[X] My Assistant

[fredk]

If anyone knows of a better one that's publicly available, please speak up

The map that you used comes from Wray etal, GRL 36, L21201 (2009) I believe. Since then there was oversampled CRISM data, as described in this abstract. There's also a different looking (but very low resolution) map in this abstract, although that appears to be based on Wray etal.

I haven't seen a proper map that shows the signatures on CY using the oversampled data - maybe someone else can point us to something public? But I would guess that the Wray etal data that your overlay onto the route map used has been superceeded, and the team is using the better oversampled data to say we're near the orbital signature.

Edit: BTW, from the latest update:

The rover is positioned next to a large light-toned block of exposed outcrop. Previous Panoramic Camera (Pancam) imagery indicates mineral hydration in this block.

[ElkGroveDan]

Edit: BTW, from the latest update: The rover is positioned next to a large light-toned block of exposed outcrop. Previous Panoramic Camera (Pancam) imagery indicates mineral hydration in this block.

Someone remind me again, how do they determine mineral hydration with the Pancam? Which filter or combination of filters are used?

[Bill Harris]

Isn't Whitewater above Kirkwood in the section (or am I hopelesly confused)?

Righto. I was confused, tho not hoplessly (yet). Corrected the above post for posterity...

--Bill

EDIT:

...and then "uncorrected" it back to reflect the right lithologies.

Unless I'm terminally confused, Whitewater is the "light and fluffy" unit we've seen below the Kirkwood "blue and crunchy" unit Oppy looked at initially. Unless they've gone upslope and set up on one of the light and fluffy's up there.

Let me look and get back...

--b

[ngunn]

The overall scenario you described does appeal to me (as a non-specialist onlooker). I think there are probably other impactite layers above Whitewater as well. Soils sandwiched between caps and floors of impact origin could be good groundwater traps.

[udolein]

Why do we stay at Kirkwood these endless sols ?
Why not proceeding a couple of meters uphill into the smectite area as already noticed in CosmicRockers' post #330 ?
CoscmicRocker's waypoint image

Opportunity drove through that area between sols 2749 and 2751 10 months ago during it's drive to Greeley Haven without any deeper attention to this hopefully interesting area.

Cheers, Udo

[centsworth_II]

Why do we stay at Kirkwood these endless sols ?
Why not proceeding a couple of meters uphill into the smectite area...
Opportunity drove through that area...

No interesting features were seen as Opportunity drove through there, except perhaps for some gypsum veins. Where Opportunity is now there are tilted outcrops loaded with strange new "berries" and fine-grained mud-stone-like rock. Fantastic new discoveries to study. This is not a bird in the hand, this is a cage full of birds!

If and when the clays are found, it would be best to find them as part of an intact outcrop, not as a layer of dust or rubble, which is all that might be found in the red blotch areas.

(My non-geologist opinion)

[ngunn]

CORRECTED: Kirkwood <--> Whitewater

Even more confused now. I think you had the rock names the right way round before, but the light-coloured finegrained Whitewater is located above darker, spherule-rich Kirkwood.

CLAY: We may be right on top of it already. Crism only sees the big patches.

[Don1]

The rover drove through the clay rich signature last year, on its way to Winterhaven. It was pretty boring, so maybe the clay is mixed into the soil. They did see an outcrop called 'Hooggenoeg', which I think looks a little like the spherule rich outcrops seen from a distance. They also saw 'Sheba' and 'Kirkland lake' boulder field.

Last October 22nd, Road to Endeavor blog

Hooggenoeg image

Where the rover is right now may very well be a lot more interesting than the clay rich areas. It is definitely a little north of the clay rich area, although the story here is probably tied into the clays in some way.

[serpens]

Someone remind me again, how do they determine mineral hydration with the Pancam? Which filter or combination of filters are used?

They base this on a negative slope from 934 to 1009 nm (I assume with specific slope characteristics for imaged material as hydration shouldn't be the only cause of a 1009 nm absorption feature). All I could locate were abstracts.

http://adsabs.harvard.edu/abs/2011AGUFM.P22A..02R

[Ondaweb]

Does anybody know why Oppy went north around CY instead of heading south towards the apparently more extensive clay deposits there?

[Phil Stooke]

Because they had to find a north-facing slope to survive the winter.

Phil

[fredk]

There were some quotes in the recent PS update about the CRISM signatures and our current location.

"We’re right where CRISM says is the sweet spot for the clay minerals in this area," confirmed Ray Arvidson

the direct west route was taking Opportunity "right into the area where CRISM detected the clay signature,” he pointed out. "I think we're in the sweet spot"

"My sense for the campaign is to work our way up hill, because we can see other strata and this is aerially extensive and is probably the source rocks for the clays we’re seeing from orbit," he said.

So it sounds like this is the place to be. As I mentioned above, they may be working with better CRISM data than what we've seen.

[Ondaweb]

Because they had to find a north-facing slope to survive the winter.

Phil

Ok, thanks Phil.

[serpens]

Tom, very good overlay of the Route Map and CRISM map. I've been meaning to do that forever.

"Authigenic" in that the clays were produced relatively nearby, as opposed to allogenic where the clays were created in another area and then transported to this site via aeolian or even fluvial processes. We are on the same page, although in different paragraphs.

--Bill

I was actually thinking residual clay Bill. Clay components (possibly present in the mudstone on deposition or formed in situ) weathering out. One of a multitude of potential scenarios. Some of the discussions within the team must be fascinating.

[CosmicRocker]

... Since then there was oversampled CRISM data, as described in this abstract. There's also a different looking (but very low resolution) map in this abstract, although that appears to be based on Wray etal.

I haven't seen a proper map that shows the signatures on CY using the oversampled data - maybe someone else can point us to something public? ...

Thanks, fredk. I have been searching for the oversampled data but so far have come up short. I also recall those Arvidson quotes from Salley's update. It appears that the continuation of these outcrops to the south goes right through the old CRISM anomaly, so perhaps the oversampling technique simply expanded the area of detected phyllosilicates to these outcrops. There's no doubt that the people driving Opportunity know where they are going.

Someone remind me again, how do they determine mineral hydration with the Pancam? Which filter or combination of filters are used?

Dan: Here's a little more detail about detecting mineral hydration with the pancams. I think hydration could more reliably be detected if they could see deeper into the infrared band, but the R7 filter does see part of a water absorption feature. If it was still working I think the mini-TES would have been the best instrument to use to detect hydration.

A few recent papers have mentioned using the pancam filters to calculate a hydration index as serpens described. See the attached figure from Arvidson et al, "Opportunity Mars Rover mission: Overview and selected results from Purgatory ripple to traverses to Endeavour crater" JGR 2011.