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sgendreau
@#$%^! I wasn't where I could listen, and now that I am, they've taken the webcast down.

Did anyone tape it?
Matt Lenda
Woohoo! I can finally talk about the gypsum! Been sitting on it since the day we got the first APXS data down from Homestake.

QUOTE (Stu @ Dec 7 2011, 04:04 PM) *
Basically KK asked if SS could give a complete, drive by drive rundown of Oppy's plans from now until January, and SS rightly said "no", cos, I mean, how the (insert own choice of word here) could he *know* that?

I mean, right? We didn't even know we'd stop at Homestake until the day we did. Tactical operations on MER is literally day to day with some kinda strategic magic wrapped it.

(Plus, literally down to the command level, MER's sequence execution is event-driven and less deterministic than that of, say, an orbiter. We let the rover make a lot of decisions!)

-m
Mongo
NASA Mars Rover Finds Mineral Vein Deposited by Water

Wow! This is AMAZING. The discovery of a vein of gypsum has to be one of the very top-ranked mineralogical discoveries made by either of the MER rovers.

So where does this rate among areologists, compared to the numerous other MER discoveries? I'm guessing top three for sure and maybe number one myself, but I am no expert.
brellis
Looking forward to Emily's report on this one: Strong New Evidence of ancient water on Mars
QUOTE
After nearly eight years exploring the surface of Mars with the robot rover Opportunity, scientists announced Wednesday they have found "the single most powerful piece of evidence" yet that water once flowed abundantly on the Martian surface.

It must have gushed through underground fractures on the planet billions of years ago, they said, and as the water flowed, it formed a broad range of minerals that the rover has recently discovered near the edge of a crater that Opportunity has just begun exploring.

Led by Steven Squyres of Cornell University, the Mars mission scientists reported their latest findings from Opportunity's 20-mile journey at a meeting of the American Geophysical Union at San Francisco's Moscone Center.

In the course of its travels across the crater-pocked terrain of Mars' southern hemisphere - with many stops to investigate promising sites - Opportunity has already found iron and magnesium minerals that on Earth are known to form in water. But to Squyres and his colleagues, discovering the mineral calcium sulfate - gypsum, as it's most commonly known on Earth - makes it a "slam dunk case" for water.
Explorer1
Will Oppy's discoveries never cease....
One more for the drinking game?
Oersted
Nice write-up on MSNBC.com:
http://www.msnbc.msn.com/id/45587940/ns/te...e/#.TuCauGMr2nA

----------
After analyzing the vein with Opportunity's cameras and X-ray spectrometer last month, researchers concluded that it is gypsum, a hydrated calcium sulfate that on Earth is used to make drywall and plaster of Paris. The vein likely formed right where Opportunity found it, researchers said.
"There was a fracture in the rock, water flowed through it, gypsum was precipitated from the water. End of story," Squyres said. "There's no ambiguity about this, and this is what makes it so cool."
...
Both Spirit and Opportunity have found other good evidence of water activity on ancient Mars, including signs of hydrothermal systems. But the new discovery at Endeavour Crater is particularly convincing and compelling, researchers said.
"Here, both the chemistry, mineralogy, and the morphology just scream water," Squyres said. "This is more solid than anything else that we've seen in the whole mission."
----------
eoincampbell
Sheetrock for your Martian dwelling! smile.gif
fredk
As promised, there's a post-conference PS update with lots of quotes.
Marz
A few questions about Homestake:

1. the vein "likely formed where Opportunity found it", so was this fracture formed by the impact of Endeavor, or is Homestake more ancient than Endeavor and exhumed when the crater rims were formed?

2. iron pyrite (FeS2) is often found along with gypsum, so I was wondering if anything like it has been seen in the vicinity of Homestake?

