NASA has just released a photo showing a part of the InSight Mars lander wet, like a cardboard box that came in contact with water (see the picture). What is that liquid?

enter image description here The Instrument Deployment Camera (IDC), located on the robotic arm of NASA's InSight lander, took this picture of the Martian surface on Nov. 26, 2018, the same day the spacecraft touched down on the Red Planet. (Source)


enter image description here

This is the object that looks like a wet cardboard box.

Regarding the theory of reflections advanced by somebody in a long answer,

I have to mention that the same image shows numerous reflections (see the picture below). None of them looks like a wet cardboard box and besides this I have never seen a similar case, when a reflection created the optical illusion of a wet cardboard box.

enter image description here

Evident reflections.

Using two more pictures posted by NASA, I made a gif that you can see below. It is evident that the theory of reflections, so insistently advanced by a user, is wrong. It can not explain why there is no change in the shape and size of what appears an area of cardboard that came in contact with a liquid. It is evident from the animation, which stretches across Sol 0 and Sol 1 (Day 0 and 1 on Mars, since landing), that there are numerous reflections and shadows that vary from photo to photo while nothing changes regarding the wet area.

enter image description here

Animation made of 3 pictures taken by one of the on board camera of the InSight Mars Lander on November 26 and 27, 2018. (Source)

Update, December 1, 2018:

enter image description here

Animation made of all available pictures taken by one of the on board camera of the InSight Mars Lander during 5 martian days. (Source)

Still no change in the size and shape of the wet area. There is an evident shadow above the wet area that changes. It is generated by the black object, in the middle of the image, which moves.

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    $\begingroup$ To be honest, I'd say the 'box thing' looks dusty & dull rather than wet. Besides, I can't figure out how is it looks wet by any means. $\endgroup$ – not_Prince Nov 27 '18 at 8:58
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    $\begingroup$ I'm voting to close this question as off-topic because based on the user's comment on another question "Honestly, this last mission to Mars, InSight, seems a big failure. The lander looks like it crashed. There are no updates about the fate of InSight in the last 36 hours which is highly suspicious." they do not believe the probe landed at all, and this question is an attempt to confirm a conspiracy theory, or a troll. $\endgroup$ – Organic Marble Nov 28 '18 at 22:35
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    $\begingroup$ Does anybody seriously doubt that the "wet patch" is simply the reflection of the black panel thing in the centre of the picture? It doesn't look like a wet box at all. It looks like a shiny thing with a black thing next to it. $\endgroup$ – Oscar Bravo Nov 29 '18 at 10:21
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    $\begingroup$ You continued denial of what is entirely evident in the photos that you have provided suggest (to me) that you have some ulterior motive beyond wanting an informative answer to your stated question. Ie. this a rant in disguise and you refuse to keep an open mind because the answer is not one you wanted. I'm voting to close on this basis $\endgroup$ – Jack Nov 29 '18 at 12:54
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    $\begingroup$ @Jack the OP is a frequent moon hoaxer, (1, 2) and the comments are meant to provoke. Don't worry about it. $\endgroup$ – uhoh Nov 29 '18 at 13:50

tl;dr: The wet appearance of the soft-sided hexagonal box-like structure is an artifact of reflection and interpretation. The object itself is a cover over the vacuum vessel of the seismometer Seismic Experiment for Interior Structure (SEIS).

It is called an RWEB or "Remote Warm Enclosure Box (RWEB) consisting of two Mylar sheets with a two-centimeter gap that will fill with Martian atmospheric gas (mainly CO2) which will be mostly motionless and provide an additional thermal insulation layer due to the low thermal conductivity of carbon dioxide." See below.

About the wet appearance:

  1. A dark but transparent Kapton layer has been applied on top of the shiny cover, giving it a wet varnish look.
  2. Wet surfaces have high reflectivity at glancing angles due to strong Fresnel reflection at those angles for low index of refraction materials. The photo in the question is viewing at a high incident angle.
  3. It's possible younger viewers haven't varnished anything and so are unfamiliar with what wet varnish looks like. Wet varnish has that "Kapton on Mars" look. ;-) The point being that while it may not look wet to some, to others, it does.

See comments below the question for context.

