http://hiroc.lpl.arizona.edu/images/PSP/release_007.html

No Ares Vallis yet (booooooo)

Lots of more varied northern plains in this one.

Doug

Yep... here's one that looks like a close-up of sandpaper... (click) ooh, here's one that looks more like glass paper, a bit rougher... (click) ah, now this one looks is grainy black and white, while (click) this one looks like grainy white and black...

Only joking... all valuable stuff, I know, but come on, "my" crater in Ganges is just over there guys, screaming at you to take its picture...

The last Northern Plains image (PSP_001497_2480) has another high-albedo crater floor in its lower right corner.

Does anyone remember a remotely "fresh" impact crater in any of the Northern Plains images? I understand the area we've looked at is minuscule, but if none appear, one has too look at serious surface compositional differences (very shallow ice? dust-covered permafrost?) as possible explanations.

That particular crater doesn't look fresh in comparison to others in the region, but it is indeed deeper than them. Looks like a (seasonal?) deposit of frost/ice has accumulated within, assuming that the prevailing wind direction is from the lower-left of the image.

The most interesting image for this release is this:

http://hiroc.lpl.arizona.edu/images/PSP/PSP_001482_2065/

A close look reveals a series of scattered craters along ancient small channels. Since the conglomeration of craters is on ground that seems younger than the surrounding area, this suggests that many of these small craters could actually be SINK holes.

Interesting - can you crop them out, please? I see a dust free (ish) landscape at the top, lava-filled valleys with very old crater hills bounding them in the middle, and a dusty landscape at the bottom.

The attached image shows, at the top, the old hills, with the clearly defined edges of the lava flows, and in the centre, a pre-existing channel which has been filled by lava.

Click to view attachment


Bob Shaw

Click to view attachmentHere are a few of the many that are all over the place. They tend to link some of the craters together. Note also that these channels cuts across both old and new terrain, as you identified.

Here's a link to a color Mar's Express Image of the same area. The caption clearly says water related, presumed to be from glacial reservoirs.

http://www.esa.int/SPECIALS/Mars_Express/SEMMBP1PGQD_1.html

It's a helluva thing when two people see such different things! I see a few semi-submerged channels in the 'new' terrain, and a heavily-cratered 'old' surface (in quotes because both are hardly young!). The linear features, where I see them at all, seem simply like random cratering (and where there are twin craters and the like, then I just see groups of secondaries on that ancient surface). The channels are part of the older terrain, and simply get filled by the new material, which is only a few tens of feet thick and sometimes gives a hint of the landforms below it - hence the channels which appear in the new areas.

It all looks so much more like lava to me than water-based morphologies - for example, look at the boundary in the top left corner where you can see layers, like one lava flow on top of another. At the 'shore' there are two distinct lobate fronts, too.

As I said, we're both looking and seeing quite dissimilar histories! Ah, the joy!



Bob Shaw

I realise they have their own spacecraft and all that, and lots of guys interpreting the images, but I have to confess that I rarely take ESA captions as being 100% reliable. They're overly keen on dramatic interpretations in my view, although I agree that Kasei Vallis is commonly accepted as having a watery history.


Bob Shaw

The problem with a lava interpretation is that such a flow would either completely destroy or cover up any hint of such channels, unless they were extraordinarily deep. The scale of these larger flows suggests any such lava formed feature here should be quite thick. Plus the craters are not anything close to random in my opinion. I see clear dentritic patterns here, with many craters or former craters along the paths. You may only see a few semi-submerged channels in the 'new' terrain (new and old are relative terms here), but I see many. The fact that they can be seen is exactly the whole point. We should not be able to see them at all, if this is purely a lava feature. Crater numbers under these circumstance cannot be relied upon to establish relative age--layering is more important.

Old craters should have shallow slopes. Many near the area that I drew the red lines do not. In fact, many of the slopes appear to be practically vertical. Lava flows can form similar structures, but the flows themselves would destroy our ability to observe any remaining underlying structures from satellite view. Also, many of the these small channels traverse across and sometimes almost perpendicular to the more apparent larger flow, the one that you suggest is from lava.

When there is plenty of evidence for water involvement in the creation of other regional structures, we need to consider how much water played a role here too. Catastrophic flooding can create depositional signatures that allow us to observe underlying features fairly easily. If groundwater continued to flow underneath, it would possibly undercut layered structures above given enough time. Karst landscapes can occur under a number of different scenarios. In fact, this could happen even if these larger flows are lava relics.

Regardless of interpretation, I merely point out that these are the most interesting images of the bunch from January 3rd. They deserve closer inspection and a more thorough analysis. Unfortunately for me, the file is too big--until I upgrade my computer. If water played a role, it does not mean that this is necessarily recent activity. They could be as much as a billion years old. But if they are that old, how did many of these craters remain such sharp features?

I independently decided it was the most interesting image of the bunch and downloaded it today. Tonight, I realized it was the same one you people were talking about. Every time I download one of these I run into the same problem; I get lost in the image and don't get around to posting a crop. I hope to correct that tonight.