3. I think gypsum can retain bubbles/pockets of the original water it precipitated from. What are the odds that a gypsum deposit a billion years old could retain a water sample, and would that be a holy-grail sample return in terms of characterizing the history of water on mars?
john_s
Good questions. For question 1), I don't think we know whether the breccias of Cape York are Endeavour impact breccia, or are breccias from earlier impacts, uplifted at the rim by the Endeavour impact. Cape Tribulation, with its much greater vertical extent, might have the answers. Either way, Homestake might be an example of post-impact hydrothermal circulation driven by heating from the Endeavour impact, an example of a process that has been modeled by several people over the years because it provides a possible warm wet oasis in early Mars history.

John
walfy
Managed to tease out this 3D of Boesmanskop close-up, from Sol 2798.

Click to view attachment
vikingmars
QUOTE (Oersted @ Dec 8 2011, 12:27 PM) *
"...hydrated calcium sulfate that on Earth is used to make drywall and plaster of Paris..."

Here you are : gypsum ...and coming from our Museum of Plaster close to Paris.
So... my home is made of Mars rocks ! laugh.gif
Click to view attachment Click to view attachment
http://fr.topic-topos.com/cristal-de-gypse...lles-en-parisis
http://www.ecomateriaux.net/%C3%A9co-mat%C3%A9riaux/gypse
http://www.ammonite-niort.com/gypse-fer-de...7167d7e59a92045
http://fr.topic-topos.com/gypse-en-macle-d...reuil-les-meaux
ngunn
Gypsum is so soft, how can it make upstanding veins?
Floyd
Crystaline gypsum is a lot differnt from plasterboard. Think of the crystals in the Mexican cave...
nprev
This is a VERY significant finding, obviously, but let's remember that all that's been apparently found is, well, some gypsum.

Extremely cool in its own right, of course. smile.gif
Mongo
I think that the importance of this discovery is not so much the discovery of a mineral probably formed in low-acidity water (that had been done first by Spirit, with Comanche) as it is the fact that the gypsum deposition was apparently done in situ. Comanche was moved to its present location from elsewhere, so there was little geological context to work with, whereas with Homestake, we have Endeavour Crater's rim and bowl to (I hope) make traverses over, in order to put this discovery into its spatial and temporal context.
ilbasso
QUOTE (Floyd @ Dec 8 2011, 08:36 PM) *
Crystaline gypsum is a lot differnt from plasterboard. Think of the crystals in the Mexican cave...


Nonetheless, gypsum is relatively soft relative to other minerals. It's "2" on Moh's Scale of Mineral Hardness, roughly in between the hardness of a pencil "lead" (graphite) and a fingernail.
marsophile
QUOTE (ilbasso @ Dec 8 2011, 08:49 PM) *
Nonetheless, gypsum is relatively soft relative to other minerals.


It's clearly harder than the rock surrounding it, as evidenced by the drive-over. Perhaps the vein has only been exhumed relatively recently in geological terms.
Stu
Two frame MI mosaic...

Click to view attachment

From here, I guess...

Click to view attachment
Marz
QUOTE (Stu @ Dec 9 2011, 04:41 AM) *
Two frame MI mosaic...


Bright inclusions on the upper-right might be more gypsum? And are those vugs in the lower left?

Thanks Stu!
Eutectic
QUOTE (ilbasso @ Dec 8 2011, 11:49 PM) *
Nonetheless, gypsum is relatively soft relative to other minerals. It's "2" on Moh's Scale of Mineral Hardness, roughly in between the hardness of a pencil "lead" (graphite) and a fingernail.


With loss of water, gypsum can change to anhydrite, which rates 3.5 on Mohs. That's still pretty soft, especially compared to minerals in basalt (5ish-7ish). Moreover, anhydrite is about 25% denser than gypsum, so the transformation of gypsum to anhydrite would be accompanied by shrinking rather than expansion, which would have been another potential way to explain the vein's positive relief.
Bill Harris
Good point, Eutectic.

Mineral hardness and weatherability don't always corrrelate. Remember, in some climes limestone can be a resistant ridge-former and in others a weak valley-former.

The important thing is, is that this fracture fill is composed of CaSO4 and we need to consider the geochemical implications of that...

--Bill
Oersted
QUOTE (vikingmars @ Dec 8 2011, 10:20 PM) *
Here you are : gypsum ...and coming from our Museum of Plaster close to Paris.


