Scientists directly measure thermal conductivity of iron at planetary core conditions for the first time
The earth’s magnetic field has been existing for at least 3.4 billion years thanks to the low heat conduction capability of iron in the planet’s core. This is the result of the first direct measurement of the thermal conductivity of iron at pressures and temperatures corresponding to planetary core conditions. DESY scientist Zuzana Konôpková and her colleagues present their study in the scientific journal Nature. The results could resolve a recent debate about the so-called geodynamo paradox.
The geodynamo generating the earth’s magnetic field is fed on convection in the iron-rich outer core of our planet that stirs the molten, electrically conducting material like boiling water in a pot. Combined with the rotation of the earth, a dynamo effect sets in, giving rise to the geomagnetic field. “The magnetic field shields us from harmful high-energy particles from space, the so-called cosmic radiation, and its existence is one of the things that make our planet habitable,” explains Konôpková.
The strength of the convection in the outer core depends on the heat transferred from the core to the earth’s mantle and on the thermal conductivity of iron in the outer core. If a lot of heat is transferred via conduction, there is not much energy left to drive convection – and with it the earths’s dynamo. Low thermal conductivity implies stronger convection, making the geodynamo more likely to operate. “We measured the thermal conductivity of iron because we wanted to know what the energy budget of the core is to drive the dynamo,” says Konôpková. “Generation and maintenance of our planet’s magnetic field strongly depend on the thermal dynamics of the core.”
Measurements of thermal conductivity at relevant conditions proved to be difficult in the past. Recent theoretical calculations postulated a quite high thermal conductivity of up to 150 Watts per meter per Kelvin (150 W/m/K) of iron in the earth’s core. Such a high thermal conductivity would reduce the chances of the geodynamo starting up.
According to numerical models, a high thermal conductivity would have allowed the geodynamo effect to be supported only rather recently in the earth’s history, about one billion years ago or so. However, the existence of the geomagnetic field can be traced back at least 3.4 billion years. This geodynamo paradox has puzzled scientists. “There’s been a fierce debate among geophysicists because with such a large thermal conductivity, it becomes hard to explain the history of the geomagnetic field which is recorded in ancient rocks”, says Konôpková.
The physicists used a specially designed pressure cell that allows to compress samples between two diamond anvils and to heat them simultaneously with infrared lasers, shining right through the diamonds. Konôpková teamed up with Stewart McWilliams and Natalia Gómez-Pérez from the University of Edinburgh and Alexander Goncharov from the Carnegie Institution in Washington DC to measure the thermal conductivity of iron at high pressure and high temperature conditions in Goncharov’s lab.
“We compressed a thin foil of iron in the diamond anvil cell to up to 130 Giga-Pascals, which is more than a million times the atmospheric pressure and corresponds to approximately the pressure at the earth’s core-mantle boundary,” explains Konôpková. “Simultaneously we heated up the foil to up to 2700 degrees Celsius with two continuous infrared laser beams, shining through the diamonds. Finally, we used a third laser to send a low power pulse to one side of the foil to create a thermal perturbation and measured the temperature evolution from both sides of the foil with an optical streak camera.” This way the scientists could watch the heat pulse travelling through the iron.
These measurements were conducted at several pressures and temperatures to cover different conditions of planetary interiors and to obtain a systematic investigation of the thermal conductivity as a function of pressure and temperature. “Our results strongly contradict the theoretical calculations,” reports Konôpková. “We found very low values of thermal conductivity, about 18 to 44 Watts per meter per Kelvin, which can resolve the paradox and make the geodynamo operable since the early ages of the earth.”
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Next, the physicists will use it to forge a sword so powerful, it will split the earth.
… you know, so they can measure the core itself. ^¿^
That illustration is pure crap with the word physics on the end of it, and that’s how the biggest scientific fools that make a mountain out of a mole hill we see so much of lately are peddling their wares.
The important point is that the Earth is a huge spinning magnet. Instead of the foolish fantasies about solar panels in orbit we saw in another article, all we need to do is slap a big induction coil around the Earth and we’ll have plenty of electricity. Easy peasy lemon squeezy.
The tricky bit is still that of getting the electricity down to us. Who will be in control of the microwave beam? We know the British could be trusted to handle it responsibly (you ask them if you don’t believe me) but the French would never accept that. I would suggest taking a cue from “The Mouse that Roared” and put it in the hands of a coalition of tiny countries. Monaco, Andorra, St. Kitts and Nevis, Malta, etc. (But not Liechtenstein. Liechtenstein is, technically, still at war with Prussia, and the Prussians already have enough sleepless nights over that.)
The actual control centre could be in the San Marino Science Institute. Anyone who wanted to participate would have to learn Esperanto.
Why Earth’s Inner and Outer Cores Rotate in Opposite Directions
By Laura Poppick,
September 19, 2013
http://www.livescience.com/39780-magnetic-field-pushes-earth-core.html
The Earth’s magnetic field controls the direction and speed at which Earth’s inner and outer cores spin, even though they move in opposite directions, new research suggests.
Scientists have long suspected that Earth’s magnetic field — which protects life from harmful space radiation — drifts in a slightly westerly direction. That theory was established in the 1690s, when geophysicist Edmund Halley (the same Halley who spotted the eponymous comet) sailed aboard a research vessel through the South Atlantic Ocean and collected enough compass readings to identify this shift.
By the mid-20th century, geologists had gathered further evidence for this drift and had determined that the westerly rotation of the magnetic field exerts a force on the liquid outer core— composed of a molten mix of iron and nickel — that causes it to rotate in a westerly direction. Decades later, geophysicists used deep seismic data to determine that the inner core — a solid iron-nickel alloy that is about the size of the moon — rotates in an easterly direction at a greater speed than the rotation of the Earth itself.
