APOD: Perseverance 360: Unusual Rocks and... (2021 Mar 09)

[APOD Robot]

Perseverance 360: Unusual Rocks and the Search for Life on Mars

Explanation: Is that a fossil?  Looking through recent images of Mars taken by the new Perseverance rover may seem a bit like treasure hunting, with the possibility of fame coming to the first person to correctly identify a petrified bone, a rock imprinted by an ancient plant, or any clear indication that life once existed on Mars.  Unfortunately, even though it is possible that something as spectacular as a skeleton could be identified, most exobiologists think it much more likely that biochemical remnants of ancient single-celled microbes could be found with Perseverance's chemical analyzers.  A key reason is that multicellular organisms may take a greater amount of oxygen to evolve than has ever been present on Mars. That said, nobody's sure, so please feel free to digitally magnify any Perseverance image that interests you -- including the featured 360-degree zoomable image of the rocks and ridges surrounding Perseverance's landing location in Jezero Crater. And even though NASA-affiliated scientists are themselves studying Perseverance's images, if you see anything really unusual, please post it to popular social media. If your sighting turns out to be particularly intriguing, scientifically, it is likely that NASA will hear about it.

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[alter-ego]

I'm intrigued by a few, randomly placed, very flat, table-top like rocks. It looks like they were shaved. Reminded me of newly cut tree stumps. If there were large areas or patches of them it would be less interesting to me. Of all the rocks there's a half dozen or so that a oddly stand out.

[WWW]

Possible sign of past life. Seems like there might be a few dead bugs stuck on the camera lens. (Sure hope they filled the washer reservoir before they left.) At higher magnification you can see at least two dark smudges on every stitched frame. One near right center of each frame, (looks like a dagger in the sand), another smaller smudge at the far top left.

Of course it’s possible they’re just specks of dust on the lens, or could they be tiny extremophile dust mites crawling over the lens?

[WWW]

The medium size darker stones sitting atop of the lighter color flat stones almost seems like it could be from glacial action, (the dark stones would have come from a different area and dragged there by an ice flow). When the glacier melts the stones settle out and seem very out of place compared to the original surface stone. The actions of an ancient glacier can mimic many features of an ancient river flow. Even the small hills in the nearer background look to be made of small stones and gravel rather than from fine sand. Large deposits of small stones and gravel might be similar to glacial mounds on Earth known as terminal moraines, these form at the edges and ends of a melting glacier. https://en.wikipedia.org/wiki/Terminal_moraine . One sure sign of glacial action would be to view the surfaces of the flat surface stones up close and look for striation scratches. https://en.wikipedia.org/wiki/Glacial_striation

[orin stepanek]

Thanks for the 360 panorama! Neat photo of Percy's surroundings!

[Tszabeau]

Do sand traps count as a sign of life?

[johnnydeep]

Sorry about the double post, the page jammed up on me for a while.

You are able to delete (and edit) your own posts. I've have to do both things many times myself!

[Chris Peterson]

Sorry about the double post, the page jammed up on me for a while.

You are able to delete (and edit) your own posts. I've have to do both things many times myself!

Only if you create an account. WWW is posting as a guest, so there is no such ability.

[johnnydeep]

I'm intrigued by a few, randomly placed, very flat, table-top like rocks. It looks like they were shaved. Reminded me of newly cut tree stumps. If there were large areas or patches of them it would be less interesting to me. Of all the rocks there's a half dozen or so that a oddly stand out.

Mind pointing a few out with screen captures and arrows? I don't see anything particularly noteworthy myself...yet. Just a random assemblage of rocks of all shapes and sizes stuck at random orientations in the ground. Yeah, a few have flatish tops, but nothing special IMO.

EDIT: I do see some nicely rounded rocks that look like clear signs of erosion by water though!

Eroded Rocks in Jezero Crater?

[johnnydeep]

Sorry about the double post, the page jammed up on me for a while.

You are able to delete (and edit) your own posts. I've have to do both things many times myself!

Only if you create an account. WWW is posting as a guest, so there is no such ability.

Ah. So if WWW creates an account now can he then alter prior posts posted by him/her as a guest?

[Chris Peterson]

You are able to delete (and edit) your own posts. I've have to do both things many times myself!

Only if you create an account. WWW is posting as a guest, so there is no such ability.

Ah. So if WWW creates an account now can he then alter prior posts posted by him/her as a guest?

No, I don't think so. Those posts have no identifiable owner. I imagine they are only modifiable by somebody with administrative privileges.

