On The Road Again! - Page 21

More on the Google Mars "Scale Problem":

I tried creating an account for the Google Earth forum so I could post a query about Google Mars image scale - but a promised confirming e-mail has not yet been sent since I signed up 4 hours ago.

In the meantime, I did determine that the displayed scale is for the center of the image.

And when I tried my "3D" trick for this area to try to see some of the details for the sol 1818 crater, I discovered that the resulting 3D image was badly "tilted" - so the scale is not uniform in this area.

The surrounding area in the Endeavour 3D was "flat", so this seems to be a problem with the topology data specific to this area
- or perhaps the default viewing angle is not normal to the surface???

I will learn a little more about the program and see if I can force a viewing angle towards the center of the planet.

Bummer.

re 393 and Meridian dunes in general.
These dunes' surface texture and composition are puzzling, if we accept a normal, largely windborne origin.
It seems improbable that 'berries' would be arranged within or upon these dunes, as they are, by wind. In fact, dunes are usually the product of materials that have been eroded to fine enough size that they can be transported by wind and thus desposited in patterns. If winds were indeed strong to move the berries, why were they not all eroded into sand/dust?
This seems to leave two senarios. The berries formed after the finest dune materials were emplaced; or, a berry/dust/sand matrix which uniformly covered the etched terrain, is being eroded and exposed, creating an illusion of dunes.
James

Age of the crater is difficult. The rounding of many of the ejecta fragments suggest they have been subject to a long period of scouring .
Also the presence of an older crater could itself have modified the dune pattern.

There are a number of micro-craters in this area - including this 1/2 meter beauty smack on the crest of a dune:

I think that the micro-craters were secondary craters created by the creation of the 6 meter crater - and that this was a very recent strike - less than 1,000 years???

One of the interesting observations at the Spirit site is that the small soil disruptions caused by the rover have been competely erased within a few years, so my guess is that small disruptions planetwide should be erased in a time that is some function of the volume of the distuption.

Hort; After further review I also noticed chunks of angular ejecta resting on the dunes which also supports the late impact.

Now all we have to do is explain the rounded cobbles near the rim of crater

Any ideas fellows?

Age of the surface features is still a problem for me when using the young earth's generally,recent surface as a model.
It makes me think Mar's surface is generally very old.

James, re your reply 401: exerpt: "These dunes' surface texture and composition are puzzling, if we accept a normal, largely windborne origin." Don't accept a normal windborne origin. In time science will realize that Mars "aeolian bedforms" do not have anywhere near as much in common with Earth ripples and dunes as has been assumed.

One big difference already well established is that these ripples at Meridiani are extremely old compared with Earth's. Here's an abstract from this year's LPSC:

http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1973.pdf

A quote, "Equatorial TARS (transverse aeolian ridges) contain impact craters and give crater retention ages of 1 to 3 Ma."

And yet it is clear that changes to Oppy's ripples have taken place since the impacts that have disturbed them. There is no messiness left as the raw craters have somehow been smoothed and integrated into the scene:

The bright, sharp ripple crest in the image above was interrupted by the impact but a new length of ripple crest now seems to have formed following the top of the crater wall. In recent images of ejecta rocks from a relatively fresh crater thrown onto the ripples there are no messy bounce marks and some rock surfaces have somehow gotten to be flush with the ripple soil surface. My point is that the ripples change slowly during the long periods in which they are believed to be "inactive". I wonder if these small changes might over geologic time actually create the ripples, and the proposed exceedingly rare episodes of catastrophic Earth-like activity are an unneeded complication.

Hi Horton, may I ask if you have kept a log of micro craters that you have observed, no doubt you have viewed far more images along the trails than myself. I remember spotting a few that were probably made by pea or marble sized objects, falling at terminal velocity. I think these very small pits would not last more than a year or two. How fast do the dunes move across the surface? Also thinking that the dark bands on one side of a lot of the dunes might be a good tree ring indicator of sorts, winter, summer, winter, summer, etc. Not being a dune person though, might be barking up the wrong tree. I was thinking the dark lines are on the wind facing side, and as the dune is blown and moves in the other direction, the internals of the dunes structure are becoming visible.

Sol 1818-1820 ( Mar 6-8, 2009 ) view SE after 20 meter move NW:

Here is the sol 1818 view looking NW.

WTF?

Ever now and then the rover move makes no sense to me.

The sol 1820 move is a short drive away from the fresh crater - and in the opposite direction of Endeavour - and NOT in the direction of the "next drive direction" pancam panorama. There seems to be no "interesting" feature in the front hazcam in the 1820 area.

Any ideas about what's going on here?

