As an addendum, I did find it sort of amusing that one person on alt.sci.planetary challenged my news, asking me something along the lines of "How can you be seeing images from Sol 421 when the latest raw images at the MER website are for Sol 420?" I don't think I even had to tell him, someone else pointed him to the Exploratorium site.

-the other Doug

Um, yeah -- that's sort of my fault. I posted the news about Spirit getting a cleaning, and about the guys here spotting what appeared to be dust devils, to the Usenet newsgroups alt.sci.planetary and sci.space.history, where I also tend to hang out. Several hours later, I found an e-mail in my mailbox from Jim Oberg (who haunts sci.space.history, partially because it gives him a lot of good leads for his MSNBC news articles and columns), asking me for any details and official confirmations I might have about it.

I did give Jim O. the URL to this forum, and told him that while we could see the effects of wind in a lot of images from Sol 421 (including degradation of rover tracks and the cleaning of rover surfaces), I really didn't have an official confirmation of Spirit's vastly improved power situation. Come to think of it, I think we've just heard that statement from Doug and Pando -- I'd be curious as to where they got it, and when it was discovered... *hint, hint*... )

I rather specifically didn't post the URL to this forum on Usenet -- not that this isn't a publically accessible forum, I just didn't want to spur a flood of Usenet crazies into this nice, pleasant forum... *smile*... If there's one thing we do NOT need here, it's a flood of people insisting that every single rock in the MER images is actually a fossil, living plant or animal, and/or evidence of a third gunman hiding on the grassy knoll... *sigh*...

-the other Doug

That would be great, but... I seem to recall Mike Collins on Apollo 11 looking and looking for Eagle on the surface, and without a precise location the field of view in his sextant was just too narrow to find it.

I know what MRO's resolution is -- but what is the area of an MRO imaging "swath"? How many swaths will have to be imaged to find something that we don't have an exact location for?

The guys at JPL thought they had a good location on Viking 1, but MGS (which can effectively image the smaller MERs) hasn't been able to find it. They have less of a good location fix on Viking 2 and Pathfinder/Sojourner, and also their heroic efforts to find MPL failed. It's going to be hard to find those guys, much less Mars 3, for which I don't know if *anyone* has a decent idea of location.

Of course, we could always get lucky and find one or more of them by chance...

-the other Doug

I called it!

http://mer.rlproject.com/index.php?showtop...findpost&p=6353

-the other Doug

Damn typos -- obviously, I meant "bungling."

-the other Doug

I think ISS, while not very "sexy" as far as manned space flight is concerned, has been and continues to be a necessary "school" in long-duration manned flight. While the Russians already had considerable experience in long-duration flight, American experience in same had been limited to three Skylab flights, which all occurred more than 30 years ago.

The fact that the Russians had a lot of experience is not, in the final analysis, all that helpful to American planetary flight planning, because, face it -- the Russians haven't been forthcoming at sharing their findings, and the Americans had been reluctant to believe that the continuing repair efforts needed to keep earlier Salyuts and Mir operational were inevitable... I think NASA had always felt that the engineering issues with the Salyuts and Mir were typical of Russian bingling and not something *they* would ever have to face.

Now NASA knows better, and has a real basis of actual experience upon which to plan manned planetary missions. Experience that they perhaps would not have believed had they not earned it themselves.

If that is *all* ISS ever does for us, I'd say it was worth it.

-the other Doug

We could really use a fortuitous dust devil to pass directly over Spirit. I mean, they scour loose dust off of the landscape where they pass. If what you really want is a quick dust-off, I can't think of a better way of accomplishing it...

I can't tell if that's a crack or a cliff. You can almost believe that it's an upthrust fault that's formed a sheer wall several hundred kilometers long. And almost absolutely straight for a good length of it.

Would such a feature likely have been a product of crust shrinkage? Or maybe gravitational crustal deformation?

-the other Doug

With each close flyby of another of Saturn's icy moons, I'm struck by some similarities.

Each moon we've looked at closely (Iapetus, Rhea, Enceladus, et. al.) has shown features common to Jovian icy moons, plus some unique features of their own. That's to be expected, they're all unique worlds.

But we see a pattern of global stress fracturing on *every single one* of the icy moons that we've looked at thus far. Stress fracturing that seems non-common to the ways in which we understand fracturing on icy moons.

I'm struck by the images of Enceladus that have just come in -- that world looks like its surfacing is older but very similar to that of Europa. But there are cracks, both straight and arcuate, that do not correlate with the surface formation patterns. They seem to be stress fractures caused by a different process than the actual surfacing processes.