[Fred the Cat]

Fantastic image from Mars with so much detail I can see why the ask for input. The large boulders seem like both a hazard for landing and a source for discussion about their “roundness” – water or wind erosion?

What came to mind regarding the search for previous life robotically or from humans was, if so much was done to decontaminate the rover, how could we ever not bring unwanted life to Mars exploring in person?

[Chris Peterson]

Fantastic image from Mars with so much detail I can see why the ask for input. The large boulders seem like both a hazard for landing and a source for discussion about their “roundness” – water or wind erosion?

What came to mind regarding the search for previous life robotically or from humans was, if so much was done to decontaminate the rover, how could we ever not bring unwanted life to Mars exploring in person? :?

It is unlikely that anything we would bring from Earth could survive on Mars for long. So mainly it's about avoiding the immediate contamination of material that is being studied, which is quite feasible. Indeed, a good deal of science right here on Earth is conducted under those requirements.

[De58te]

What I find amazing besides the picture is the amazing space technology. Just think this rover landing happened some 50 or 60 million miles away. I can see the area is littered by some car sized boulders particularly along the ridge some 100 yards away (I don't know what the scale is.) especially on the right and left sides of the panorama. And yet when you look at the picture of the landing site where the rover moved some 150 degrees and backed up, you notice that the ground is flat with only pebble size rocks. What the perfect choice in picking a landing site! Imagine what would have happened if the rover landed a few hundred yards away on top of one of those boulders? Would the rover have toppled over? Even if it remained upright would it been able to drive off one of the large pointed rocks?

[Chris Peterson]

What I find amazing besides the picture is the amazing space technology. Just think this rover landing happened some 50 or 60 million miles away. I can see the area is littered by some car sized boulders particularly along the ridge some 100 yards away (I don't know what the scale is.) especially on the right and left sides of the panorama. And yet when you look at the picture of the landing site where the rover moved some 150 degrees and backed up, you notice that the ground is flat with only pebble size rocks. What the perfect choice in picking a landing site! Imagine what would have happened if the rover landed a few hundred yards away on top of one of those boulders? Would the rover have toppled over? Even if it remained upright would it been able to drive off one of the large pointed rocks?

While the technology is fascinating, and the consequences of failure large, we should understand that the task here was quite ordinary by today's standards of computer smarts. The lander didn't even have to choose the spot, just maintain course within a previously defined visual field. This is pretty much what every self-driving car does, what millions of pieces of industrial automation do.

[sp0ck]

I'm intrigued by a few, randomly placed, very flat, table-top like rocks. It looks like they were shaved. Reminded me of newly cut tree stumps. If there were large areas or patches of them it would be less interesting to me. Of all the rocks there's a half dozen or so that a oddly stand out.

Mind pointing a few out with screen captures and arrows? I don't see anything particularly noteworthy myself...yet. Just a random assemblage of rocks of all shapes and sizes stuck at random orientations in the ground. Yeah, a few have flatish tops, but nothing special IMO.

EDIT: I do see some nicely rounded rocks that look like clear signs of erosion by water though!


Erroded Rock in Jezero Crater.JPG

I was noticing a lot of vaguely ovoid rocks toward the left end of the panorama. I wouldn't get to close...

[Avalon]

Is there a way to label the panorama with explanations of known geographical features? I can see portions of the delta formation in the distance, even with some strata appearing in the cliff faces, but some of the sharp peaks more toward the center of the crater appear to be volcanic? Is ancient volcanic activity even possible in the crater floor?

[Round rock denizen]

I see a Jawa truck running after R2D2 and C3PO.

I also have to remind myself that, grandiose scenery and warm rosy tones aside, it's c-c-c-cold and in a near-vacuum. You gotta be a robot to really enjoy it (until the dust gets you, that is).

[Sam Waldon]

As I reviewed the 360 image, I was struck by the large number of rocks that appeared triangular, pyramidal, or conical. They almost looked like plant sprouts trying to poke out of the ground on a spring day! What's even more intriguing is that many of these rocks are located right next to a perfectly rounded rock. With all the sand, which blows often, it would seem erosion would affect all rocks similarly. Why are some of these rocks so acutely angular?

[alter-ego]

I'm intrigued by a few, randomly placed, very flat, table-top like rocks. It looks like they were shaved. Reminded me of newly cut tree stumps. If there were large areas or patches of them it would be less interesting to me. Of all the rocks there's a half dozen or so that a oddly stand out.

Mind pointing a few out with screen captures and arrows? I don't see anything particularly noteworthy myself...yet. Just a random assemblage of rocks of all shapes and sizes stuck at random orientations in the ground. Yeah, a few have flatish tops, but nothing special IMO.

