Hmmm.

Frames of a colour view of Whim Creek are coming back, and here's what I've been able to make so far - quick go, not a lot of time to do this, but you get the idea...

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Lovely geology, but I can't get rid of that green area to the left. Give it another go tomorrow. It should be blue grey, I'm sure. The two James's will do it right.

However, in false colour it's clear that there's a difference in the surface material there, as if something has been deposited on the ground in some way..?

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Interesting..?

Discuss.

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Basically the same idea as for Anatolia at the beginning of the trek... it sounds reasonable to me.

Phil Stooke

The Sol-3029 5 x 1 mosaic of Whim Creek.

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And a False color view.

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How would that explain the lateral "wedge" or "dagger" shape that is narrow on the Cape York side and opens up into a wide expanse towards the crater interior?

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Could whim be the collapse of an air pocket created by an ancient impact that blew a huge rock apart? Oops, I'm suggesting the same thing Gladstone is suggesting.

The 'lateral wedge' could be part of a huge rock that was already fragile from other ancient processes or impacts? Okay, I'll keep quiet now!

Don't you think we have also to "connect" this to the existence of Cape York itself in some way?

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I'm in way over my head trying to outline geological scenarios. I was starting to do so in my post, and my thought was swallowed into the Gladstoner sinkhole!

"I wonder if it is actually a sinkhole filled with rubble..." - Gladstoner Post #452 PDT yesterday

I wondered the same about the tiny crater we rolled by recently - Sao Gabriel crater from Post #363

{edit}: I wondered if the impact that made the crater penetrated an air pocket or weak spot in the underlying rock that created a sinkhole look on the interior.

I'm chuckling right now because I feel like a little child that may or may not deserve a pat on the head from the elders for trying to grasp things beyond his education!

Those who prefer a bird in the hand to two in the bush...

You have to realize that the layered sediments that the dagger/wedge/notch is in are thinning in the direction of Cape York. Cape York itself is composed of Endeavour impact ejecta breccias. The cape rocks are overlain by wedges of sediments that thicken away from the cape.

Since the sediments thin to nothing as they approach Cape York, the Whim Creek structure fades away as it approaches the cape. This observation seems to suggest that the fractures forming the structure do not extend down into the older rocks of Cape York. It would be good to carefully image the rim rocks on trend with Whim Creek to determine if basement fractures are involved or not.


Looking at the bottom of the trench, I'm not sure that the blocks look like a "random jumble" to me.

Wow, Paolo, for being so data-constrained, you guys seem pretty serious about taking this Whim Creek mosaic.

Adding: and I'm glad you are; well, whoever is driving Opportunity now.

For a person that spent the past eight years of his life caring about this extension of myself on another planet, I find this statement quite insensitive. I'm not offended by your comment, just saddened: Oppy is "my" baby rover!

Paolo

At the moment Oppy has only downlink through ODY sitting still. The drivers now are: Khaled Ali, Tara Estlin, Julie Townsend (lead RP), and Ashley Stroupe.

Paolo

My fortune for a shovel. I'd love to have a look at the base rock under the collapsed rubble here. Hopefully Opportunity will traverse the length of the formation and maybe even try a wheel scuff at the apex.

This reminds me, Paolo, of something I've wondered about. We often see regions of hazcam images, and nav/pancam shots of the ground close to the rover, with areas shadowed by parts of the rover. When images were planned, did you ever do any modelling or calculations (or even use educated guesses) to estimate where shadows will fall? Or do the other constraints on timing rover activity always take precedence?

With the public jpegs, it can be hard to pull detail out of those shadowed regions, but of course you can do better with the original 10 bit images. Did you ever need to retake an image under better lighting conditions?

This an excellent question. Our simulation tools do allow to predict the shadowing at any specific Sol and time. There are some circumstances where the shadows are taken into account. Usually we try to avoid having MI images part in shadow and part in direct sunlight as this will make it difficult, if not impossible, to get details out of one region. Sometimes there are things we can do to mitigate this issue (like moving the time when these images are taken, or use one IDD configuration vs another one) sometimes we cannot. Regarding Hazcams I alwas try(ed) to increas the number of bits per pixel for the HAZ that will be partly in shadow. There we are usually limited by the downlink and you have to pick and chose between having more detail in the HAZ or having potentially one more frame in the NAVCAM or PANCAM. It is always a trade between quality and quantity. If I have reasons to worry about the state of the wheels at the end of the drive then I bump up the bps request. I don't ever recall using a different vehicle heading during a drive to avoid shadowing, but we did select particular headings to image features. For example, Sao Gabriel (I think) was done mid-drive and I did select a particular rover heading during the mid drive to avoid having the back of the rover to clutter the image.
For NAVCAM we also did move the time of image capture to have a better lighting, but that was a rare occurrence.

Paolo

Sol 3029 and 3031 Panoramic view.

Jan van Driel

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Added the images for Sol-3031.
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And the false color of this sofar...

