On the Road Again - volume 8 - Page 7

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Author Message
Barsoomer


Posts: 344

Reply: 121



PostPosted: May 1, 2011 3:05 PM 

Ben, I think that is a hypothesis rather than a conclusion. It appears the pancam images of the area have not even been downloaded yet.

hortonheardawho


Posts: 3465

Reply: 122



PostPosted: May 1, 2011 5:13 PM 

Still only thumbnails available for the last couple of sols. Here is the plan for sol 2584 ( early tomorrow ):

4. What EDRs did we request?

Expected EDRs by sequence number and image type:

Sol Seq.Ver ETH ESF EDN EFF ERP Tot Description
----- -------- --- --- --- --- --- ---- -----------
02584 p0683.03 6 0 0 6 0 12 navcam_3x1_az_144_3_bpp
02584 p1732.03 4 0 0 4 0 8 navcam_2x1_az_234_3_bpp
02584 p2127.02 1 1 0 0 1 3 pancam_cal_target_L1
02584 p2275.09 27 0 27 0 1 55 pancam_albedo_pan_27x1_L1
02584 p2407.27 8 0 0 8 2 18 pancam_drive_direction_4x1_L2R2
02584 p2601.05 4 2 0 0 2 8 pancam_tau_L78R48
02584 Total 50 3 27 18 6 104

This is a somewhat peculiar combination of images.

It looks like a drive - but without the hazcam views usually requested.

The combination of navcam azimuth 144 and 234 pointing - plus a full pancam L1 panorama - suggests to me that the end of the drive will be about 15 meters short of the nearest rims of the 30 meter and 10 meter craters.

I was looking forward the the front hazcam views of the wheel. In particular, I wanted to see what happened to the two small dark spots inside the wheel visible on sol 2581:

hortonheardawho


Posts: 3465

Reply: 123



PostPosted: May 1, 2011 6:06 PM 

sol 2581 ( Apr 29, 2011 ) 1x5 R2 "stamp" panorama of "reticulated" soil:

The pan was taken about 60 meters into the drive. I will redo when the full size images are available.

Serpens


Posts: xxx

Reply: 124



PostPosted: May 1, 2011 7:18 PM 

Ben, good call, the planetary society monthly report (linked) has some information.

[link]

Their explanation is a bit light on. My guess would be a joint system where streams preferentially developed along the zones of weakness caused by joints. While this set is quite localised from HiRise it seems that there is a regional pattern extending into Endeavour crater and this joint set would have been a major control in the establishment of drainage patterns.

Ben, could you put your hydrology hat on and consider the pattern in the light of say a couple of metres of top cover eroded since the region dried down. Imagine the area more as a flood plain with consistent sediment transport with the underground aquifer preferentially following the joints. Water and sediment coming from the southern catchment. To me, the sediment deposition in Endeavour with the abrupt fall away to the deep end of the SE of the crater looks more like the result of a deltaic type deposition than aeolian dunefields. So what we have is similar to inverted river or stream beds delineating the joint set. This to me is compelling evidence of high volume, long lasting water.

Kye Goodwin. Terming these features as fracture fills is unfortunate as they have little in common with the ‘ridgeback’’ type fills previously seen at the top of the mound. The fine sand you refer to would have been deposited after the groundwater dried and desiccation shrinkage caused the initial cracks to widen.

Kye Goodwin


Posts: 1166

Reply: 125



PostPosted: May 1, 2011 9:13 PM 

I haven't seen Oppy's images of that patterned ground, which aren't on the Exploratorium yet, but I guess that the rover scientists must have already examined them. From the Planetary Society Report:

"That drive put Opportunity in the middle of an intriguing, "inverted relief" terrain area. "It's an area about 60 meters (196.85 feet) wide that features fractured bedrock with material deposited by wind," Arvidson described. "It [appears] that a little bit of water coming through the fractures cemented the materials and then wind erosion took away the softer bedrock, leaving the fracture standing as high areas, so it's kind of inverted relief," he explained. The rover stopped to take in the sights with some Pancam and NavCam pictures of the terrain. "We'll probably have them down next week. They're not super high priority," said Arvidson."

Or is that extraordinary suggestion about surface water based on just the Hirise image? I'm looking forward to seeing those rover images.

Ben


Posts: 2270

Reply: 126



PostPosted: May 1, 2011 9:43 PM 

Serpens; Actually not my call. Just what I read in the link.

I wrapped my mind around what you propose and frankly it seems to be a bit complicated.
I can accept GW recharge from a higher "catchment" area to the south but would guess that most of the flow would be below the surface and would reach the surface only during high GW levels similar to modern playas with occasional shallow lakes.

This downgradient ,subsurface flow could
could expand fractures by disolution and later sediment filling of the cracks could be concurrent with diagenesis that cemented the crack fill.

I don't think the fissure pattern is due to fluvial processes and I have yet to see evidence of a drainage system that would create a delta system of the size required.

I do believe Endeavour contained periodic standing water but not a depth that would create wave derived shorelines.

I am familiar with the Channeled Scablands in WA which were created by catastrophic flooding which could be the case here but I see no remnants of such in Meridiani area.

