APOD: Ireson Hill on Mars (2017 Jul 19)

[APOD Robot]

Ireson Hill on Mars

Explanation: What created this unusual hill on Mars? Its history has become a topic of research, but its shape and two-tone structure makes it one of the more unusual hills that the robotic Curiosity rover on Mars has rolled near. Dubbed Ireson Hill, the mound rises about 5 meters high and spans about 15 meters across. Ireson Hill is located on the Bagnold Dune field on the slope of Mount Sharp in Gale Crater on Mars. The featured 41-image panorama has been horizontally compressed to include the entire hill. The image was taken on February 2 and released last week. Because Mars is moving behind the Sun as seen from the Earth, NASA will soon stop sending commands to its Martian orbiters and rovers until about August 1.

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[Astronymus]

Probably some kind of volcanic vent or former way of mineralized water.

[heehaw]

"Horizontally compressed." Until I read that, I was a bit shocked!

[neufer]

<<A midden (also kitchen midden or shell heap; from early Scandinavian; Danish: mødding, Swedish regional: mödding) is an old dump for domestic waste which may consist of animal bone, human excrement, botanical material, mollusc shells, sherds, lithics (especially debitage), and other artifacts and ecofacts associated with past human occupation. The word is of Scandinavian via Middle English derivation, and is today used by archaeologists worldwide to describe any kind of feature containing waste products relating to day-to-day human life. They may be convenient, single-use pits created by nomadic groups or long-term, designated dumps used by sedentary communities that accumulate over several generations. These features, therefore, provide a useful resource for archaeologists who wish to study the diet and habits of past societies. Middens with damp, anaerobic conditions can even preserve organic remains in deposits as the debris of daily life are tossed on the pile. Each individual toss will contribute a different mix of materials depending upon the activity associated with that particular toss. During the course of deposition sedimentary material is deposited as well. Different mechanisms, from wind and water to animal digs, create a matrix which can also be analyzed to provide seasonal and climatic information. In some middens individual dumps of material can be discerned and analysed.>>

• • FINNEGANS WAKE by James Joyce
  What a mnice old mness it all mnakes!
  A middenhide hoard of objects! Olives, beets, kim-
  mells, dollies, alfrids, beatties, cormacks and daltons. Owlets' eegs
  (O stoop to please!) are here, creakish from age and all now
  quite epsilene, and oldwolldy wobblewers, haudworth a wipe o
  grass. Sss! See the snake wurrums everyside! Our durlbin is
  sworming in sneaks. They came to our island from triangular
  Toucheaterre beyond the wet prairie rared up in the midst of the
  cargon of prohibitive pomefructs but along landed Paddy Wip-
  pingham and the his garbagecans cotched the creeps of them
  pricker than our whosethere outofman could quick up her whats-
  thats. Somedivide and sumthelot but the tally turns round the
  same balifuson. Racketeers and bottloggers.

<<Having scratched it up from the midden heap, Biddy ‘the hen’ Doran reads the letter. She recognises a crudeness but fundamental honesty in what she takes to be ALP’s writing. The shock of Biddy’s encounter with literature confirms that whatever it is the ‘letter’ is more than simply a letter. This seems to bring on another of the Wake’s notorious ‘thunderwords’ (p.113.9 – 11). Biddy relays her understanding of the letter as she reads it to the other examiners, and us. She sees Anna Livia as a woman not out to impress or beguile with fancy language or allusion but intent on giving a plain account of things, ‘to tell the cock’s trootabout him’, ‘him’ being H.C. Earwicker (p.113.12.). ALP appears to accept her husband’s appetites and his tendency to live life to the full. She also recognises this as the old story of a larger than life man who found conventional relationships too constraining.>>

[Asterhole]

This small of a land feature is probably not caused directly by volcanic forces. Rather I see at least two types of structure here. The lower exhibits stratification which would suggest - billions of Earth years ago - water moving across this area which repeatedly deposited sediments which later solidified. On top there is sand / dust and chunks of basaltic rock, probably deposited by a combination of wind and distant volcanism. How it got to become this shape - no idea.

But that's just my take on it. I could be entirely off base.

Midden?

[bls0326]

I like the "uncompressed" version of the today's picture better.

[Chris Peterson]

I like the "uncompressed" version of the today's picture better.

You should always like the click-thru image of APODs better. The images displayed on the main page are almost always reduced resolution, sometimes distorted, and frequently lack embedded color profiles. If you don't regularly follow the main page image to the actual submission, you're usually missing something important.

[Keyman]

Yeahbut. If you do that it looks like a...hill.