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The Sol-3024 Navcam panorama from our current position.

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Two polar projections...

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Thanks as always for the fascinating explanations, Paolo!

The latest Planetary update is up. One odd comment that's got to be a typo:There's no way MARCI could resolve the edge of a dust storm sharply enough to be able to say it was 360 m from Oppy! The edge is probably much more diffuse than that in the first place. My guess is they meant 360 km.

Is the color asymmetry real, or an artifact of lighting? It looks like different materials on either side of Whim.

Gives me the impression of moss, especially the greener version.

But it's false color, and it's most definitely not.

Lighting may be a factor. Also wind may deposit materials preferentially on one side of the crick.

Think I've *finally* got the colour balance right(ish) on the Whim Creek pan - that (insert expletive here) green gravel on the left is now grey-blue, at last...

Work in progress...

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Nice color; those four new images don't actually link up with the earlier part of the mosaic.

Howard is right, there are maybe one or two more images that need to be taken and downlinked to be able to stitch those four new images together with the rest of the panorama. But very good work Stu!

They don't? They slotted right in.

Ah great. Knew it was going too well. That's what you get for making a mosaic at 02.30...!

Well, the stitcher tried its best, no doubt.

This is the view facing west and a bit down:

Right, I see it now.

Knew I shouldn't have stayed up to watch "Heat". Again.

The color assymetry is certainly real. The purple hues in the false color pancam composites have been frequently observed in the Burns formation, and have often been commented on in the science team's publications. The cyan colors seem to be typical of Meridiani "soils" rich in blueberries. I think fred's right. The cyan colored sediments are mantling the purple-hued rocks on the left side of that panorama.

My version of the sol 3024 panorama in circular form:

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Phil

Stu: Your images are always beautiful, but I really have to ask why would you want to remove color information from an image if that information reflected real differences in the rocks on Mars?

I understand that we amateurs have to work with uncalibrated images that may not always portray the true, spectral variances of Martian rocks, but if anything comes through on those uncalibrated images, it would probably be the spectral differences. As a scientist, I am always looking for ways to enhance the color differences, which is why I normally prefer to look at the false color imagery. I can understand trying to simulate true colors for the aesthetic human eye, but I think there is a balance where we should not discard useful information.

Actually that's a mistake - since they are uncalibrated the one thing you can't rely on is the apparent spectral differences. Only with the PDS data that we get six months later do you have something you can rely on.

Phil

Really? If that is true, I retract my statement. But, I have generated many images based on brightness ratios which appear very similar in their calibrated and uncalibrated versions.

The point I was trying to make was that the color asymetry across Whim Creek is real. Are you saying that it is not?

The asymetry (in false color) is evident. The physical cause seems to be a concentration of Burnes Formation hematite concretions on the Easterly side while the West seems pretty much Shoemaker eroded sediments.

The side-to-side difference is presumably real, but the exact spectral characteristics of each side can't be determined from the data we have now. I might be wrong, because I don't do anything with multispectral data, but I thought the images as released to us were subjected to an unquantified contrast stretch.

Phil

Phil's correct about the stretching - that makes it impossible to do accurate, quantitative spectroscopy.

But in practice, if the contrast and colour (spectrum) of the various targets are similar (which is probably often the case), then the relative exposures and stretching applied to the different filter frames will be similar. So I'd expect you could get some qualitative spectral information from ratios of the filter frames, at least as far as comparing frame ratios at different sites/targets.

Thanks

re the colours... just speaking personally, I am trying to produce as "realistic"* as possible a view of Mars, to share with people who read my blog(s) and who come to my Outreach talks. I can appreciate the usefulness of 'false colour' or even just stretched colour images, and find them useful *personally* for trying to figure out what I'm seeing in the landscape in terms of processes and differences in geology, but the average person who comes to my talks would be confused to hell and back if I showed Mars in an unfamiliar hue. So, again, personally, what I try to do most of all is try to get my colour images to look like the ones seen on the official NASA Pancam site. I very rarely manage that, because of the limits of my own equipment, software and skill, but I have fun doing it, and now and again, usually some time after midnight, at the end of a long work day, an image pops up on my monitor after a lot of work that makes me smile and think "Yeah, that's not bad... I like that..."

* ...which in itself is very subjective, I know. Let's not prise open that can of Barsoomian worms!

A bunch of images just showed up, including this Pancam L247 image (color section) from sol 3017. So it seems like Odyssey is still functioning well just ahead of the Big Event.

http://qt.exploratorium.edu/mars/opportuni...7M1.JPG?sol3017

Yes, Oppy, we know you're still there, and we won't forget about you!

Darn, is just like when the President or the Pope are coming, they block all the roads and there's nothing else on TV.

Paolo

NASA TV starting now....

EDIT: Hi Doug!

That's it, Oppy's not alone on Mars anymore!

Congratulations to Opportunity and all the engineers that worked on her. Today it feels even more incredible that she's still going on.