MECA-OM Images - Page 8

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hortonheardawho Author Profile Page

Posts: 3465

Reply: 141

PostPosted: August 10, 2008 11:08 AM 

sol 73 OM pan:

And another that would benefit from EDFing.

hortonheardawho Author Profile Page

Posts: 3465

Reply: 142

PostPosted: August 10, 2008 11:16 AM 

sol 73-74 animation of AFM in action??:

Looks like crazy glue works better than pits and poles to immobilize the soil for scanning.

Er, it's awfully small.

hortonheardawho Author Profile Page

Posts: 3465

Reply: 143

PostPosted: August 10, 2008 1:57 PM 

sol 72 animation of, er, what?:

At first I thought this was simply a focus sequence and I intended to do another EDF -- but the changes over 3 minutes are just bizarre.

The spacecraft must have been a'rockin' to produce the soil and individual motions observed.


Posts: 3

Reply: 144

PostPosted: August 10, 2008 5:43 PM 

Strong magnet with the focal length changing to encompass the whole height of the pile. I don't think there is any movement of the material itself is there?

hortonheardawho Author Profile Page

Posts: 3465

Reply: 145

PostPosted: August 10, 2008 6:07 PM 

sol 21 73 animation of changes under the lander:

Er, brian, did you look at the animation?

Note the relative position changes of the substrate-soil contact edge;

Note the changes of relative position, shape and orientation of individual grains in the pile.

Please read the Flickr comments attached to the image.

hortonheardawho Author Profile Page

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Reply: 146

PostPosted: August 10, 2008 6:09 PM 

Ooops. Posted the wrinkling of "Snow Qween" on the wrong topic.

LWS Author Profile Page

Posts: 3062

Reply: 147

PostPosted: August 10, 2008 6:27 PM 

Hi Brian / Hort

There appears to be some movement but perhaps only in one or two small areas of the soil.

I've been wondering about movement in the OMs that use Magnetic substrates as It seems to me that the soil particles that were probably dusted onto the substrates hardly reflect what we are seeing in some of the OMs where there seems to be a coherent joined mass of soil in which few individual particles are seen. Sublimation of the soil appears to loosen the particles allowing them to be dusted onto the TEGA and presumably the OM substrates also, then, it seems that they join back together, and this seems to be not only on the magnetic substrates, as it is more noticeable there, but some of the other substrates as well, as seen in the relatively large "aggregated" soil particles on them. The water has already sublimated off. What is the energy for the subsequent joining of these particles into a coherent mass? Magnetism or some other force? Would surface soil and soil sampled from just above the ice layer both exhibit these same characteristics?

I suggested in an earlier post that perhaps we are now seeing up close what the Martian SODs in general look like and how they behave. Is magnetism the principal source of energy for the behaviour of the sods or is water and magnetism important in this or is there some other factor, that along with water and/or magnetism, causes the cohesive behaviour of the sods? Could these OMs and also Hort's RA closeup images be hinting to us that this is an area where further research is necessary?



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Reply: 148

PostPosted: August 10, 2008 6:59 PM 

Just a thought,

It would be hard to image the ability of the Martian atmosphere to get dust air borne if it had this much magnetism and cohesion. This type of polygon pattern ground would need to be different from other areas. Near surface water ice the only variable.

The images are fascinating


brian Author Profile Page

Posts: 708

Reply: 149

PostPosted: August 10, 2008 7:28 PM 

Hi Hort,
Yeah I see what you mean. There is a bit of minor movement. But we have material clumping under the influence of a magnetic force and some compacting/trepositioning could be expected particularly if there is any vibration either from external factors such as digging operations or even the changing focal length of the OM. Paramagnetic material would be more likely to move because of the weak attraction.

And mea culpa. I did miss the comments in Flickr.


Posts: 57

Reply: 150

PostPosted: August 10, 2008 9:44 PM 

To Horton, Re Reply no. 143 about Sol 72.

Yes this is interesting.

It appears that there is some movement. In particular the 3 pebble/conglomeration just above the centre and slightly to the left of centre is undergoing some wierd changes. The second image of the three makes it look like a dark bubble of some sort has formed on it only to disappear later. There is also the appearance in the same image of a line or rod running North East along the bottom left of the 'bubble'- at the north east end there is a very tiny ring of white spots. All of which are absent from the first and third images.

Despite this there are two comments I would have to make-
Years ago I had an interest in microscopes and the apparent changes in position and shape of items as either the focal point or the lighting source are moved can be startling.