Actually in the limited reading I have done I find that many authors are not well versed in hydrogeology but maybe it doesn't apply on Mars ??

Serpens


Posts: xxx

Reply: 127



PostPosted: May 1, 2011 11:02 PM 

Hi Ben. My knowledge of subterranean hydrogeology is extremely limited and in this respect you the man. What I am proposing (probably naively) is that the fissures were tension joints and that at some stage the underground aquifer preferentially followed the joints, not that fluvial action caused them. I am not suggesting catastrophic fluvial events such as the breaking of the ice dam that caused the WA scablands or the channel erosion that caused the Grand Canyon. What I am suggesting is a widespread flood plain effect which results in a pretty flat and consistent deposition of sediment. To me the wearing away of the NW rim of Endeavour and the configuration of the inflow of sediment only makes sense as a flood plain (shallow lake playa effect if you wish). If the Endeavour crater infill were pure aeolian wouldn’t it have filled the crater to a reasonably level degree? On the other hand a lake deltaic effect with sediment flowing from NW to SE would result in the deep drop off we see in the SE.
I think that any evidence of fluvial wear on the NW rim is buried along with the remnants of that part of the rim, below the sediment with only the benches and truncation channels around the remnant rim providing a hint. Flood plains are pretty much channel free and erosion will have erased the superficial signs of flooding on the plains. Other hints are that Cape York itself is near surrounded by hydrated bedrock. The CY phyllosilicates seem to have been excavated by the now filled crater in the centre, unlike the deposits on other parts of the rim which implies that CY could have been over-run by water at some stage and that these phyllosilicates were protected by basaltic overlay following rim uplift.

As Bill so rightly said, we need to understand the plains leading to CY in order to understand CY. But I want to enjoy speculation before Opportunity arrives and my fragile bubble bursts.


Smile

hortonheardawho


Posts: 3465

Reply: 128



PostPosted: May 2, 2011 6:08 PM 

sol 2583 ( may 1, 2011 ) guestimated map position:

Still no full size images from the last two drives posted anywhere.

The position is based on the change in the drive index ( B600 to B6MN = 555 = 111 - 138 meters ) and the names of the post drive image sequences.

It appears that Oppy drove 400 meters in the last 3 drives. Cape York is now 4500 meters away, so that means Oppy could be there in 34 more drives. A drive every two sols would mean an arrival date around July 4, 2011. So maybe we can celebrate the 4th on the rim of Endeavour?

Kye Goodwin


Posts: 1166

Reply: 129



PostPosted: May 2, 2011 6:55 PM 

I'm intrigued by that Arvidson quote (see my 123). His description of how water coming through fractures might have created the present surface makes me wonder how the "mainstream" has changed over the years. When I started watching 6 years ago all the water activity was placed early in Mars' history, around 3.8 billion years ago, but Arvidson now seems to be talking about water that must have acted much more recently to produce a surface that is still present. Or do the rover scientists think that the plains surface we see is so inactive that it is billions of years old?

Maybe the old Ancient-Warm-Wet-Mars Theory has undergone a lot of conceptual creep since 2004. I wonder what they're thinking these days?

Serpens


Posts: xxx

Reply: 130



PostPosted: May 3, 2011 12:09 AM 

Kye Goodwin.

The induration that caused the inverted terrain would have occurred during the Meridiani water episode. A long long time ago. Ray Arvidson is not talking about a recent event.

Kye Goodwin


Posts: 1166

Reply: 131



PostPosted: May 3, 2011 3:56 AM 

Serpens, re your 128, "A long long time ago" leaves it pretty vague, but we all have to be vague because there has never been a single absolute date established for any rock on Mars. What do you think Arvidson is thinking, though, 1 million years ago, 10 million, 100 million, a billion, 4 billion? I thought that there was some theoretical reason why the warm-wet period had to happen really early? It gets less and less plausible as the imagined warm period approaches the time of the present cold, low-pressure climate. Having really early water explain shallow relief in the present surface only works if almost nothing has happened for 4 billion years, but the present surface this close to Endeavour must post-date Endeavour and a "long" period of erosion after the Endeavour impact as well. I guess that could all be really early if nothing has happened since.

hortonheardawho


Posts: 3465

Reply: 132



PostPosted: May 3, 2011 8:37 AM 

Here is the sol 2584 traverse map after the sol 2583 drive. My dead reckoning guestimate of reply 126 missed the sol 2583 position by about 12 meters and the sol 2581 position by about 4 meters.

sol 2584 ( May 2, 2011 ) "stamp" panorama in next drive direction:

The sol 2585 ( today ) drive is now done and the drive index increased from B6MN to B6Q4 for a move of 25-35 meters.

I think Oppy is now a few meters from the 30 meter crater on the left , officially named "Freedom 7". The crater on the right is named "Friendship 7".

There are still no full size public images posted since sol 2581. The internet tubes may need some cleaning.