EDIT: I do see some nicely rounded rocks that look like clear signs of erosion by water though!


Erroded Rock in Jezero Crater.JPG

Yup, a lot of randomly oriented rocks, round and angular. I think the lighting and what appears to be dust probably contribute to the illusion a particularly smooth, flat appearance. The ones that caught my eye all had the light-colored top and elevated surface. The first one below I found first, and is the most table-like. Looks like maybe a couple cycles of erosion. Probably a of these are laying around, and maybe many level with the ground surface that don't stand out.

FlatRock1.jpg (7.29 KiB) Viewed 4720 times

FlatRock3.jpg (5.89 KiB) Viewed 4720 times

FlatRock2.jpg (4.87 KiB) Viewed 4720 times

[johnnydeep]

I'm intrigued by a few, randomly placed, very flat, table-top like rocks. It looks like they were shaved. Reminded me of newly cut tree stumps. If there were large areas or patches of them it would be less interesting to me. Of all the rocks there's a half dozen or so that a oddly stand out.

Mind pointing a few out with screen captures and arrows? I don't see anything particularly noteworthy myself...yet. Just a random assemblage of rocks of all shapes and sizes stuck at random orientations in the ground. Yeah, a few have flatish tops, but nothing special IMO.

EDIT: I do see some nicely rounded rocks that look like clear signs of erosion by water though!


Erroded Rock in Jezero Crater.JPG

Yup, a lot of randomly oriented rocks, round and angular. I think the lighting and what appears to be dust probably contribute to the illusion a particularly smooth, flat appearance. The ones that caught my eye all had the light-colored top and elevated surface. The first one below I found first, and is the most table-like. Looks like maybe a couple cycles of erosion. Probably a of these are laying around, and maybe many level with the ground surface that don't stand out.

FlatRock1.jpg

FlatRock3.jpg

FlatRock2.jpg

Thanks! I see what you mean. That first one in particular is strikingly flat (or at least appears to be) and the light colored tops of all of them are also interesting.

[Sam Waldon]

Refer to photo Flat Rock 3 in alter-ego's thread comment. It illustrates the triangular shape I mentioned. I can understand flat or rounded shapes resulting from sedimentation or erosion, but why the sharp angular shapes among them?

[Chris Peterson]

Refer to photo Flat Rock 3 in alter-ego's thread comment. It illustrates the triangular shape I mentioned. I can understand flat or rounded shapes resulting from sedimentation or erosion, but why the sharp angular shapes among them?

Angular rock shapes, facets, and pits are all indications that we're looking at ventifacts, rocks ablated by blowing sand particles.

[johnnydeep]

Refer to photo Flat Rock 3 in alter-ego's thread comment. It illustrates the triangular shape I mentioned. I can understand flat or rounded shapes resulting from sedimentation or erosion, but why the sharp angular shapes among them?

Angular rock shapes, facets, and pits are all indications that we're looking at ventifacts, rocks ablated by blowing sand particles.

Cool! I wouldn't have thought it possible for wind to form a pyramidal shape, but it apparently happens. From the link to Dreikanter - https://en.wikipedia.org/wiki/Dreikanter:

A Dreikanter is a type of ventifact that typically forms in desert or periglacial environments due to the abrasive action of blowing sand.[1][2]

Dreikanters exhibit a characteristic pyramidal shape with three wind-abrased facets. The word Dreikanter is German for "three-edged."[3]

Similarly, a zweikanter ("two-edged") has two wind facets, an einkanter ("one-edged"), has only one wind facet. [4]

Most places on the planet have several weathering processes acting at the same time, so finding good examples of Dreikanters is often difficult. Antarctica is a good location for finding such ventifacts since wind is usually the only active weathering agent. Many specimens in the Northeastern United States were formed during the Pleistocene era when the absence of vegetation made for little cover from wind-blown sediment.[5]
..
Formation

In areas where there is a prevailing wind, sand and debris cause a rock face to become flattened and polished. This changes the mass distribution of the rock, and may cause it to turn another surface toward the wind. If this process continues undisturbed, the resulting rock will have three distinct flattened and polished faces.[7] Dreikanters generally form in dry, arid environments from hard rocks.[7]

[Sam Waldon]

Thank you, Chris and Johnny. My geology understanding is weak, but still wondering why there are these sharply angular rocks right next to very smooth, rounded ones. If they've both endured eons of sand blasting, and if they are apparently from the same rock formation, wouldn't they erode similarly? Are they ejecta from relatively recent meteorite impacts?