This is some of the strangest Martian terrain I've seen yet. An anomalous concentration of scalloped craters are visible here. A fair number of them display bright rays. What's up with that? You'll need to see the full sized version to realize how common such craters are here, but I am posting a crop containing two representative craters at full scale. (25cm/pixel)

I also have a question for a HiRise person, or anyone else who cares to comment. This jp2 displays as a rectilinear grid of dots over most of the area. The entire right side of the full swath seems to be at a lower resolution than the left side. (The lower res part is not visible in the crop I am posting, but the rectilinear grid of dots is.) What's up with that?
Click to view attachment

Hmmm... ...those are seriously rotten craters! They're like Victoria, but as the newer one still has it's debris field then it's obviously a somewhat different story. Having said that, the degree of decay in the walls really does suggest a high sub-surface water content after all...


Bob Shaw

Lots of the HiRISE images are taken in a mode we refer to as "Boresight". Remember that HiRISE has 14 CCDs, 10 RED and 4 color, two each of IR and Blue-green. Boresight works roughly by taking a bin 2 or 4 image for the outside part of the image, and taking bin 1 for the red part of the center, and taking bin 2 or 4 for the color strip. This is done to save bandwidth frequently. So, you aren't just imagining it, it is real. Hope this helps!

But what's with the graininess in this image? It doesn't look like binning, it looks like ...well, grains? It looks like the effect of a very low S/N ratio.

Now that I see the higher resolution I understand a bit more. Keep in mind that the area is dark, and well, while the normal SNR of HiRISE is very good, it doesn't work as well when there isn't as much signal, AKA dark areas. That and we are still working on perfecting the calibration, which will help with that level of noise to a level. Hope this helps!

EDIT: I've been thinking a bit more about this, and have a few more things to say. It's a not-so-well known problem, but still public, that IR10_1 has some issues. It's a very noisy channel. In the early days of PSP, we were able to take pictures of it by warming up the whole camera to a certain point. This allowed for some readable images from IR10. However, we've since decided that it isn't really worth it, and this is because it makes the rest of the images appear very noisy. The images that are being released now generally fall under the time that we were testing IR10_1, to see if we could get anything out of it. However, it has the tendency to make the image appear much noisier, was the case with the image shown here. Hope this helps!

Click to view attachment

This shows elevation from images that I cut and pasted together. I added the labels too. Reds are the highest levels while blue are the lowest. Hopefully, this will give perspective on the Kasei Vallis image from MRO. Does anybody know approximately where on this "map" the MRO image was taken?

The latest version of OpenEV works for JP2 files on my computer. It's slow, but it works. Finally, I can view the larger files!

This closer look gives me a slightly different impression of the flow in Kasei Vallis. Some of the craters look different close up. Many are flattened with relatively level floors. The younger one shown by CosmicRocker is one of the exceptions; but even it is weird in it's own ways. I also found a deep crack or crevasse across part of the flow structure. I'll post a crop of it once I figure out how to capture images from the new close ups using this program.

I have only experimented with the export function in OpenEV_FW a bit, but under File/Export you'll find many options, but it seems to save the entire image. To simply save a jpeg of a particular view, I have found it easier to grab a screenshot of the view, and then edit it in Photoshop or whatever you use. I think ExpressView saves only your current view. Although it seems to crash if I use it too much, it is a useful program. I like it's ability to measure, but you need to use that cautiously, as it only measures pixels for these files, even though it allows you to select various units of length. Apparently the information needed for scaling in different units is not being passed to the program in these JP2s.

I noticed that the HiRise team has been linking each image to a HiRise and JPEG-2000 FAQ that mentions other software I haven't tried and haven't heard mentioned around here. I'd sure like to hear if any of these other programs are working well for others.

To save a crop of the whole image you must enable "Advanced Options" and "Window Input File" toggle buttons and then input the x,y coordinates and dx,dy size of the area you want to export in the "Start Line", "Start Pixel", "Num. of Lines", and "Num. of Pixels" fields.

Actually, once you've selected the "Advanced Options" and "Window Input File" toggle buttons, you can use your mouse to draw a marquee on the image, and OpenEV plugs the appropriate numbers into the coordinates fields.

Note you can also ask it to downsample when you export.

--Emily

Thank you all for the help.

I have crops now. Here is the crack that I mentioned.
Click to view attachment

Here are dunes from the same floor for comparison.
Click to view attachment
and

Click to view attachment

Is this Crater within dirty ice?

Click to view attachment

You know, posting .bmp files isn't all that sensible, they take up lots of space, don't show up as thumbnails and a lot of browsers won't show them, forcing you to view them with an external program. Any chance you could use jpegs or pngs instead?

When I first saw these, I thought they were dunes. Now that I found that crack, I'm not so sure.

Click to view attachment

Sorry about that. The program is new for me.

Yes, I can. But I'll have to reconvert the files. Can I edit the posts to reflect the new files or just repost them?

No problem, just a helpful hint. A lot more people are likely to look at it if it's a jpeg rather than a bmp.

You should be able to remove the old versions and reattach new ones in of the existing posts using the Edit button (then 'Full Edit' from the list)

James

Thanks, Tesheiner. So, that's what the input window is...duhh!

Emily, thanks also...clicking and dragging is so much easier. Who would have guessed that the mouse worked?

Infact, I'm going to pull them off the approved attachments list ( which for some reason, they are on by default)

Doug