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[algorimancer]

Hematite at Gusev!

Perhaps not hematite, but it could easily be a cementation. It does look distinctly spherical. Here's a cross-eyed stereo perspective on it:



Interestingly, it seems to be lying in the center of a shallow circular pit. Possibly coincidence.

Here's a close-up:



The more I look at that close-up, the more interesting this thing becomes. Between the ball and the edge of the circular pit there are at least two distinct circular lineations. There must be a really nice geological term for this, but I don't know it.



Factoring in the rings surrounding the sphereoid, I think that there is no real doubt that this is in fact a cementation (concretion?), similar to the blueberries at Meridiani, but I suspect of a different composition. I've seen similar concretions in sandstone underlying limestone in central Texas. Further, to the best of my knowledge these things require water to form (at least dampness), so presumably this says something about the local geological history.

[Shaka]

Indeed.  Most of us have been so focused  with our industry-related pursuits that we haven't thought about such things since Geomorph 101 decades ago.
snip
>dropstone

***I speculate that it simply _looks_ like dropstone.  Remember that this is a fine-grained rock that has been gently sandblasted for millions of years.***

--Bill

EDIT: oops, I was thinking of something else.  It _does_ look like a dropstone.
"Never Mind..."
PS-- new L7/R1 Pancams are up:  http://qt.exploratorium.edu/mars/spirit/pancam/2006-02-10/

Hey, Guys, share the wealth! Can somebody put an arrow on a picture showing this "dropstone"? This would be my first on Mars!

[Shaka]

This panorama should be quite impressive at the end!
Currently almost all of sol 748's 6x3 frames have been downlinked -- L7R1 only, the "color" should be waiting on the priority queue -- and more shots are planned for tosol.

CODE

749 p2273.05 30  30  0   0   2   62   pancam_gibson_top_5cx1r_L257R127
749 p2274.05 66  0   0   66  2   134  pancam_gibson_left_11_pos_L257R127

Doug, I guess "a little bird" told you about it.

Hey, Tesh, does your portal into the secret codes tell you if some spectrometry has been started yet? That seems to be the key missing puzzle piece.

[tdemko]

Hey, Guys, share the wealth! Can somebody put an arrow on a picture showing this "dropstone"?  This would be my first on Mars!

It's right about dead center in this view, deforming the 3rd light layer from the base in the succession here:

http://marsrovers.jpl.nasa.gov/gallery/all...55P1214R0M1.JPG

It looks like it may have "dropped in" sometime after deposition of the 4th light layer...the "crater" it left is filled with some disrupted material, and it isn't until several layers later that they continue over it.

[Shaka]

It's right about dead center in this view, deforming the 3rd light layer from the base in the succession here:

http://marsrovers.jpl.nasa.gov/gallery/all...55P1214R0M1.JPG

It looks like it may have "dropped in" sometime after deposition of the 4th light layer...the "crater" it left is filled with some disrupted material, and it isn't until several layers later that they continue over it.

OH Yessss! 'Cause the light layer curves under it. Of course!
Thank you, Doctor. We do have fun in this forum, but having a professional along makes things so much clearer!
Tell me, what would you say are the key issues that need to be investigated now at HP?
Does PM offer other enticing questions?

[SteveM]

I dont believe it adds noise - but depending on Iron content, a Mossbauer Spectrum could take 3 days - perhaps even longer.

The APXS is still fairly sharp - much longer half-life on its source.

Doug

Assuming the false counts and electronic noise are at a constant level, while the CO57 intensity is declining at a 271.8 day / 264.5 sol half life, the signal to noise ratio on the Mössbauer should be decreasing.

Since you raised the issue, what is the isotope (and its half-life) for the APXS?

Steve

[odave]

From the SS QnA transcription...

Steve: No, no, no, that's only the Mossbauer. Mossbauer uses Cobalt 57; the half-life is 271 days. We've been on the surface a little over two half-lives. The APXS uses Curium 244 which has a half-life of 20 some odd years, so ah...

Doug: That's probably not going to be a problem!

Steve: <laughs> I don't anticipate havin' a problem with that one.