From Scientific American's NASA’s Next Mars Lander Zooms toward Laun

Close-up view of the Seismic Experiment for Interior Structure (SEIS), a seismometer provided by France’s Centre National d'Études Spatiales (CNES). Getting this delicate, precision instrument on track for flight caused InSight’s launch to be delayed from 2016 to next year. Credit: Barbara David

enter image description here

You can see in the pictures below that behind the seismometer there is a white dome. After the seismometer is placed on the surface of Mars, the robotic arm will pick this dome up and put it over the seismometer. An accordion-like ring will drop down from the dome so that it is tall enough to cover and protect the seismometer from direct exposure to wind and dust and some of the heating/cooling from day/night cycle.

below: The page https://www.seis-insight.eu/en/public-2/seis-instrument/rweb shows several more paper-like views:

enter image description here

below: From Spaceflight 101's InSight Instrument Overview "Wind & Thermal Shield – Image: CNES/InSight Project"

enter image description here

The LVL Sensor Package itself is further protected by a Remote Warm Enclosure Box (RWEB) consisting of two Mylar sheets with a two-centimeter gap that will fill with Martian atmospheric gas (mainly CO2) which will be mostly motionless and provide an additional thermal insulation layer due to the low thermal conductivity of carbon dioxide. Internally, the RWEB is also coated with VDA while the external face uses Kapton to prevent overheating during the deployment phase.

The vacuum sphere is a third layer of thermal protection for the VBB sensors and titanium washers provide isolation of the sensors from thermal variations on the sphere itself.

below x2: Click for full size! From Spaceflight 101's Photos: InSight Mars Lander Undergoes Assembly & Testing

InSight lander under testing

Before the application of the Kapton?:

enter image description here

InSight lander under testing

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    $\begingroup$ @RobertWerner there is no reason to expect two photographs, taken with very different cameras on very different planets with very different lighting to look the same. $\endgroup$ – uhoh Nov 27 '18 at 11:21
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    $\begingroup$ Younger viewers have worked with varnish! I'm only 41! $\endgroup$ – dotancohen Nov 27 '18 at 12:59
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    $\begingroup$ @RobertWerner Your denials are confusing. You have no prior example of the kapton-covered RWEB covered in dust in Martian lighting. The item you point out is undeniably the RWEB, which is undeniably coated in Kapton as described. At this point, what are you looking for? $\endgroup$ – Saiboogu Nov 27 '18 at 19:10
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    $\begingroup$ @uhoh regardless of the apparent problems in the question, thank you for compiling all these images and informations - they'll make for a great reference when the instrument deployment starts! $\endgroup$ – Jack Nov 29 '18 at 12:58
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    $\begingroup$ The dark patch hasn't moved, @RobertWerner, because it is a reflection of the environment. The specular highlights and shadows have moved because the Sun has moved. If it were a wet patch, the moisture would have spread through the card, and would not have been able to hold those sharp corners for 23 hours. $\endgroup$ – user20636 Nov 29 '18 at 13:09

Your "wet cardboard" theory is nonsense. Wet cardboard is not glossy or reflective, unlike the object shown in the photos.

This is a cropped version of your first image. No liquid in the world can make that kind of pattern. That means it is a reflection after all, and the larger panel on the right also shows a reflection.

enter image description here

As uhoh already showed in his answer, the object we're looking at is covered in kapton. Kapton is a glossy plastic film which is eminently capable of reflecting light.

Kapton roll

And some more rolls of Kapton, with recognizable reflections:

More kapton

  • $\begingroup$ These some more rolls of Kapton seems to be copper clad kapton, the copper is causing the reflections. The single roll above is kapton without copper. Copper clad kapton is used for making flexible printed circuits like the cable to the mole sensor of the insight lander. $\endgroup$ – Uwe Nov 29 '18 at 13:08
  • $\begingroup$ The theory of reflections is no longer credible, no matter how many answers you write and how insistent you are in trying to convince the people you are right. It is evident for me that you no longer believe in your own explanations. It is quite clear that none of your pictures with that Kepton looks like a wet surface. $\endgroup$ – Robert Werner Nov 29 '18 at 13:39
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    $\begingroup$ @RobertWerner None of the pictures of Kapton look much like a wet surface and neither does the image of InSight in the question. Your visual interpretation of the image is flawed - look at it again with an open mind to the help the answers are trying to give you and I believe it will jump out at you and become obvious, as with many optical illusions. Alternatively you can wait until the instrument deployment begins and the camera moves, but I've got a funny feeling you will still deny it. $\endgroup$ – Jack Nov 29 '18 at 13:56
  • $\begingroup$ the Kapton in the pictures doesn't have a layer of fine dust, which @RobertWerner seems to be interpreting as fibres in wet card. As such, showing how glossy and capable of environmental reflections it is, is tangential to the interpretation of the image he is proposing... $\endgroup$ – user20636 Nov 29 '18 at 15:14
  • $\begingroup$ @jack, unfortunately the camera movement was small, but he indeed still denied it. $\endgroup$ – user20636 Dec 1 '18 at 21:26

