The Stain

Thought it was time to give the "stain" its own topic.

I will start with a color analysis of the sol 2161 L257 image of the stain:


The Flickr comments explain the little color patches in the image and has a preliminary analysis.

I was actually surprised when the color of the stain turned out to be unlike anything else in the image.

I have located the most recent original data full filter images of the full sized stain and will do a multi-filter analysis over the Thanksgiving holiday.

Most peculiar to me is that even after a year the air fall dust has not obscured the "shain" enough to mask it's distinct color. How is that possible?

That's a really nice image, Horton! I can see the stain more clearly than ever before.

To me, the stain looks like a dark film over the light-colored dust grains. Does anyone else perceive it this way?


Nice color analysis. Nothing around Oppy has that color as you pointed out.

Keep thinking folks, there has to be answer to this query.


My reply taken from 'On the Road Again' of 11/22/10 below:

This is my first attempt to comment on the 'stain' as represented by horton's color images in 456 above and all the others representing it.

To me [IMO] this particular area may have been wet or damp longer if Oppy was tilted, on a particular cold night of frost or dew and perhaps an immediate dusty time contributed to soil adhering in this particular spot before sublimation took effect. Shadows of the boom may also have come into play and interrupted evaporation at that particular time and orientation causing a wet area to exist for a short period of time to then have Martian dust adhere to it.[?] Can't blow it away-seems to be struck there but then again it could be red residue which represents the same color as the surrounding soil. That's obvious, isn't it from horton's pics. I'm sure its Martian dust adhering to a wet spot and now stuck there like a immovable decal.

The panels have an even coating of Martian dust...all of us have seen that even accumulation difference in the past years and a good dust storm seems to keep its panels alive. We don't see piles of red dust anywhere on the panels as build-up causing this same discoloration.

At first I thought there may have been a leak from the panels themselves somewhere, but then we would see more of that leaky liquid as Oppy moved along its bumpy route and spreading red colored residue across its top. Can't be a leak, then.

The same for the vertical 'knob and post'...its been in a discolored pattern for quite some time. There may be a chemical reaction of the Martian dust and the material of the 'knob and post' giving it a strange eerie abrasive illness appearance we see in horror movies.

Thanks for the pic horton.

Just a thought, folks!

Hortonheardawho. What is the result of a similar analysis for that part of the deck over the first couple of sols at Eagle crater? It would be helpful to have an indication of the accuracy or otherwise of the USF moderator statements that it is just a clean patch of the deck.

We have seen many instances of a very smooth surface near the perimeter of outcrop blocks, and also at the bottom of some micro-channels. This surface is partially translucent or transparent because one can dimly see berries underneath.

I wonder if this is related to the stain, which seems to have a similar smooth appearance although one can see some grains underneath. Horton, could you do a color comparison to the very smooth soil? Of course, if it is transparent, then the color may be affected by the material underneath, which may be different. I don't know how you would control for that.

sol 2164-2221 ratio color by Horticolor™:

See the Flickr comments for a definition.

Always looking for new ways to display the data...

Unfortunately, ratio color can't be meaningfully created from JPG images because there is not enough precision in the JPG data.

I think this is yet another case for the unique nature of the stain.

There is a hint in the 2164 image that a "rind" rock coating has a similar ratio color.

There is a lot going on in the ratio color image.

For example, I processed the forward lit image first and thought for sure the very bright areas of the ratio color image that were dark in the natural light dark areas were a lighting effect ( most likely UV intensity related ) - but in fact the bright areas were still bright backlit - and in shadow! So there is something very interesting going on on the calibration rings.

Note that the dark "red" dust stays dark in ratio color and in both lighting direction.

serpens, I will do a "ratio color" version of some early images of the clean deck.

Barsoomer, I will try "ratio color" on the Anatolia trench too.

dx, I think water has everything to do with the oddities of Meridiani - including those on Oppy.

Although only one image was ever taken of frost on the sundial I have no doubt that it is a common occurrence on Oppy -- and on the surrounding rocks.


Wonderful ratio color technique you have employed to you're 2x2's. Anything to understand the 'stain'.

The absolute 1 other peculiar thing about this discoloration [or accumulation] is that its only located in 1 spot on the panel deck! Why is that? What presented an essence of change for an event to take place at this location and not another?

I'm still thinking. Its just looks like an oil spill on your concrete driveway from your friends' old Chevy 2-door coupe. :D

BTW horton, that clean deck early image will be an absolute must see. Its pristine when OPPY popped out of its cocoon, and she looks beautiful in fabulous black!

How to tag this mystery in back-time is going to be a consuming effort. There are a lot of pics to review.


sol 13 ( Feb 6, 2004 ) "ratio color" of the deck:

see the flickr comments for a number of amusing comments.

I think the deck is a light red in ratio color by Horticolor because of a specular reflection of the sky in the deck!

Anyway, the clean deck is not the "purple" of the "stain".

There was a discoloration on Spirit around Sol 1304. It gradually diffused into a wide area, becoming fainter, and eventually faded away.

This one looks like a clear case of wetting. There even seems to be a channel-like feature that may be an indication of runoff on the rover deck.

The discoloration is most noticeable in R7, and less so in L7. In that respect, it may resemble the stain.


Good hunting!!!Sure horton may color examine your findings.


Spirit sol 1312-1317 animation of changes to the dust patterns on the deck:

Notice that the dust looks like dust and behaves like dust.

IE, the wind blows and there are large changes in the patterns all over the deck. But when the Oppy stain changes nothing else changes around it.

