MECA (microscope) Images Options

[elakdawalla]

Mark Lemmon's SSI image website mentions the sampling locations for some, but not all, of the OM samples. It's a place to start.

If we can get a consensus on what the samples are named, where they came from, and where they ended up, I'll be delighted to add that information to my workspace map.

--Emily

[peter59]

I have left out this interesting AFM image (Sol 124).
http://phoenix.lpl.arizona.edu/images.php?...679&cID=322
The image on the left is a particle of Martian soil observed with the atomic force microscope on NASA's Phoenix Mars Lander. For comparison, the image on the right is a type of terrestrial soil viewed with a scanning electron microscope.
The Mars image covers an area approximately 10 microns wide. This flat, smooth-surfaced particle is consistent with the appearance of soil particles from Earth containing the mineral phylloslicate, as seen in the left and right perimeter of the terrestrial image.

[CosmicRocker]

Wow! That is so cool to see. Thanks for posting it, peter59. I've been waiting to see another really interesting AFM image, and that comparison was awesome...really amazing to me, and it was the encore I was hoping for.

It is curious that their caption contained this phrase...

containing the mineral phylloslicate

Phylloslicates are a subclass of minerals that contains the clay minerals and others that are common on Earth, like talc, serpentine, biotite, and muscovite. Phylloslicate is not a specific mineral. I would love to know if this sample looks more like a clay, as their caption seems to be suggesting. I have no experience looking at these minerals on the micron scale. Can the AFM morphology actually help distinguish among the phylloslicate minerals?

[Gray]

Cosmic,
I, too, was a little puzzled by the wording of the caption. I also wondered about the intent of the terrestrial comparison. Was it to compare the ragged (weathered?) edges of the terrestrial phyllosilicate with the smooth (non-weathered?) edges of Martian variety? And what is that spongy grain in the terrestrial sample?

None of these are criticisms.

I think it's pretty amazing and extremely cool that there is a working AFM on Mars.

[01101001]

I, too, was a little puzzled by the wording of the caption.

The press-release copy, Mars Particle and Terrestrial Soil, Compared Microscopically, had slightly more words than the web viewer pop-up, but uses language unfamiliar to me -- but 'microboxwork' sounds cool.

The image on the left is a particle of Martian soil observed with the atomic force microscope on NASA's Phoenix Mars Lander. For comparison, the image on the right is a type of terrestrial material viewed with a scanning electron microscope.

The Mars image covers an area approximately 10 microns wide. The smooth-surfaced, platy particle is consistent with the appearance of phyllosilicate soil. The Martian particle resembles the soil on the left and right perimeter of the terrestrial image.

The terrestrial image shows smectite microboxwork separated from denticulated pyroxene by large pore space. The particles are in a soil sample of saprolitized clinopyroxene from Koua Bocca, Ivory Coast, West Africa. This image's field of view is approximately 23 microns wide.

It says "for comparison" (and not "for contrast") so I take it as: the similarity of the Martian grain to a known Earth phyllosilicate sample, is evidence that the Mars grain is also likely a phyllosilicate. The comparison focuses on the left and right perimeter of the Earth sample.

Edit: I think the other bit of evidence for the phyllosilicate interpretation came from the briefing at the end of September. Planetary News: Phoenix (2008): Phoenix Detects Falling Snow, Digs Up Evidence for Past Water, and Snares Mission Extension

A high temperature release of water vapor from one of the samples is, Boynton said, “most likely” due to a clay mineral “in the class of minerals called sheet silicates.” While the best known example of a sheet silicate on Earth is mica, in this case on Mars, he said, we're not looking at mica but a different type in which a form of water is actually in the crystal structure between the different sheets.” It’s the water between the sheets that makes the clay minerals “much softer” than mica. The team’s identification of a clay mineral is somewhat ambiguous, he cautioned. “There are a few other minerals that could release water vapor at high temperatures, but we think the sheet silicates or clays are probably most likely.”

During the press conference there may have been mention of that new-release AFM image, so it might be worth digging up a transcript, if it exists. The above source also has:

Bolstering the TEGA evidence for clay minerals, the microscopy instrument on MECA, has turned up hints of a clay-like substance. "We are seeing smooth-surfaced, platy particles with the atomic force microscope, not inconsistent with the appearance of clay particles," Hecht said.

[MahFL]

They need to stop using egg head lingo and write it in plain english.....lol.

Also its silly they use two different scale pictures as comparasions.

[centsworth_II]

Also its silly they use two different scale pictures as comparasions.

I've taken the left and right side of the Earth image and enlarged them 2+ times to approximate same scale as the Mars sample. (The Mars sample image is shown twice just to fill in some empty space.)

[centsworth_II]

Here I've isolated the top left part of the Earth image and adjusted the focus and lighting to approximate those of the Mars image.
It looks to me like this section of the Earth image shows six or so stacked plates and the Mars image shows a single plate. (This is my own very inexpert observation.)

[Shaka]

How could the AFM 'see' plates below the one it's 'riding on'?

[centsworth_II]

How could the AFM 'see' plates below the one it's 'riding on'?

It looks to me like the Earth sample is a stack of plates seen edge on. The Mars sample image looks to have been manipulated to give a side perspective view. I also wonder if the part I've colored violet here is part of the sample or, as it looks to me, the substrate on which the sample sits. (Again, not an expert. )

Note: nano-rover added for fun

[dvandorn]

What really causes me a wonderment is that these same two images, the electron miscroscope image of the terrestral soil and the AFM image of Martian soil, was used at a press conference back in September to show that *carbonates* were seen in Martian soil.

Is the phyllosilicate composed of carbonate minerals? Or did I hear something entirely wrong?

-the other Doug

[Shaka]

, as it looks to me, the substrate on which the sample sits.

Or is it just the 'zero deflection' baseline, below which the 'stylus' is not deflected?

[centsworth_II]

Or is it just the 'zero deflection' baseline, below which the 'stylus' is not deflected?

Hmmm. Here is a comparison with the first AFM image of a spherical Martian dust particle. The scale is about the same based on the dust particle (circled) being one micron (one micrometer) in diameter. So the question is, does the flat area (?) correspond to sample (which I doubt), to the flat area of the substrate (A), or to the 'zero deflection baseline' (B)? I've reached the depths of my ignorance.

Note: The description in the "first AFM image" link says the dust particle is in the upper right of the image when it is in the upper left.

[marsophile]

What really causes me a wonderment is that these same two images, the electron miscroscope image of the terrestral soil and the AFM image of Martian soil, was used at a press conference back in September to show that *carbonates* were seen in Martian soil.

Is the phyllosilicate composed of carbonate minerals? Or did I hear something entirely wrong?

-the other Doug

The carbonate detection was separate and independent from the phyllosilicate finding, and did not relate to the AFM image. The presence of calcium carbonate was inferred from (1) the WCL evidence of buffering at 8.3 ph, and (2) carbon dioxide gas evolved at high temperature in TEGA.