Also the shadows on the bottom of all three images move counterclockwise as you progress - I wonder if this might help to decipher whats going on.


brian Author Profile Page

Posts: 708

Reply: 151

PostPosted: August 11, 2008 2:59 AM 

Hi Winston,
Reference your 147, I don't think we have seen any sublimation influence at work. The sample is sprinkled onto the exposed substrates and when the substrates are withdrawn into the OM anything larger than 200μ vertical measurement will be scraped off (unless it is in a microbucket). Then the sample swivels to the vertical to be imaged. Stuff will fall to the bottom of the substrate cell with the nature of the substrate determining what is retained and whether if presents as clumps or random small particles well and truly spread out.

I have difficulty in determining what substrate is imaged in some cases simply because the rotation nominated can be an offset from the example on the site. But Horts 143 is definitely the strong magnet.

The pixel size of the OM image is 8μm so unless the particle is reasonably large, say 10 times that then they will be fuzzy.

Barsoomer Author Profile Page

Posts: 344

Reply: 152

PostPosted: August 11, 2008 11:37 AM 

Re 143, perhaps the vibration is due to the TEGA vibrator being used at that time on the Rosy Red sample. The blurring at the bottom of the image does seem to indicate active vibration.

hortonheardawho Author Profile Page

Posts: 3465

Reply: 153

PostPosted: August 11, 2008 11:38 AM 

Sol 75 OM pan:

with links to visible / UV animations.

Brian, thanks for explaining the mechanics of OM sample preparation.

Do you have any idea what the substrate is for this sol 75 panorama? The rotational position of the center image is 10411.

What in particular is the substance that seems to coats only the right side of the cell and fluoresces very brightly. ( I am assuming we are not seeing some Martian substance glowing. )

There is a peculiar ( to me ) bright UV object in the upper left of the cell that simply isn't there in the visible.

I am totally out of my depth here. Where is a UV guy when you need him?


Posts: 161

Reply: 154

PostPosted: August 11, 2008 12:14 PM 

why is rosy red, so red? is this where the oerchlorates are from?

Is this (perchlorate), eating off the lettering?, from the om?


Posts: 638

Reply: 155

PostPosted: August 11, 2008 12:15 PM 


Looks like UV is a mineral thing. This page has links to minerals. Good stuff. No I am not a UV guy, but I did stay at a Holiday Inn Express last night.



Posts: 1

Reply: 156

PostPosted: August 11, 2008 5:54 PM 

Hi Hort.
That's OM 48 - silicone.


Posts: 708

Reply: 157

PostPosted: August 11, 2008 6:09 PM 

Hi Hort.
Re the flourescence, we don't know the UV wavelength used (there is a different response for short and longer wavelenths. In order to have a chance of identifying the materials we would need to know that and even then that would only reduce the list of possible minerals from 'lots' to 'many'. So the final ID would be a combination of data from MECA TEGA and OM.

They identified the perchlorates right off because they had a sensor that was optimised for that identification. That doesn't mean that that is the only oxidant present and there could be all kind of 'nasties' in the sample, not just perchlorates. But they did land in the polar region because water mitigates the effect of superoxides. It is here that some organics could have survived in/around the ice.

brian Author Profile Page

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Reply: 158

PostPosted: August 11, 2008 8:54 PM 

Found this link which gives a summary of UV responses. Might help with armwaving.

LWS Author Profile Page

Posts: 3062

Reply: 159

PostPosted: August 11, 2008 9:33 PM 

Hi Brian

Thanks for your explanation of the process of preparing the samples for examination by the OM and the AFM. Just thinking aloud and probably getting it all wrong. Does't this suggest that the chances of getting a real representative sample is quite low? Also, if you add this to the apparent fact that the samples are all being taken within the area of influence of the thruster jets, how representative, from a microscopic image standpoint are these images likely to be? Might there not be some important components of the soil missing?


brian Author Profile Page

Posts: 708

Reply: 160

PostPosted: August 12, 2008 4:33 AM 

Apart from the very surface layer I wouldn't think contamination from the landing jets would be likely. In fact the most likely contaminant was ammonia and as I understand it they did not see any. Physical impact visible to an OM - none, apart from the fact that the light dust cover was obviously blown away.

This is an optical microscope. They have to have a very limited depth of sample in order to be able to focus. Remember that everything that phoenix does is a function of pre programmed logic - this is not a remote controlled lander. They have very little scope for feedback from earth on the OM - if any. The scrape and position vertical approach is quite elegant limiting the particles to the focal range of the OM. The different substrates filter the subject material to an extent and overall the sample will be representative of the position and depth of the scoop in one very small work volume on a planet with the land surface area of earth.

With MECA/TEGA/OM data consolidated I believe that the conclusions that they will be able to draw regarding the makeup of the regolith and the aqueous/aeolian/chemical history of this small part of the surface will be significant.

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