This observation about the Oppy stain was the one that convinced me that the Oppy stain was "different" than dust.

Barsoomer, if you like I will do a "ratio color" of the Spirit deck - if you can find me a full filter view of the deck and post the sol number.

X-eye stereo comparison of recent navcam of the stain with one from Sol 1508 (pre-stain but dusty). The shadowing does not match exactly. Notice the pile of light-colored dust to the right of the "wire" in the recent image. To my eye, the stain seems to be higher in some parts of the image, rather than being flat throughout.

Horton, I agree that the earlier discoloration on Spirit is nothing like the stain. The image is from just after the Great Dust Storm, and clearly it involves a pile of dust from that. But it seemed to me that an early morning frost had wetted the dust at some time prior to the 1304 image. By Sol 1312 it had apparently dried out and gotten blown around. Most importantly, the discoloration did not grow in the aftermath of the event, if there was such; instead, it faded away.

By the way, does any of the crud here

match the coloration of the stain?

horton-Barsoomer et al>>>

Thanks for the pics. When I look at them in 10 and 12 above I have a notion that the 'heat' generated by the panels and flowing through the wires attracts small particles of Martian dust. We know by Earth observations that a wet-damp-frosty evaporating surface always has liquid residue in and around projections higher than the surface its on. So these edge surfaces hold more moisture. The heat generated for the panels through the wires may 'burn' and stain [discoloration]and cause the 'crud' [dust] as Barsoomer says, onto the surface of Oppy.

Just a thought, gentlemen.


Above is a fairly decent X-eye stereo view from Sol 13 of the wiring area to the left of the sundial.

For comparison, the above is a crop from one of Horton's recent images of the stain area link. Note that the stain is covering some bright low-lying fixtures, and higher peaks in those fixtures are peeking through the stain. (Horton, I hope you don't mind my using that crop.)

Above is a fairly decent X-eye stereo view from Sol 13 of the wiring area to the left of the sundial.

sol 2403-2414-2435 stain changes:

OK, I still can't see any changes to the red dust on the deck near the sundial.

IF the changes to the stain are due to a steady westward wind as Oppy traveled east for the last month THEN why hasn't any of the red dust moved eastward???

Perhaps the red dust is immobilized and the stain material isn't?

I think that I have demonstrated by ratio color that the stain is a unique material on the deck - so what sort of property would allow it to move on the deck while the red dust does not?

It has been scientifically established that all atmospheric dust is magnetic - and except for the strongest magnetic dust - that dust is red.

SO, perhaps the stain is non-magnetic and therefore easily moved about on the deck by the wind?

Note that when the rover was traveling backwards mostly south a steady west wind would have pushed unbound dust to the left ( looking back ) - which is what was observed.

We here on the blog ( yay team! ) have established that the stain appeared suddenly in the depths of Victoria crater so it is extremely likely that a material is not-atmospheric.

Now, the atmospheric dust has been found to be in the 1.5 micron range ( very fine ) - so the dark stain material would have to be even finer to be moved so easily by the gentle vacuum winds of Mars.

BUT ( and this is an important but ) there appears to be a "lumpiness" to the stain in the highest resolutions done to date - utterly inconsistent with a very fine material easily moved by the wind.

All of this leads to the assertion that the "stain" material can not be fine dust of any sort.

SO. what can it be? Ideas?

It sure would be nice if the "big guns" would weigh in on this trifling matter.

There seems to be a widespread assumption outside this blog that the stain is simply a clean area of the deck. I think this is one reason that it is not being looked at more closely in the mission observations.

It has been pointed out in this blog that the stain cannot be just a clean area because it (1) is seen to cover some deck fixtures and (2) has different reflectance properties, but perhaps the point needs to made even more strongly. This could be clearly established if a new stereo image, with the same quality as the Sol 13 one, could be taken of the stain and wiring area.

I think the "lumpiness" is possibly attributable to red dust under the stain, so maybe that alone does not rule out the stain being an overlay of blown dark fine dust. What does make it unlikely is the cohesiveness, i.e., the lack of dispersion and dilution as the stain is supposedly blown around. Also remarkable is the way the stain somehow was restored and even enlarged after it was once partially covered by blown red dust.

It might be fun to speculate about what kind of lifeform the stain might be IF it is alive (without any implied claim of such).

It would need some food or energy source. The only possibilities seem to be sunlight or the red dust. Even if it is photosynthetic, it seems to only spread where there is some red dust already present, so it presumably needs some component from there.

It appears that the stain is semi-transparent at shorter wavelengths, but opaque at longer wavelengths. This suggests as one possibility that the red dust contains the active lifeform and the stain is a "sunshade" produced by that lifeform to provide partial protection both from ultraviolet light and the cold. Clearly, not all the red dust contains the active agent because most of it seems inert.

The expansions of the stain seem sudden. This might be a false impression because of the spacing of images that are available, but we do have an example where an expansion of maybe a centimeter or so took place in the space of an hour. What kind of lifeform can expand at that rate?

As per reply 18,
If the stain is biologically created, the organism would have to have some kind of a relationship to liquid. Perhaps a perchlorate mix in the dirt allows the conversion of humidity in the atmosphere into an actual liquid water that is absorbed into the organism. The water is used with carbon dioxide and light to supply energy, and the perchlorate is excreted out into the soil to "trap" more water from the atmosphere.
Thus we see the expansion and contraction of the stain based on the water available to make the brine, and the ingestion and secretion of the perchlorate. The stain itself would be a kind of mud. This is consistent with how it looks.
I'm not saying I believe this to be true, but I love this kind of speculation.