Hmm, that arrowhead is made of flint if I'm not mistaken. Or did I misunderstand something?
Stu
Surface detail...

Click to view attachment
Fran Ontanaya
Maybe the surrounding terrain wasn't eroded by wind, but just dissolved in water.
vikingmars
QUOTE (Oersted @ Dec 9 2011, 06:35 PM) *
Hmm, that arrowhead is made of flint if I'm not mistaken. Or did I misunderstand something?

This is the developed crystalline form of gypsum : the arrowhead (links added hereabove).
Gypsum arrowheads are very common here. We are being shown these since school in Paris and you see them oftenly when visiting the Paris underground quarries...
http://www.urban-exploration.com/index.php...;r=TOIT%20PARIS
Most of old houses in Paris and close to it (like mine) are made of rocks (taken from the quarries) and plaster made of gypsum (and also with a mix of those). Gypsum is also now transformed into construction panels easy to assemble and is considered as a very environmental-friendly material smile.gif
centsworth_II
QUOTE (vikingmars @ Dec 9 2011, 06:58 PM) *
Gypsum arrowheads are very common here....
I found this explanation of the formation of gypsum "spearheads" in the French Wikipedia:
"Le gypse en fer de lance est le résultat de la macle de deux grands cristaux lenticulaires."

Google translation: "Gypsum as a spearhead is the result of the twinning of two large lenticular crystals."


Can you imagine if Opportunity imaged this (from vikingmars' second link) laying on Cape York?!

Click to view attachment
CosmicRocker
QUOTE (ngunn @ Dec 7 2011, 05:35 PM) *
Gypsum is too soft, surely. Hardness 2. How would it stand up to erosion in this way?

QUOTE (ngunn @ Dec 8 2011, 06:02 PM) *
Gypsum is so soft, how can it make upstanding veins?

QUOTE (ilbasso @ Dec 8 2011, 10:49 PM) *
Nonetheless, gypsum is relatively soft relative to other minerals. It's "2" on Moh's Scale of Mineral Hardness, roughly in between the hardness of a pencil "lead" (graphite) and a fingernail.

QUOTE (marsophile @ Dec 9 2011, 12:23 AM) *
It's clearly harder than the rock surrounding it, as evidenced by the drive-over. Perhaps the vein has only been exhumed relatively recently in geological terms.

QUOTE (Eutectic @ Dec 9 2011, 10:44 AM) *
With loss of water, gypsum can change to anhydrite, which rates 3.5 on Mohs. That's still pretty soft, especially compared to minerals in basalt (5ish-7ish). Moreover, anhydrite is about 25% denser than gypsum, so the transformation of gypsum to anhydrite would be accompanied by shrinking rather than expansion, which would have been another potential way to explain the vein's positive relief.


Good question/s, ngunn. unsure.gif As ibasso pointed out, crystalline gypsum is quite soft as minerals go. You can scratch it with your fingernail. Marsophile hit the nail on the head. The absolute hardness of the mineral is not the key issue, it is the relative hardness compared to the rock within which the vein is enclosed.

Regarding anhydrite, that is also a good point, and one which might help explain Homestake's positive relief, but the vein has been identified as likely being gypsum (CaSO4.2H2O), and not anhydrite (CaSO4). From Salley Rayl's update, according to Ray Arvidson:
QUOTE
"Since Mini-TES [miniature thermal emission spectrometer] is not working, we really couldn't pin down the mineral phase based on the infrared. So the next best thing was to look at the vein with Pancam. It shows a dip at 1 micrometer, which is probably related to the presence of molecular water in the mineral, so it's calcium, and sulfur, it's water bearing. The best bet is it's gypsum, which is calcium sulfate with 2 waters in the unit cell," he explained.


QUOTE (Bill Harris @ Dec 9 2011, 11:31 AM) *
Mineral (hardness) and weatherability don't always corrrelate. Remember, in some climes limestone can be a resistant ridge-former and in others a weak valley-former. ...