[JohnD]

Curio has been inching up to Ireson since January!
See: http://redplanet.asu.edu/?s=ireson

Lots more views in B&W, but no theories of its formation/

John

[neufer]

Smials were the hobbit-holes tunelled into earth mounds and hills.

• "Smials. A word peculiar to hobbits (not Common Speech), meaning 'burrow'; leave unchanged. It is a form that the Old English word smygel 'burrow' might have had, if it had survived. The same element appears in Gollum's real name, Sméagol."
  ― Tolkien
  
  "In a hole in the ground there lived a Hobbit. Not a nasty, dirty, wet hole, filled with the ends of worms and oozy smell, nor yet a dry, bare, sandy hole with nothing in it to sit down on or to eat: it was a hobbit-hole and that means comfort."
  ― The Hobbit, "An Unexpected Party"

For generations the Hobbits, made diggings in the earth to live. By the later Third Age the poorest Hobbits still went on living in burrows of the most primitive kind with only one window or none. For the most well-to-do hobbits, smials were luxurious versions of those primitive diggings of old. Their tunnels had rounded walls and branched to other rooms. Smials included Bag End and the smials along Bagshot Row of Hobbiton, the Great Smials of Tuckborough and Brandy Hall. The latter two were large enough to have ample room for a hundred Hobbits.>>

[Zuben L. Genubi]

Are these shiny black fragmented rocks found in other rover images? Interesting that they are not found around the base of this feature. The deformation of the pink rock might suggest that this an upthrusting of some sort.

[BillBixby]

First impression on viewing the image was to reach for my 3D red and blues. Looks like a great image which will take some study and still leave unresolved questions.

[De58te]

Here's my layman's theory. At the base of the hill I see light brown colored rock, similar to the color of the horizon and atmosphere. These are more or less layered and even. I would think they are Mars bedrock. Then we see dark grey sand. Wind born of course. On top and scattered haphazardly are dark blue colored rock. They look like mining debris. Most likely they were violently thrown there in maybe a meteor impact. In the NASA panorama link they say that the darker rocks analyzed have more and more iron and alkali. Iron meteor? However the Ireson Hill is at the entrance to a mile long streak of dark blue Martian terrain. The dark rocks could be blasted from the darker terrain. https://mars.nasa.gov/multimedia/images ... h-sol-1598 .

[JohnD]

Meteoric iron would be nice. But landing at the usual speed for a meteor, with almost no atmosphere to slow it down would crater the bedrock and spread the meteor across the Marscape as vapour, condensing to dust. Is there a mechanism for a slow speed landing?l
John

[neufer]

One should note that:

The dark Ireson Hill is located on the dark Bagnold Dune field on the slope of Mount Sharp in Gale Crater on Mars.

More than likely Ireson Hill is made of the same dark material as the Bagnold Dune field.

More than likely they were all under water and/or under other material at one time.

[geoffrey.landis]

Really. This is not a feature on Mars.

[neufer]

Really. This is not a feature on Mars.

• Cross over Bar Harbor & follow the blueberries:

<<One of our fondest memories of Bar Harbor Campground is the hillside covered in blueberries overlooking Frenchman's Bay to the north. "Blueberry Barrens" are described by the State of Maine on their website, and I think this hillside fits that description.

May I digress about the rock? It's always there, just under foot, and it clearly plays a major part in how things grow here. I've never known quite what it was, but it's very different from the rest of the island, nothing like the famous pink granite of Cadillac Mountain. The geology map says it's the Bar Harbor Formation, which is composed of sandstones and siltstones that often show obvious bedding layers. I now see the bedrock maps says this is "Ireson Hill": "The rocks found along the shore at The Ovens and in the road-cuts along Route 3 at Ireson Hill on the northern side of the island also belong to the Bar Harbor Formation, but here the rock is flint-like and bedding is difficult or impossible to see. Some of these rocks are believed to be accumulations of ash that settled out of the atmosphere after a volcanic eruption." >>

[Chris Peterson]

Meteoric iron would be nice. But landing at the usual speed for a meteor, with almost no atmosphere to slow it down would crater the bedrock and spread the meteor across the Marscape as vapour, condensing to dust. Is there a mechanism for a slow speed landing?

Yeah. The atmosphere. The rovers have found many meteorites sitting on the surface. On Mars, meteoroids which survive burning up in the upper atmosphere fall with a terminal velocity on the order of five to ten times that on Earth, still below the speed of sound and too slow to cause cratering. (Recall that Martian landers typically use parachutes for part of their landing sequence.)

[neufer]

Meteoric iron would be nice. But landing at the usual speed for a meteor, with almost no atmosphere to slow it down would crater the bedrock and spread the meteor across the Marscape as vapour, condensing to dust. Is there a mechanism for a slow speed landing?