EDIT: Wikipedia gives Curium-244's half-life as 18.1 years

This post has been edited by odave: Feb 10 2006, 11:03 PM

[dilo]

Sol748, NavCam...



South view, now with complete McCool hill.


East view.

[Guest_Richard Trigaux_*]

Have you seen this flat rock (bottom right)

It looks like the flat surface of a strata (seen fom above). But it is not exactly flat... if looks like a soft or molten surface which was hardened after.

What is it?
surface of lava flow?
Mud? But if so, disturbed by what?

[Tesheiner]

Hey, Tesh, does your portal into the secret codes tell you if some spectrometry has been started yet?  That seems to be the key missing puzzle piece.

The "portal into the secret codes" may be yours too.
http://marswatch.astro.cornell.edu/merweb/merweb.pl

Select a rover (MER-A=Spirit, MER-B=Opportunity), then the sol(s) of your choice and click on "Detailed report". Look under section "4. What EDRs did we request?" for the planned sequences. Among others, we have:

CODE

747 p1131.05 2   0   2   0   0   4    front_haz_idd_mb_doc_512x512x1_bpp_high
749 p1121.03 2   0   2   0   0   4    front_haz_idd_apxs_doc_512x512x1_bpp_high

I read that as fhaz images to "document" the ongoing work of an instrument, in that case the Mossbauer and APXS spectrometers.

[Shaka]

The "portal into the secret codes" may be yours too.
http://marswatch.astro.cornell.edu/merweb/merweb.pl

Select a rover (MER-A=Spirit, MER-B=Opportunity), then the sol(s) of your choice and click on "Detailed report". Look under section "4. What EDRs did we request?" for the planned sequences. Among others, we have:

wwwwwooooooooowwwwww! It works. And I didn't even have to enter a MySQL query! I don't even have to know what a MySQL query IS!
I have god-like POWER!!!
HeHe, just wait till that bully kicks sand on me next time.
The name is Bond...James Bond.

[Nirgal]

Sol748, NavCam...



South view, now with complete McCool hill.

very impressive view, dilo !

gives a real sense of standing there looking up at the Cool Summit

[Shaka]

Have you seen this flat rock (bottom right)

It looks like the flat surface of a strata (seen fom above). But it is not exactly flat... if looks like a soft or molten surface which was hardened after.

What is it?
surface of lava flow?
Mud? But if so, disturbed by what?

What would you see if you buried one of the common laminated rocks from the slope, so that its top surface was exactly parallel and flush with the sand surface? After a million years or so of the wind and sand eroding it, would it look different from this?
The edges of the rock layers erode at different rates, producing their complex shapes. Would not the top surface also erode at different rates, producing an uneven surface, with the low areas filling with sand, as here?

[Bob Shaw]

I didn't think of the subglacial angle, but that is a very sensible idea. I've seen subglacial rhythmites in Norwegian caves which looked much like this.

I don't quite buy the indurated-sulphates idea. Morphologically this formation practically screams "harder than surrounding rocks", which does not fit with the softness of the Meridiani sulphates.

tty

When water-saturated sandstone is cut after quarrying, the water migrates toward the cut surfaces bearing a variety of dissolved salts etc. The outer surface 'mineralises' and forms a hard sheath around the soft, though still consolidated, interior. Obviously, all the bedding etc is preserved.

Now, switch to Mars - different materials, same process. But add hundreds of millions of years of aeolian erosion, and the odd impact or muddy flood.

So, you end up with a degraded formation, with rather variable material strengths, leading to stranger than even the usually strange shapes that ventifacts enjoy!

The original deposition could be ashfall, dunes, or whatever, possibly into a pre-existing crater (as in the famous exhumed braided channels which are now exposed as ridges, their water-altered materials being harder than the surroundings).

Bob Shaw

[CosmicRocker]

Have you seen this flat rock (bottom right)
...

Good observation, Richard. I have been looking so carefully at the bedding in vertical sections that I didn't even notice that bedding plane staring me in the face. It's an important view, but I need to stare back at it for a while.