, it's logical to assume the patterns were etched by blown sand. I had never seen an example of an Fe-Ni meteorite displaying Widmanstatten structure on a naturally weathered surface, but the full images and captions page from that press release contains a nice example found on Earth, on which they say the pattern was enhanced by sand-blasting.

I was hoping that the two hypotheses, abrasive wind blasting and acid etching, might be distinguished with the tools available to the rover. After doing a little digging around, it appears that is going to be difficult. The pattern essentially exists because of alternating crystalline layers of two minerals, taenite and kamacite. The pattern can become visible due to differences in their acid solubilities or their resistances to aolian erosion. It appears that kamacite's hardness is 4, while that of taenite is 5 to 5.5. Kamacite is also more soluble in acid solutions than taenite. The bottom line is, kamacite layers should be eroded or corroded more deeply, regardless of whether acid solutions or blowing grains were the cause.

There's an interesting discussion of BI on the meteorite mailing list. Look for the thread that starts out titled 'Must-see Martian in 3-D'.

I've finally bitten the bullet and done a colour image - I worked on SAmerica but I reckon it's just about worth having another version of, even if it's my first try. Colour looks quite good on my screen!! There's certainly a lot to learn - but it's heaps of fun....and to have fresh Mars pics to do it with!! With the likes of James, Ant, Stu, Astro0 (to mention a few!) there's high standards to aim for..... thanks for inspiring me you guys.

Will try to post now and again when I get time.

Click to view attachment

Awesome job Hugh! crisp, colorful, and relevant!

Thanks for sharing!

Thanks PDP8E! I'll definitely try and do a post or two when I can. Midnight Mars Browser makes it so easy to grab and review MER pics.

Just got back from work and saw your pic Hugh. Good job! :-)

This always amuses me. People generally see what they want to see.

That image that supposedly looks like South America was cropped. The actual outcrop extends further up and down, if you zoomed out. Because of the cropping of the image, the illusion is that the outline appears to be South America shaped. In reality, it is far different.

Regardless, it is a great image!! I like it too.

I saw a crocodile.

Oh. Ok. Just me then.

I can't tell if the "South America" outcrop pictured in the Sub-Frame EDRs is seen in any of the larger images.
If it is, I can't pick it out. I don't know if Sub-Frame EDRs would be called crops.
Click to view attachment
http://marsrover.nasa.gov/gallery/all/opportunity_p1969.html

I thought it was Spitsbergen...

Phil

The complete outcrop looks nothing like SA, but the crop does.

Well, now I see an ichthyosaur. I guess, technically a fossilized Martian Sand Ichthyosaur (Imaginashus runwildus). Very rare.

Very interesting discussion on how Block Island could have soft landed without a denser Martian atmosphere. The description by Sterling K. Webb was quite interesting and contradicts Matt Golombek and the JPL news release. Webb suggests that Mars' atmosphere is more dense than Earth's at high altitudes. Because of lower gravity on Mars, the atmosphere is taller than that of Earth.

Can anyone here support the arguments of either Webb or Golombek?

I can only make some very general comments. Webb doesn't present any actual calculations of trajectories. Golombek refers to such calculations in the new press release:

Surely these model calculations would include the difference in height of the Martian atmosphere, and well as many other details.

When faced with differing views, I'll go with the guy who actually did a calculation!

Webb is right about the density at higher altitudes - I thought that the cut over was somewhere in the 50-60km range but my memory might be off and the atmosphere extends quite a bit furthur out than Earth's. I've no problem with most of his calculations regarding survivability either - it is certainly possible for this class of object to survive to "soft land" on earth and the process that Webb describes could lead to a higher quantity of objects of this class surviving to land one way or another. The one thing he doesn't seem to detail is the expected terminal velocity - that would still be in the range of km/sec for something of BI's shape and density. That doesn't really affect his argument though - even at those speeds a metallic block like this would probably survive intact.

I think he does miss the boat a bit in terms of the things he says about how long these may have been around - we're seeing a very ancient surface and even if the rate at which objects survive is incredibly rare there should still be quite a lot of them around and for my money that is what we've been seeing. 4 billion years may be a bit on the long side but I don't see any reason why BI couldn't have remained on the surface for a significant fraction of a billion years if not a bit more.

Thanks Stu, MII et al for the encouragement. Appreciate it. I will definitely try to do some more posts.

FYI - We use Corel Draw for our business (just happened to start with it years ago) and so the image was produced using Corel Photopaint!

Not to mention that the effect of Mars' atmosphere on things falling from space is more than academic for those intent on safely landing stuff on the surface. I'm sure the profile of the Martian atmosphere is as well known to them as to anyone. (Of course, the situation a billion years ago is another matter, more open to academic debate.)

This doesn't really belong in this thread, but there's a new hirise view of Victoria...


ADMIN: Thanks fredk - see this thread

Oppy before the U-turn. Nice tracks.

Roy

Just about the best track pic I've seen.

After the sol 1973 bump, we've got this tantalizing quote from the latest Oppy update:

I know how much UMSF'ers like to speculate, so any guesses which features they're referring to?

Made in China sticker!