That's the kicker, isn't it, Bill? In a real environment where mechanical abrasion isn't the only agent responsible for the wearing down of rocks, we need to consider several physical and chemical processes capable of breaking down rocks. It's sometimes tricky enough on earth, let alone on an alien planet. wink.gif If Homestake is embedded within soft sulfate sediments similar to those we have become familiar with on the Meridiani plains, perhaps this occurance resembles a gypsum crystal embedded within wallboard. wacko.gif
CosmicRocker
QUOTE (centsworth_II @ Dec 9 2011, 10:39 PM) *
I found this explanation of the formation of gypsum "spearheads" ...

Fascinating...I wonder if ancient peoples actually used these twinned crystals as effective weapon points.
Bernard
QUOTE (CosmicRocker @ Dec 10 2011, 06:32 AM) *
Fascinating...I wonder if ancient peoples actually used these twinned crystals as effective weapon points.



No, it's far too soft
fredk
An extreme range of depth in this anaglyph from 2800:
Click to view attachment
mhoward
I couldn't resist doing this one, because look at that view. Sols 2795-2800.



QuickTime VR version (5.8 MB)



QuickTime VR version (10.6 MB)

eoincampbell
QUOTE (mhoward @ Dec 10 2011, 09:00 AM) *
I couldn't resist...

It's quite brilliant, what a view!
Bill Harris
QUOTE (CR)
If Homestake is embedded within soft sulfate sediments similar to those we have become familiar with on the Meridiani plains, perhaps this occurance resembles a gypsum crystal embedded within wallboard
And in something semi-unrelated, remember the vugs found vugs that were found in the sandstone in Eagle crater seven years ago. The vugs were speculated to have been made by dissolved crystal with a tabular habit, possibly gypsum. Another puzzle piece fits...

--Bill
Phil Stooke
Here's mhoward's beautiful new pan in polar format.

Phil

Click to view attachment
ngunn
A couple of thoughts from the sofa: I hope the geologists will correct me where I'm off the mark.

1/ Homestake doesn't look like a feature produced by crystal growth into a loose matrix, like desert sand roses. It looks like it formed in a pre-existing crack in rock that was harder when it cracked than it is now in its weathered state.

2/ Erosion-resistent veins have been seen at Victoria and elsewhere, but the team are saying this is the first vein of gypsum found so far.

One lesson for me from all this: I didn't realise how mechanically weak the Meridiani stuff becomes when freeze-dried on the surface and that it could be significantly harder when not so exposed.
Bill Harris
QUOTE (fredk @ Dec 10 2011, 09:38 AM) *
An extreme range of depth in this anaglyph from 2800:
But if we forego the Big Picture and note the details, we'll notice that the Antenna Dust is less (Navcam stereo pair from Sol-2800):
Bill Harris
QUOTE (Phil Stooke @ Dec 10 2011, 02:04 PM) *
Here's mhoward's beautiful new pan in polar format.

Phil

Indeed, Phil.

It's interesting to compare your polar pan with HiRISE imagery of the same area:

EDIT: BTW, I just checked and the HiRISE map "north" and Phil's polar "north" are in close agreement, at least to shoot azimuths to specific features. Have fun...

--Bill
CosmicRocker
QUOTE (ngunn @ Dec 10 2011, 04:40 PM) *
... 1/ Homestake doesn't look like a feature produced by crystal growth into a loose matrix, like desert sand roses. It looks like it formed in a pre-existing crack in rock that was harder when it cracked than it is now in its weathered state.
2/ Erosion-resistent veins have been seen at Victoria and elsewhere, but the team are saying this is the first vein of gypsum found so far.
One lesson for me from all this: I didn't realise how mechanically weak the Meridiani stuff becomes when freeze-dried on the surface and that it could be significantly harder when not so exposed.

1: Homestake looks exactly like a vein of crystalline gypsum that grew within a pre-existing fracture. The rock wasn't necessarily harder when it cracked. You can form cracks in wet sand. I don't think you can conclude that the Meridiani sediments become weaker when they are exposed at the surface.
2: This is apparently the first vein of gypsum identified so far.

