APOD: Unusual Rocks near Pahrump Hills on Mars (2014 Sep 29)

[APOD Robot]

Unusual Rocks near Pahrump Hills on Mars

Explanation: How did these Martian rocks form? As the robotic Curiosity rover has approached Pahrump Hills on Mars, it has seen an interesting and textured landscape dotted by some unusual rocks. The featured image shows a curiously round rock spanning about two centimeters across. Seemingly a larger version of numerous spherules dubbed blueberries found by the Opportunity rover on Mars in 2004, what caused this roundness remains unknown. Possibilities include frequent tumbling in flowing water, sprayed molten rock in a volcanic eruption, or a concretion mechanism. The inset image, taken a few days later, shows another small but unusually shaped rock structure. As Curiosity rolls around and up Mount Sharp, different layers of the landscape will be imaged and studied to better understand the ancient history of the region and to investigate whether Mars could once have harbored life.

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[Mactavish]

Me thinks I would take a mulligan.

[BDanielMayfield]

Me thinks I would take a mulligan.

I had a similar thought. That was one really errant tee shot.

[Sebassien]

For me, the most unusual feature was that of Sol173, with some sort of twin hollow shells, eroded from below:


This is what I have in mind, a combination of pictures explains it best:

[RichardEgel]

Getting hot, approaching the target, I think.
What I was reminded of first is the following.
Looking closely at the original image, the peculiar 'Mulligan' pretender is placed in a conspicuous bowl -- not too obvious at first glance, but clearly recognizable. This is quite similar to a 'moulin pothole', which commonly is formed undeneath a glacier underneath a vertical shaft of rapidly streaming melt water. So transfer this kind of fluid dynamics to a wind-blown flat of rocky terrain. This brought me to the likewise familiar phenomenon of 'rocking stones' on Earth, which commonly are much larger than the Marsian mulligan in question.
A fortuitous combination of both sets of boundary conditions is probably the best bet for the formation this complementary pair of ball in a bowl. The grinding impact of wind-blown sand will act on both the semi-stable stone on top and the slightly concave substrate surface underneath. The strongest winds will be able to shift the stone back and forth a little -- rather occasionally at first, but more and more regularly as time goes by and both the bowl and the tumbling ball are being smoothened to perfect roundness as the most symmetrical shape.

[Astronymus]

Cannonball from the last battle on Mars.

[PhiVer]

I think sombody lost his marbles

[madtom1999]

I've seen lava bombs that are pretty much spherical so I'm guessing the same thing could happen with ejecta from meteorite impacts - a lump of molten material is thrown high enough to allow it to cool as a solid sphere before returning through the thin atmosphere and landing somewhere soft enough not to break it.

[Alex-the-great]

Cute and funny.

The ball fits so nicely inside its cup-sized little bed.

[starsurfer]

Me thinks I would take a mulligan.

Mulligan is one of my favourite names!

Also haven't similar glass spheres been found on the Moon?

[BDanielMayfield]

Getting hot, approaching the target, I think.
What I was reminded of first is the following.
Looking closely at the original image, the peculiar 'Mulligan' pretender is placed in a conspicuous bowl -- not too obvious at first glance, but clearly recognizable. This is quite similar to a 'moulin pothole', which commonly is formed undeneath a glacier underneath a vertical shaft of rapidly streaming melt water. So transfer this kind of fluid dynamics to a wind-blown flat of rocky terrain. This brought me to the likewise familiar phenomenon of 'rocking stones' on Earth, which commonly are much larger than the Marsian mulligan in question.
A fortuitous combination of both sets of boundary conditions is probably the best bet for the formation this complementary pair of ball in a bowl. The grinding impact of wind-blown sand will act on both the semi-stable stone on top and the slightly concave substrate surface underneath. The strongest winds will be able to shift the stone back and forth a little -- rather occasionally at first, but more and more regularly as time goes by and both the bowl and the tumbling ball are being smoothened to perfect roundness as the most symmetrical shape.

Very nice first post Richard. I think you've nailed it. Score an assist for Sebassien too though for his excellent submission.

[BDanielMayfield]

And as for the inset image, I think it is a ventifact, which is also a wind erosional feature. These are the pointy rocks that have been chewing up Curiosity's wheels.

[Ron-Astro Pharmacist]

I was wondering where that drive ended up? Guess it was out-of-bounds. Have to stop swinging so hard. Re-entry is tough on golf balls – even on Mars.

[Helianthus19]

These are obviously food balls made by mineral-based dung beetles. (See Wikipedia on dung beetles.) The question is, what (mineral-based?) life form produced the dung?

[Sebassien]

What's on top of the ventifact of Sol173 is still unknow per se. Both parts are hollow and seem identical, like a shell. But if that was a shell, there would be of course many more occurences elsewhere.