Ben


Posts: 2270

Reply: 133



PostPosted: May 3, 2011 1:11 PM 

Arvidson etal in the Jan 2011 paper suggest the surface pattern between here and CY could be the result of lacustrine deposition.
Topographically this area appears connected to the even lower Endeavour crater which would mean the water in the crater would be even deeper and should exhibit shorelines??

They also speculate there is a change(reflecting environment) in stratigraphy in Botany bay and that the terraces may represent (more indurated) erosional remnants of Upper Meridiani beds.

Why would this be the case(maximum height of fluvial erosion) and wouldn't there be a few mesas of similar rock scattered across the plains?

Another point, the smectites on Cape Tribulation require large amounts of neutral water to alter the (basalt?) so where would this water come from at these elevated locations?

All in all very interesting summary but a few loose ends to be tied up which I hope we can accomplish Smile

Serpens


Posts: xxx

Reply: 134



PostPosted: May 3, 2011 8:37 PM 

Ben,
I think that the belief is that the phyllosilicates formed prior to the Endeavour impact and were incorporated within the uplifted (or perhaps even overturned) rim. Initially protected from the acidic waters by elevation and a protective capping which has since worn away by erosion or been pierced by small impactors over the past few billion years.

What was the title of the Arvidson paper you mention Ben? I was thinking lacustrian delta in the crater and a pseudo alluvial plain in the current area but the MER science team have a wealth of data to analyse as opposed to out 'looks like' approach. But the Phyllosian and Theiikian must have been pretty exciting times for this planet.

hortonheardawho


Posts: 3465

Reply: 135



PostPosted: May 4, 2011 6:13 AM 

sol 2585 ( May 3, 2011 ) 360 degree "stamp" montage between craters Friendship 7 and Freedom 7:

with a map link.

STILL no full size images anywhere since sol 2581. The problem is common to both Exploratorium and the official MER web site.

Today ( sol 2586 ) Oppy moved closer to Freedom 7 ( right side ) after taking a 4x1 L257R2 panorama of Friendship 7 ( left side ).

Ben


Posts: 2270

Reply: 136



PostPosted: May 4, 2011 1:44 PM 

Serpens; The paper is "42nd Lunar and Planetary Science Conference 2199.pdf
After you look at it , let me know what you think about their idea on the terraces and my above comment.

So the phillosilicates formed in impactite, basalt and the water came from ? precipitation, melting ice, space ???

hortonheardawho


Posts: 3465

Reply: 137



PostPosted: May 4, 2011 6:22 PM 

I wonder if this May 4, 2011 press release Mars Tribute Marks Memories of Shepard's Flight is part of the reason that the images have been embargoed for the last six sols?

The position on the sol 2585 traverse map is about a meter from my reply 235 sol 2585 map guestimate.

hortonheardawho


Posts: 3465

Reply: 138



PostPosted: May 4, 2011 11:31 PM 

sol 2586 ( May 4, 2011 ) L2 4x2 panorama in the next drive direction on Meridiani Plain, Mars:

with a location link.

After a 4x1 L257R2 pan of Freedom 7 Oppy will be on her way tomorrow ( sol 2587 ). It's not likely that the drive will actually be into the crater but more likely around the right side.

Quite a few images were posted this evening - including duplicates of previously posted images. I will play "catch up" tomorrow - even if no one else has the slightest interest in the Mercury project craters or the "reticulated" terrain.

Ben


Posts: 2270

Reply: 139



PostPosted: May 5, 2011 12:44 AM 

From images I hope Hort ,will soon post, I believe you can see that the reticulated terrain is probably not inverted topography , but is instead , intersecting linear sand ripples.

Nothing new in these craters , just the normal cyclic bedded material!!!
Makes me wonder where the older beds are if indeed we are going down-section.
Maybe these cyclic beds are just younger layers that drape the entire area.
See REGIONAL CROSS-SECTION in paper by Wiseman etal in the 2008 LPS conference 1806.pdf (I can't seem to move it here)

Serpens


Posts: xxx

Reply: 140



PostPosted: May 5, 2011 1:39 AM 

Thanks Ben, I have seen this poster session before. Their attribution of the terraces to erosional remnants of upper sections of the plains sediments seems a bit off the cuff and I actually think that this is an author group term for ‘We don’t really know just what the terraces and bounding channels mean at this time’.

The light pink in figure 2 is hydrated bedrock and when compared to your HiRise false colour it seems clear that the dark red is the gritty regolith that we have been driving over. The hydrated bedrock (light pink) could be the same hydrated material signature at SM that they picked up from orbit. Since we came down from the mound I believe that we have lost any correlation to the layers exposed in Endurance and Victoria craters. This new hydrated bedrock could well a reasonably shallow stratigraphic contact and since deposition came after the crater formed would pretty well conform to the crater slope. But the terraces are another matter. They could I guess be altered rim material that resisted erosion rather than indurated sedimentary deposition but they sure do look like a sandbar rip system, and the more I look at that ‘landslide’ in the SE corner the more I think I see evidence of water flow across CY leading to it. The suggestion that there is ‘a change in mineralogy, probably at a stratigraphic contact within Botany Bay’ could be significant as such could mark the edge of a permanent surface water environment.

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