To further this discussion of mineral veins and their relative erosion resistance at Cape York, take a look at this pancam image from sol 2793. Note the sub-horizontal feature just below the center of the image. Here is a fracture in the rock with negative relief. Considering the proximity to the Homestake filled fracture, it seems likely that this fracture might also have been filled with the same mineral. I could be wrong, but Occam's razor suggests this to be the case. However, in this instance the surrounding rock is a tougher basaltic breccia. The vein is relatively softer than surrounding rock, so the vein is more deeply eroded in this case.
Bill Harris
Good observation. Here is another example from Sol-2786. Note the fracture in the lower left of the breccia block with the light-yellowish material still adhering to the wall of the fracture. My intrepretation is that this was a gypsum-filled vein which has eroded.

In addition, this region has a very complex genesis. We don't know what the hardness-- or range of hardnesses-- of the various units of breccia are. I would suppose that the surface material is composed of impact breccia and ejecta from many craters over a long time span. This breccia has been reworked, disturbed, transported, weathered and indurated countless unknown times. The ultimate in "folded, spindled and mutilated", I think we are looking at something unbelievably complex if we narrow the time steps enough.

--Bill
walfy
Microscopic from Sol 2800:

Click to view attachment
walfy
The adjacent micro from Sol 2800:

Click to view attachment

Some white patches in there. More gypsum, perhaps?
ngunn
QUOTE (CosmicRocker @ Dec 11 2011, 05:48 AM) *
The rock wasn't necessarily harder when it cracked. You can form cracks in wet sand.


OK, not necessarily.

I'm assuming these cracks formed, through both sediments and breccia, in response to major seismic shocks from impacts like Iazu. Mechanically weak materials (such as wet sand) tend to pulverise/fluidise in response to seismic shocks rather than supporting the propagation of coherent cracks. That's why an upstanding gypsum vein suggests to me that the sediments may have been significantly harder in their unweathered state. This would be consistent with Bill's point that hardness and resistance to weathering are two different things.

centsworth_II
A reminder of previous fracture fill seen by Opportunity:
Click to view attachment
http://www.jpl.nasa.gov/missions/mer/images.cfm?id=701

Those must be of different composition than the Cape York fill and may have formed by a different process. The first paper below relates them to rinds "actually developed only at the margins of fractures." It's interesting to note that in the upper right corner of the image above, there is a ridge on each side of the fracture which would seem to support the "rind formation" process. (Keep in mind, I'm a geological newbie).

A discussion of fracture fills seen by Opportunity starts on page 19 of this paper.

This paper discusses Earth analogs to fracture fills seen by Opportunity. (Which relate more to the fin-like fill seen previously than to the latest, gypsum fill vein seen at Cape York.
Bill Harris
QUOTE (Centsworth)
The first paper below relates them to rinds "actually developed only at the margins of fractures."
Very good! I'd lost and honestly forgotten about both those papers. Very fundamental references.

--Bill
PDP8E
Here is an animation from the pancam on Sol2801(?)
The IDD is in the frame and then a picture of the rock below (not sure of the feature name)
The filters are all right-eye
Click to view attachment


tim53
Hi Folks:

Because it's a nice round number, or maybe because we have so many overlapping navcam pans in this location, I thought I'd output a 1cm/pixel map of our current (and recent) locations.

best,
-Tim.
craigmcg
QUOTE (tim53 @ Dec 12 2011, 12:35 PM) *
Because it's a nice round number, or maybe because we have so many overlapping navcam pans in this location, I thought I'd output a 1cm/pixel map of our current (and recent) locations.


I think this should be called a splat-o-gram.
SteveM
QUOTE (tim53 @ Dec 12 2011, 12:35 PM) *
Because it's a nice round number, or maybe because we have so many overlapping navcam pans in this location, I thought I'd output a 1cm/pixel map of our current (and recent) locations.
Superbly detailed image! How did you do it?

SteveM
PDP8E
Steve, its all goes together with the right projection mapping software and enough navcam images
But I am pretty sure that Tim P. could have pulled it off just with scissors and elmer's glue rolleyes.gif
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