Yeah. The atmosphere. The rovers have found many meteorites sitting on the surface. On Mars, meteoroids which survive burning up in the upper atmosphere fall with a terminal velocity on the order of five to ten times that on Earth, still below the speed of sound and too slow to cause cratering. (Recall that Martian landers typically use parachutes for part of their landing sequence.)

Meteoric iron in the past could also have been slowed by:

• 1) a thicker atmosphere
  2) a crater lake and/or
  3) the sediment left by that lake.

http://asterisk.apod.com/viewtopic.php? ... 91#p273085

[Chris Peterson]

Meteoric iron would be nice. But landing at the usual speed for a meteor, with almost no atmosphere to slow it down would crater the bedrock and spread the meteor across the Marscape as vapour, condensing to dust. Is there a mechanism for a slow speed landing?

Yeah. The atmosphere. The rovers have found many meteorites sitting on the surface. On Mars, meteoroids which survive burning up in the upper atmosphere fall with a terminal velocity on the order of five to ten times that on Earth, still below the speed of sound and too slow to cause cratering. (Recall that Martian landers typically use parachutes for part of their landing sequence.)

Meteoric iron in the past could also have been slowed by:

• 1) a thicker atmosphere
  2) a crater lake and/or
  3) the sediment left by that lake.

Sure. But even under current conditions, the atmospheric density in Earth's atmosphere at the point where meteorites are typically in free fall (they have lost their initial velocity) corresponds to a height in the Martian atmosphere of about 10 km. The scale heights of the two atmospheres aren't radically different (11 km on Mars versus 8.5 km on Earth). Meteors and meteorites don't behave all that differently between the two.

[bystander]

Really. This is not a feature on Mars.

It's not vertically stretched, it's horizontally compressed.

[neufer]

Yeah. The atmosphere. The rovers have found many meteorites sitting on the surface. On Mars, meteoroids which survive burning up in the upper atmosphere fall with a terminal velocity on the order of five to ten times that on Earth, still below the speed of sound and too slow to cause cratering. (Recall that Martian landers typically use parachutes for part of their landing sequence.)

Meteoric iron in the past could also have been slowed by:

• 1) a thicker atmosphere
  2) a crater lake and/or
  3) the sediment left by that lake.

Sure. But even under current conditions, the atmospheric density in Earth's atmosphere at the point where meteorites [sic] are typically in free fall (they have lost their initial velocity) corresponds to a height in the Martian atmosphere of about 10 km.

That sort of depends on the size of the meteor.

[Chris Peterson]

Sure. But even under current conditions, the atmospheric density in Earth's atmosphere at the point where meteorites [sic] are typically in free fall (they have lost their initial velocity) corresponds to a height in the Martian atmosphere of about 10 km.

That sort of depends on the size of the meteor [sic].

Obviously. If the meteoroid is more than a few meters in diameter, it's possible for it to reach the ground before it loses all of its initial velocity, which means the collision could release much more energy- enough to melt some or all of the body and to produce a crater. But the important point here is that the production of meteorites on Mars is similar to that on Earth.

(BTW, the correct term for material which survives ablation and is in the process of cold fall is "meteorite". Even before it hits the ground.)

[Stephen Dale]

MIght it be an ancient meteor shock cone that has been eroded?

[neufer]

(BTW, the correct term for material which survives ablation and is in the process of cold fall is "meteorite". Even before it hits the ground.)

• Meteoroid => Meteor => Meteorite

<<A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the Earth's atmosphere and impact with the Earth's surface or that of another planet. When the object enters the atmosphere, various factors like friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate that energy. It then becomes a meteor and forms a fireball, also known as a shooting star or falling star; astronomers call the brightest examples "bolides." Meteorites that survive atmospheric entry and impact vary greatly in size. For geologists, a bolide is a meteorite large enough to create a crater.>>

<<A meteoroid is a small rocky or metallic body in outer space. Meteoroids are significantly smaller than asteroids, and range in size from small grains to 1 meter-wide objects. Objects smaller than this are classified as micrometeoroids or space dust. Most are fragments from comets or asteroids, whereas others are collision impact debris ejected from bodies such as the Moon or Mars.>>

<<Traditionally, small bodies orbiting the Sun were classified as comets, asteroids, or meteoroids, with anything smaller than 10 meters across being called a meteoroid (such as in Beech and Steel's 1995 paper). The term "asteroid", from the Greek word for "star-like", never had a formal definition, with the broader term minor planet being preferred by the International Astronomical Union. However, following the discovery of asteroids below 10 meters in size, Rubin and Grossman in a 2010 paper revised the previous definition of meteoroid to objects between 10 µm and 1 meter in size in order to maintain the distinction between asteroids and meteoroids.>>