You see similar cracks and, well, distortion features on the other icy moons, including a hemisphere-girdling ridge that makes Iapetus look like a clay ball that someone tried to twist into two halves.

These distortion features could have different causes in each case, I suppose. But they look suspiciously like gravitationally-induced distortions to my (admittedly untrained) eye.

And, of course, you do have to evaluate the condition of the surfaces of the icy moons in the context of the presence of the rings themselves -- possibly evidence of entire worlds that were broken into particles no bigger than grains of sand. Possibly caused by impact processes, or perhaps gravitational processes. Or both.

You could explain all of this by unique gravitational resonances in the Saturn system, I suppose... though it seems odd to me that you don't see this kind of commonality of gravitationally-induced distortion features on Jupiter's icy moons. But when I look at the distortion features stratigraphically, it *really* seems to me that they overly *all* of the surfaces, from the oldest to the youngest, that we see on the icy moons.

So, we *seem* to have a stratigraphic process in which the Saturnian icy moons developed surfaces in ways similar to those we've seen in the Jovian moons. And then we see each of these moons displaying gravitational distortion features overlying surfaces of nearly all ages.

This would speak to some type of catastrophe (gravitational or otherwise) occurring within the Saturn system after its icy moons had developed their surfaces to pretty much what we see today.

So, I guess the question is -- what the heck happened at Saturn???

And when?

-the other Doug

I see what you're talking about -- almost looks more like a "stain" in the rock than an area of truly different composition (though that's hard to say for sure). The rock structure -- grain size, hardness, etc. -- looks the same both in the lighter "matrix" and the darker "clasts," which gives the impression of some sort of staining.

I'm not very clear on the location of the RAT hole in question, though. Is it in one of the rocks that appears finely layered, or is it in one of the rocks that looks more like the plains basalts? I'd have to think that the finely layered rocks are likely depositional, either aeolian or aquatic...

Doug
dvandorn1@NOSPAM.mn.rr.com

First, a few words about Endurance... it features several spots along the inner wall where scalloped edges of the rim have fallen into "slump blocks" halfway down the wall, right? We've seen several of them in the pans of Endurance.

We also see some terraces along the rim which display undersapping of soil beneath what are obviously five to ten foot thick layers of evaporite rock.

The rim has been degrading over millions of years, as underlying soil has been eroded away and layers of evaporite rock have come sliding into the crater's inner walls.

Now, look at an image of the Keratepe entrance path to Endurance:

http://marsrovers.jpl.nasa.gov/gallery/pre...rive-B150R1.jpg

Note how the edge of the primary contact between apparently evaporite rock and what lies below seems to scallop into the crater, rather than follow the curve of the crater itself. In other words, if the rim of the crater defines a concave curve, the edge of this layering unit seems to define a convex curve.

And there seems to be this little raised rimlet of exposed evaporite-appearing rocks right at the edge of this convexly-curved bedding.

It looks to me for all the world like Opportunity is traveling along the edge of a ledge that collapsed into the crater. Instead of looking at really, really deep layering of the underlying units, all of the evaporites in view look to me like they're shattered remnants of an evaporite "terrace" unit that collapsed into the crater a while back. So, instead of a beautifully layed-out series of in-place bedrock layers, we may well be looking at the partially-coherent, partially-jumbled talus of an infall of a layer that seems to be about five to ten feet thick at other points along the rim wall, but here is spread out by its slump to cover forty or fifty linear feet, all told.

Does anyone see what I'm seeing here?

Doug
dvandorn ((New Address To Be Announced))

Yes, the images of Spirit's heatshield show that it crumpled pretty good when it hit the rim of Bonneville. I don't think anyone will be surprised if Opportunity's heatshield did the same thing.

The point of interest at the heatshield isn't as much seeing how the shield held up as it is looking at the hole it dug when it impacted the surface.

There is *no* better way to look at and sample the materials in the top, oh, four or five feet of the plains unit (as it stands out there today) than looking at and sampling the ejecta from a hole whose age is known nearly to the second.

I recall the discussion about moving into Endurance, saying that if they decided to go into the crater they would do some exploring on the plains first, just in case they couldn't get OUT of Endurance. That included a trip to the heatshield and its hole.

