APOD: Rock Fingers on Mars (2022 Jun 20)

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APOD: Rock Fingers on Mars (2022 Jun 20)

Post by APOD Robot » Mon Jun 20, 2022 4:05 am

Image Rock Fingers on Mars

Explanation: There, just right of center, what is that? The surface of Mars keeps revealing new surprises with the recent discovery of finger-like rock spires. The small nearly-vertical rock outcrops were imaged last month by the robotic Curiosity rover on Mars. Although similar in size and shape to small snakes, the leading explanation for their origin is as conglomerations of small minerals left by water flowing through rock crevices. After these relatively dense minerals filled the crevices, they were left behind when the surrounding rock eroded away. Famous rock outcrops on Earth with a similar origin are called hoodoos. NASA's Curiosity Rover continues to search for new signs of ancient water in Gale Crater on Mars, while also providing a geologic background important for future human exploration.

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Re: APOD: Rock Fingers on Mars (2022 Jun 20)

Post by JohnD » Mon Jun 20, 2022 8:51 am

Someone will correct me, but surely a "hoodoo" is formed where a harder rock preserves a column while the softer strata below are eroded away? The column is made of 'soft' rock, where if the suggested mechanism here is true, then the Martian column is harder rock!

This being so, and unless there is an already accepted name for such terrestrial formations, may I suggest 'oodooh'?
John

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Re: APOD: Rock Fingers on Mars (2022 Jun 20)

Post by orin stepanek » Mon Jun 20, 2022 11:31 am

anil-sharma-f27znidt1l0-unsplash.jpg
rock-sticks-Curiosity-rover-Mars-May-17-2022.jpg
Hmm! there is a small resemblance! :mrgreen:
udivlenie_8.jpg
Me; I'm not hanging around these snakes!!!
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Re: APOD: Rock Fingers on Mars (2022 Jun 20)

Post by JohnD » Mon Jun 20, 2022 1:19 pm

May I suggest an alternative way these were formed?

"Fulgarites" may form when lightning strikes the ground. Examples of Terrestrial fulgarites have a resemblance to what Curiosity has found on Mars:
Fulgarite 1.jpg
Fulgarite 2.jpg
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Re: APOD: Rock Fingers on Mars (2022 Jun 20)

Post by Chris Peterson » Mon Jun 20, 2022 1:43 pm

JohnD wrote: Mon Jun 20, 2022 8:51 am Someone will correct me, but surely a "hoodoo" is formed where a harder rock preserves a column while the softer strata below are eroded away? The column is made of 'soft' rock, where if the suggested mechanism here is true, then the Martian column is harder rock!

This being so, and unless there is an already accepted name for such terrestrial formations, may I suggest 'oodooh'?
John
The fundamental mechanism is the same, though. You have a column that doesn't erode as fast as the surrounding material. In one case because it's capped with a protective layer that is harder, in the other because the entire column is harder.
Chris

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Re: APOD: Rock Fingers on Mars (2022 Jun 20)

Post by Chris Peterson » Mon Jun 20, 2022 1:45 pm

JohnD wrote: Mon Jun 20, 2022 1:19 pm May I suggest an alternative way these were formed?

"Fulgarites" may form when lightning strikes the ground. Examples of Terrestrial fulgarites have a resemblance to what Curiosity has found on Mars:
Maybe, but it seems unlikely that you'd have multiple structures in the same area, especially given how rare lightning is on Mars (at least for the last few billion years).
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Re: APOD: Rock Fingers on Mars (2022 Jun 20)

Post by johnnydeep » Mon Jun 20, 2022 3:28 pm

JohnD wrote: Mon Jun 20, 2022 8:51 am Someone will correct me, but surely a "hoodoo" is formed where a harder rock preserves a column while the softer strata below are eroded away? The column is made of 'soft' rock, where if the suggested mechanism here is true, then the Martian column is harder rock!

This being so, and unless there is an already accepted name for such terrestrial formations, may I suggest 'oodooh'?
John
I like it - 'hoodoo' spelled backwards! (Which oddly enough, is equivalent to simply moving the first letter 'h' to the end!)
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Re: APOD: Rock Fingers on Mars (2022 Jun 20)

Post by MarkBour » Mon Jun 20, 2022 8:56 pm

I just went and looked at a lot of examples from Google image search. I thought they were mostly simpler shapes. Maybe they are as a rule -- but since we humans like to find and document the most extreme -- it seems that on Earth, we can get hoodoos in almost any tortured spire-like profile, as long as it hasn't broken yet. (The Queen's Head in Taiwan is a great example, and reminds me a little of today's APOD's shapes.)

In this particular case, I can imagine that the following sequence possibly occurred. If we look at the large rock right in front of them and imagine it standing up on its end, it would itself become quite tormented by wind over time. Perhaps it had a small base which included the two rock fingers and finally it broke off. If it rotated and fell forward, leaving behind the two rock fingers, I can see gaps on the larger rock that could have broken off that look like a match for the fingers. Measurements could prove or disprove this theory pretty easily. I can't tell from this perspective if the shapes line up or not. If that happens to be right, then the rock fingers, now exposed to the wind on their own merits, will probably relatively quickly erode to more boring shapes. The front one looks a lot like a bird perched atop a stick (or a King Cobra, as Orin noticed). I can't guess that it will last very long (geologically).

There's lots more to savor in this image beyond the two fingers. I really like the fisherman's hook shape at the far left.
Mark Goldfain

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Re: APOD: Rock Fingers on Mars (2022 Jun 20)

Post by mararcin » Mon Jun 20, 2022 10:11 pm

How long could organic material last on Mars today? Because of their size, I think they look like sticks. Am I alone in this?

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Re: APOD: Rock Fingers on Mars (2022 Jun 20)

Post by johnnydeep » Tue Jun 21, 2022 12:24 pm

mararcin wrote: Mon Jun 20, 2022 10:11 pm How long could organic material last on Mars today? Because of their size, I think they look like sticks. Am I alone in this?
They may look like sticks, but they are almost certainly not sticks, either organic or fossils thereof. What's the evidence for that? Mostly because they resemble similar structures (hoodoos) on earth and we have an adequate mechanism to explain how they could have formed.
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Re: APOD: Rock Fingers on Mars (2022 Jun 20)

Post by JohnD » Tue Jun 21, 2022 4:56 pm

They look like sticks? They are neither brown nor sticky!