Further to @uhoh's "The wet appearance of the soft-sided hexagonal box-like structure is an artifact of reflection and interpretation." and @hobbes' "Wet cardboard is not glossy or reflective, unlike the object shown in the photos."

With today's (7th Decemeer 2018) release of images from the last few days there are a number of alternate views of the SEIS thermal cover. Here I've highlighted in green the panel in question, but taken from the opposite direction: enter image description here

-- from here there is no horizon reflection on that panel (the camera angle is too high to see the sky), so no dark/light border to be seen.

I've created another animation demonstrating the same effect - the horizon reflection creates a dark/light border that could be interpreted as a wet patch, but as the camera moves, so the reflection moves - in one frame, circled in sky blue, it passes between two of the holes, curving just under the leftmost hole with the reflection of the arm to the left; in the other frame the reflection of the sky has moved up above the tape line, and the robot arm reflection straddles the central hole:

enter image description here

Here is a closeup of the reflection of the horizon (or wet border), as the camera moves over a 5 minutes. I've adjusted the images to keep the reflection of the horizon (or wet border) steady. If this was a wet border, the gap between it and the row of tape would remain constant, whereas in reality it shrinks. I've circled a mark on the surface (visible in all the photos) that is conveniently on the reflection of the horizon (or wet border) - it's moving means it can't be a wet patch:

camera moves at last

In this animation of the first and third image, taken roughly a day apart, the arm has been moved. I've circled (in blue) the reflection of the claw in the dusty Kapton covered box.

The Claw! It Moves!!

Here's a rough idea of the layout of the area in question cgi

layout of the stowed lander deck

identifying reflections

the sky blue line shows what I believe to be the horizon, the green line the shaped plate on the manipulator arm, and red the arm itself.

Just what is reflected in the left panel is harder to determine, without knowing the geometry - if it's showing to the right of the camera, the deep blue is TWINS, and the yellow more arm or part of RISE. If it shows to the left, then deep blue is HP$^3$, yellow may be the SEIS wind shield.

For those who beleive "it can not be the reflection of the horizon as long as it does not start exactly in the point where the horizon touches the hexagonal hat": reflection of the horizon on a hair drier

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    $\begingroup$ Of course there's very little variation, not much in the scene is changing - in your own animation, in the panel to le left of the one shown above I can see what I interpret as the light changing on a solar array. Again in your animation, the change of light on the right of the two visible arm segments is seen just up and left of where the blue circle is in my animation. $\endgroup$ – user20636 Nov 30 '18 at 8:05
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    $\begingroup$ @RobertWerner you concede that there is a small reflection in the lower left, so what are you now suggesting? That the reflective material... transitions smoothly into wet cardboard? I suggest you look up No True Scotsman and Moving The Goalposts $\endgroup$ – Jack Nov 30 '18 at 8:32
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    $\begingroup$ If they were wet area on card, they would change, as the water water spreads through the card. It not changing is proof it is not a wet patch @RobertWerner. The horizon will not change, so the reflection of the horizon will not change. the plate on the arm will not change until the arm moves (at which point the camera will no longer be in the right place to take a picture for comparison.) so them not moving is proof they are reflections. $\endgroup$ – user20636 Nov 30 '18 at 12:24
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    $\begingroup$ Reflections are not dependant on the position of the sun @RobertWerner. $\endgroup$ – user20636 Dec 1 '18 at 13:39
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    $\begingroup$ nonsense @RobertWerner $\endgroup$ – user20636 Dec 1 '18 at 14:12

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