Personally, I think what happened here was

a) the geologists began to become convinced that they *must* examine the rock strata in Endurance, that it's just too good an opportunity to sample layers that far down,

the engineers have started to see signs of old age in Spirit and are concerned that Opportunity may be heading for its own old age within the next couple of months,

c) the engineers think that the deep sleep mode will kill the mini-TES, sooner rather than later, and the geologists want to have it functioning while the examine the Endurance units, and

d) apohelion is coming for all of Mars, as well as seasonal winter, at both sites -- since no one knows if the rovers will be able to survive the winter, the scientists have to concentrate on their highest-priority objectives.

All of those factors argued for an entry into Endurance without doing any more plains research.

Doug
((New E-Mail Address To Be Announced))

I'll agree that the large-scale "layering" we see in the hills may be flood deposition or even ejecta deposition, but the fact that there seem to be layers of rock (regardless of deposition) in the hills, following specific rock horizons, does say something about the origin and history of the landforms there.

What I find even more interesting is the apparently fairly high population of finely-layered rocks in the hills. For example, here:

http://marsrovers.jpl.nasa.gov/gallery/all...62P2530R1M1.JPG

This doesn't look as much like the evaporites from Meridiani as some of the other layered rocks we're seeing in the Columbia Hills -- for one thing, it doesn't appear to contain concretions. But it's fairly obviously layered, and the grain size would indicate something a little different from standard sandstone.

Depending on the method of deposition you theorize for these rocks, you could be looking at true lacustrine materials deposited on the hills when they used the be the floor of Gusev Lake (prior to their uplift, possibly in a cratering event) or you could be looking at lacustrine materials transported to the Hills via glacial or other mass-movement action.

Doug
dvandorn@NOSPAM.mn.rr.com

I've been looking at some of the more recent Spirit images, and I'm seeing some really impressive layering at several different scales.

First off, there's these rocks (about one-fourth of the way from the top of the frame, one on the far right side and one on the far left side):

http://marsrovers.jpl.nasa.gov/gallery/all...00P2373L2M1.JPG

These rocks show fine layering. The one on the left side shows them perhaps a little more clearly, but the one on the right side is larger and shows more layers (though less distinctly). I can't tell the rock sizes conclusively from the context of the image, but the layers in these rocks appear to be very thin. They remind me of the layering in the Meridiani rocks.

We haven't seen this kind of layering, indicative of sedimentary rocks, much at all elsewhere in Gusev. I find this exciting. It's very definitely a different type of rock than we've seen down on the plains at Gusev.

Then there's this scene:

http://marsrovers.jpl.nasa.gov/gallery/all...00P2372L2M1.JPG

Not how there are coherent layers in the mid-field rocks that predominantly carry over from rock to rock. It's as if most of the rocks have been exposed and weathered out of the material making up the hill, showing that the hill itself was laid down in relatively thin layers and then eroded away. Yeah, some of the rocks have tumbled down to their current locations, but a lot of them seem to show in-situ, thin bedrock layers.

Finally, there's this scene:

http://marsrovers.jpl.nasa.gov/gallery/all...00P2373L5M1.JPG

It clearly shows the larger-scale layering of outcrops made up of rock layers several feet thick. If the rocks making up the larger outcrops are similar to the layered rocks seen in the above images, then we seem to be looking at the successive laying of similar-composition rocks with much finer layering within them.

I suppose we could be looking at wind-laid layers... but the fine layering in the rocks looks a LOT like the fine layering in the evaporite rocks at Meridiani. Any bets we find out the Hills were originally laid down as water-laden sediments?

Doug
dvandorn@NOSPAM.mn.rr.com

Well, updates are coming in somewhat slowly again, but they're coming in. What's not getting updated are the written descriptions of what's happening. Last I saw, both updates were on the order of a week old.

As for the linked image -- the more I look at those layers beneath the
evaporite layers, the more it looks like good old fashioned sandstone to me...

Doug
dvandorn@NOSPAM.mn.rr.com

I'm thinking that the lack of ejecta around *all* of the craters we're seeing at Meridiani (with the exception of Fram) has two explanations:

1) The craters were made a *long* time ago, possibly when there was still water overlying the site (though I don't at all insist on that). The upper layers of the whitish rock unit (the "evaporation layers") have all obviously weathered down significantly and have been covered with the basaltic sand that, along with the hematitic blueberries, makes up the dark regolith at the site. Any significant amount of ejecta made up of the evaporation layers has probably long since been weathered away. Hence the lack of visible ejecta.

2) I think a good number of the craters we've seen (including possibly Eagle, although I'm not as sure about that) are sinkholes and not impact craters. So the lack of ejecta around the sinkholes doesn't surprise me.

Now, obviously, Endurance is an impact crater, the crater rim morphology makes that clear. But I think it's quite possible that Endurance is simply old enough that the ejecta has all been weathered away.