Er, Kevin, my interest in Mars is that of a tourist, so there is literally nothing systematic about my observations. There are no logs, no graphs, no hypothesis and no predictions.

I will occasionally read a paper or two, think a bit about what I have seen - but nothing that is remotely scientific.

Mostly I have a tourist's collection of interesting snaps made whenever the bus stops.

OK, I think I figured out the reason for this odd move:

sol 1820 ( Mar 8, 2009 ) L0R0 of "dark soil":

Notice that the soil is darker in between the dune crests here. It is quite noticable in the Google Map of the area.

A few sols back an L257 4x1 panorama labelled "dark pit" was done of another "dark soil" area:

I think this move was an attempt to resolve the nature of the dark interdune soil. We may be here for a while.

Maybe they goin to take a closer look at this interesting light toned rock straight ahead of oppy now (a target of opportunity so to say ).

But its a real hard turn they took taking into account they try to reach a distant target in time (hopefully)

My guess is that they went backwards instead of forwards. They were/still are scheduled to do a pancam panorama of "Resolution Crater" today.
Maybe this will be part of the blooper reel.

North Rim of Endeavour:

East Rim:

But this?

See also:
http://www.unmannedspaceflight.com/index.php?showtopic=3215&st=105&p=70574&#entry70574

sol 1821 L2 8x2 of Resolution crater:

Yes, I think some of the rim peaks of Endeavour crater are visible. I will work on a map / vertical stretch panorama match later today.

Also, this is an L257R267 panorama, so when the rest of the filters are down I will do a color version.

There are several candidates at a heading of about 150 degrees.

But the shape of the peak seems to have changed in the short distance we have traveled - if we compare these two images:

Hmmm.

sol 1821 4x vertical stretch horizon panorama insert into Endeavour Map:

My best guess.

Notice that the "far wall" feature is in fact less distinct than the "near wall" features.

I look forward to the "official" map / pan.

Well, I'm still puzzled by the sol 1820 move.

Tosol is 1822 and no multifilter pancams have been requested - only a 5x1 navcam aZ 306 and a 2x1 L6R1 in the next drive direction. No MIs and no Hazcams . It can't be a mini-TES stop ( now 100% useless )...

Was sol 1820 a "pretty picture" stop - move back a bit to get a nice forground of tracks and crater with Endeavour on the horizon??? And then click, click, click - back on the bus???

Naaaah.

Kevin, Re your 407, you ask, "How fast do the dunes move across the surface? ". I've been following the issue in whatever free published science is available online (for example, the last 5 years of LPSC abstracts) and I am pretty sure that the rover science team would answer that this is still unknown, even within a few orders of magnitude.

Regarding the dark banding, I've seen the interpretation that you make: the banding is a section through old leeward depositional surfaces now being eroded on the windward side of the ripple, but I haven't seen anything much about this idea in the science. The banding is always on the east side and the prevailing wind direction is thought to have been from the east as the big ripples were built. I don't think that there has been any attempt to confirm by wheel-trenching that the banding extends into the interior of the ripples. Banding has not been evident where ripples have been trenched accidentally. The banding is easier to see from a distance, than close up.

Here's a line of inquiry that I've just thought of. Besides the large north-south oriented ripples at Meridiani there are many smaller ripples superimposed diagonally that are believed to be later structures built up by wind from a new direction. If the surface banding represents old layers now in the interior of the ripple then the smaller ripples should hide the banding in the underlying older structure. To me it looks like the opposite is true in this image:

The dark bands on the big foreground ripple seem to affect the color of the smaller overlying ripples. Hmm? I have no idea what the banding is but it seems from this evidence to be somehow SURFICIAL - something that happened after all the material in the large and small ripples had been deposited. I haven't yet been able to find another example as clear as this new one, but the smaller ripples often do not seem to obscure the banding as well as would be expected if they were truly overlying.

sol 1822 ( Mar 10, 2009 ) R0 5x1 looking west:

lots of banded dunes.

And here is sol 1821 L257R267 with 4x vertical stretch of several peaks of Endeavour crater:

BTW, the next drive direction L6R1 2x1 panorama is back towards Resolution crater!

There's a peak on a spur off Iazu crater which is the same distance away as the far rim of Victoria crater.
This feature is taller (-1251m) as compared to the far rim of Endeavour(-1310m).

However, the near rim of Endeavour crater lines up perfectly with this image.

The -1251 Iazu Spur peak is +1.4 degrees to the right of the near rim feature, or about 100 pixels in the above image. But we don't see it.

..far rim of Victoria crater.
I meant
..far rim of Endeavour crater.