[Guest]

Could the amoeba looking things could be a consequence of lightning strikes melting sand?

[ta152h0]

some brits on top of the hill rolling down cheeseballs

[BMAONE23]

These are obviously food balls made by mineral-based dung beetles. (See Wikipedia on dung beetles.) The question is, what (mineral-based?) life form produced the dung?

Lets ask the Horta Culturist

The Horta was a silicon-based lifeform from Janus VI. It was composed of a material similar to fibrous asbestos.
Horta physiology was very different from the carbon-based norm more commonly found in the galaxy. Horta were difficult to detect with tricorders, and were invulnerable to type 1 phasers, though they could be injured with an adjusted type 2 phaser. They fed on rock, and thus they were nourished just by tunneling

Click to view full size image

[Boomer12k]

Mulligan....one of OBAMA'S golf shots....OK...my bad...

The insert on the left....

Ms. Piggy Squished KERMIT.....

But what really gets me is the rock just above and to the left of the Round Rock....

There is an etching on the inside....for the life of me...it is a FISH, or SHARK...it has a head, body, fin, and tail, a Whale maybe,....could it just be ACCIDENT?????

:---[===] *

[chuckster]

Something you don't hear much discussion of is the way the roughly half-gee gravity on Mars affects Earth-based human intuitions about processes there. Everyone seems caught up in the Moab-type desert terrain and water effect analogies. I once thought that standing on the summit of Olympus Mons would be analogous to standing in open space, since my "intuition" told me that Mars' thin atmosphere would all be thousands of feet lower. I was corrected with the explanation that the low Martian gravity doesn't hug the atmosphere as closely as on Earth, and is therefore more "puffy", and more prevalent at higher elevations.
So, how about tumbling Mulligans ? What part does gravity play in their formation, or resistance to their formation etc etc ?

[ronanov]

Could the amoeba looking things could be a consequence of lightning strikes melting sand?

I agree, very likely a fulgurite.

[Tszabeau]

Here's a pic of some objects I found in North Texas. The two rocks on the left are both from Stony Creek and the one on the right I found in my backyard. The one on the left looks, to my untrained eye, to be an example of the "rocking" type of erosion. It has a tiered "nest" and an "egg", so to speak, that fits neatly into the wobbled-out "nest".
I imagine the one in the middle could have been made similarly, to the point it's egg hatched. The one on the right is not, actually, a rock but could be fused bearings or something mundane. It is metallic and harder than lead. The way it's fused reminded me of the "thigh bone" that was spotted on Mars, a while back.
https://www.dropbox.com/s/hoyqcp71uq76p ... s.jpg?dl=0

[moonshine-r]

An alice-in-wonderland analysis must be applied to image. The image in question may be anything from flood water sculpture to rodent poop. If object is indeed excrement of some kind, then a conclusion may be attempted: that martian creatures thrive on non gmo food stuff.
Since the presence of biological activity on Mars was established a long time ago, it is useless to debate the 'are we alone'
issue in this context. Even so, it would be proper to assert that the ball-like object appears to be more like stony material rather than metabolic waste.
The Spirit and Opportunity rovers proved that the general color of Martian rock is bluish grey. This is significant in terms of geochemistry. Martian rock turns red on exposure to oxygen due to the presence of iron in the rock. This should give an indication of the chemical composition of Martian rock and the amount of oxygen in the atmosphere. Other factors such as high intensity of cosmic particles in the sparse Martian atmosphere may influence the manner in which blue martian rock turns to red.
Moon rock also must be compared to the general composition of terrestrial planets analyzed thus far. Not that it would lead to any new discoveries. But, sending space probes to Mars in search of space rock seems more honorable than searching for martian dung.
A few weeks from now a comet is expected to collide with Mars. Approximations of the comet size range from 700 meters to over 5 kilometers. It would be interesting to see how comet particles behave in the Martian atmosphere.

[chuckster]

Something you don't hear much discussion of is the way the roughly half-gee gravity on Mars affects Earth-based human intuitions about processes there. Everyone seems caught up in the Moab-type desert terrain and water effect analogies. I once thought that standing on the summit of Olympus Mons would be analogous to standing in open space, since my "intuition" told me that Mars' thin atmosphere would all be thousands of feet lower. I was corrected with the explanation that the low Martian gravity doesn't hug the atmosphere as closely as on Earth, and is therefore more "puffy", and more prevalent at higher elevations.
So, how about tumbling Mulligans ? What part does gravity play in their formation, or resistance to their formation etc etc ?

Good question, Chuckster ! Next question . . . ?

[geckzilla]

I would venture to say that if no one answers your question, we either don't know the answer or aren't willing to speculate.