I bet we find a lot of that on Mars.

Doug
dvandorn@NOSPAM.mn.rr.com

I think it's a great idea, Doug! However, I would also include a bunch of anaglyphs AND a pair of 3D glasses. I had a copy of the book NASA generated about the Viking landers (it got lost in a basement flood, unfortunately) that included both a rich supply of anaglyphs and a pair of 3D glasses in the back of the book.

In fact, if it's possible to manufacture a book that would successfully use the neutral-color polarization 3D anaglyph process, that would be even better. But IIRC, that only works with film projectors.

I wish I could find a pair of the 3D glasses these days -- I'd love to be able to view the anaglyphs that are being posted at the MER website, but I don't have the glasses I need to do so...

Doug
dvandorn@NOSPAM.mn.rr.com

It seems obvious from how Squyres was talking at the press briefing yesterday that they are *seriously* considering driving into Endurance. Those layers that lie below the high-sulphur whitish-rock layers are just too great of a temptation for Steve and his cohorts, I think. (I believe I'm going to start calling the whitish rock units "evaporation layers," since their high levels of sulphur and their high but inconsistent levels of such elements as bromine mark them as having been formed or altered during the evaporation of the body of water that used to overlie the plains.)

Now, I'm not positive that I see the extension onto lower-slope wall units of the darker, pre-evaporation layers that Squyres was talking about yesterday. I see something that could be mistaken for such an extension but that seems more obviously to be a portion of the rim that has collapsed into the crater. It's a scalloped-edge feature on the near wall to the right of the current panorama. But the edge of that feature, while it appears to continue the deep bedding that's visible a little further on, actually is the edge of a rim collapse. All we're going to see there, I'm afraid, is the basaltic sand that covers the evaporation layers out on the plains.

At least Squyres was pretty definite that Opportunity will be sent out onto the plains to check out the cracks and dimples (and maybe even some of the fretted terrain to the south) before being committed to a potentially suicidal entry into Endurance. And I was glad to hear that the heat shield impact point is targeted for a visit, too. It just seems to me that the heat shield had to dig a deeper hole than any trenching operation could generate. It will be very instructive to see if it penetrated through the evaporation rock layer or not (though, if that layer is as thick as it appears in Endurance's walls, I'd say that was highly doubtful).

Doug
dvandorn@NOSPAM.mn.rr.com

According to Steve Squyres at this morning's press conference, it definitely appears that the spherules are contained within the layered rock beds. Whether or not the rock beds originally were the host rocks for *all* of the spherules and spherule fragments within the crater and outside on the plains is another matter, but there is one good pancam shot showing a piece of Stone Mountain (formerly Snout) with four different spherules in varying stages of exposure from the host rock. Makes it pretty clear that they're embedded throughout the layered host rock.

Remember, the orbital imagery shows that the whitish rock unit, which is likely the same unit as we're seeing in the outcrop, is extensive in the Meridiani area and that it appears to have been re-exposed as a darker overlying plains unit has been weathered off of it. Perhaps the darker unit is not an overlying unit, but it what remains after the whitish unit weathers and leaves only the much more resistant spherules, which break down much more slowly and generate the darker soils that *seem* to overly the white unit?

One thing seems certain -- the spherules are much darker than, and weather much differently from, the underlying white unit. Which, as Squyres said, hints at a rather different composition. The best theories seem to be that the spherules are either blobs of magma that were ejected by colcanic or impact activity, or accretions of dissolved minerals from water than seeped into the whitish unit. Clues to look for will be whether or not the layering in the whitish unit seems to fold over the spherules (which will indicate that the whitish unit had spherules dumped onto it as he layers formed), or whether the spherules have remnants of the layering within themselves (which will indicate that the spherules formed within the whitish unit from precipitation out of water that has seeped into the bedrock).

- The Other Doug

I don't know -- it all depends on how you manipulate the color information, after all. It always seemed to me that the colors of Mars, from Earth-based telescopic imagery and from Hubble images, ranges from the rusty orange-red to a greenish-gray. The greens in the MEX images don't seem all that much *more* green than the greens I've seen in the Hubble images, for example.

Many of the color pan cam images from Spirit seem to show a greenish tinge to much of the landscape that looks not unlike the greens in the MEX images. Again, I think it's a matter of degree. It also may be a human-eye perception issue -- place a greenish-gray amid a lot of orange-red, and the greenish-gray appears even more green due to the contrast between the two colors.

- The Other Doug