But, until now, scientists have regarded these rotations within the two layers of the core as separate, with no relation to each other.
Now, researchers at the University of Leeds in England have found a common link between the two rotations by creating a computer model that shows how the rotation of the Earth’s magnetic field can both pull the liquid outer core in a westerly direction while also exerting an opposite force on the inner core that causes an easterly rotation.
“Previously, there have been these two independent observations, and there has not been a link between them,” study co-author Philip Livermore, of the University of Leeds, told LiveScience’s OurAmazingPlanet. “We argue that the magnetic field itself is pushing on the outer core, and there is an equal and opposite push on the inner core.”
The Earth’s magnetic field — created by the convection of hot liquid metal within the outer core — undergoes slight fluctuations roughly every decade. The inner core’s rotation rate has also been shown to fluctuate on a similar timescale. These new results help explain why these two phenomena occur on the same timescale, since one has now been shown to affect the other, the researchers say……..
It should probably be clarified that “opposite directions” are relative to the surface of the planet. Not everyone thinks in those terms.
Now who woulda thunk there was an “equatorial jet,” down under dar. One of your favorite authors in the list below, Vuks.
http://www.pnas.org/content/110/40/15914/F3.medium.gif
“”Analysis of secular variation (3) shows there is rapid change within a narrow equatorial belt (latitude −5° to +10°), suggesting that these changes may be caused by instabilities on an equatorial jet.””
Electromagnetically driven westward drift and inner-core superrotation in Earth’s core
Philip W. Livermorea,1, Rainer Hollerbachb,c, and Andrew Jacksonc
http://www.pnas.org/content/110/40/15914.full
Abstract
A 3D numerical model of the earth’s core with a viscosity two orders of magnitude lower than the state of the art suggests a link between the observed westward drift of the magnetic field and superrotation of the inner core. In our model, the axial electromagnetic torque has a dominant influence only at the surface and in the deepest reaches of the core, where it respectively drives a broad westward flow rising to an axisymmetric equatorial jet and imparts an eastward-directed torque on the solid inner core. Subtle changes in the structure of the internal magnetic field may alter not just the magnitude but the direction of these torques. This not only suggests that the quasi-oscillatory nature of inner-core superrotation [Tkalčić H, Young M, Bodin T, Ngo S, Sambridge M (2013) The shuffling rotation of the earth’s inner core revealed by earthquake doublets. Nat Geosci 6:497–502.] may be driven by decadal changes in the magnetic field, but further that historical periods in which the field exhibited eastward drift were contemporaneous with a westward inner-core rotation. The model further indicates a strong internal shear layer on the tangent cylinder that may be a source of torsional waves inside the core.
Maybe if I read a bit further, I might find a strong equatorial jet.
“”” Because magnetic fields in general quench shearing motions, such a minimum is consistent with the existence of a strong equatorial jet.”””
I learn something new on this website every day. Thanks, Carla.
I’m getting dizzy now … all this rotation, rotation, rotation
https://youtu.be/o2DLMVxg02Q
a theory (150 Watts per meter per Kelvin) that is in conflict with the reality of 3.4 billion years is not a theory anymore … it was a bad guess that should never have been calculated …
Lab tests of “magnetic molten core material” have been years in the making,, on man made calculator paper receipts and spinning aluminum hard drives… lol
http://www.universetoday.com/30538/was-mars-magnetic-field-blasted-away/
KLohrn June 2, 2016 at 10:59 pm
http://www.universetoday.com/30538/was-mars-magnetic-field-blasted-away/
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Haven’t checked your link yet..
But am wondering what did happen to Mar’s magnetic field. If something like our Moon gave it a nudge, it’s core processes would have been greatly disturbed.
Also, wondering if one of the craters on Mars, is proportionally consistent with our Moon’s size???
When it comes down to it… the Universe, Galaxy, heliosphere is like one big pool table. Balls flying all over the place.
KLohrn June 2, 2016 at 10:59 pm
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Mar’s has gotten a Major hit to its north polar region.
From wiki “”””North Polar Basin by far the largest impact crater in the Solar System””””
https://en.wikipedia.org/wiki/North_Polar_Basin_(Mars)
“The North Polar Basin, or Borealis basin, is a large basin in the northern hemisphere of Mars that covers 40% of the planet. Chryse Planitia, the landing site of the Viking 1 lander, is a bay that opens into this basin.
One possible explanation for the basin’s low, flat and relatively crater-free topography is that the basin was formed by a single large impact. Two simulations of a possible impact sketched a profile for the collision: low velocity—6 to 10 km (3.7 to 6.2 mi) per second—oblique angle and a diameter of 1,600–2,700 km (990–1,680 mi).[1][2] Topographical data from Mars Global Surveyor are consistent with the models and also suggest that the elliptical crater has axes of length 10,600 km (6,600 mi) and 8,500 km (5,300 mi), centered on 67°N 208°E, though this has been partially obscured by later volcanic eruptions that created the Tharsis bulge along its rim. There is evidence for a secondary rim as well.[3][4]”
“””This would make the North Polar Basin by far the largest impact crater in the Solar System, approximately four times the diameter of the next largest craters: Utopia Planitia, which is imbedded inside the North Polar Basin, the South Pole–Aitken basin on the Moon, and Hellas Planitia on Mars’s southern hemisphere.[5]”””
Geeez Mars northern basin diameter and our Moon’s Aitken Basin diameter are proportionately similar.
Mars– diameter of 1,600–2,700 km (990–1,680 mi) from above wiki
Moon–The South Pole–Aitken basin is a huge impact crater on the far side of the Moon.
Roughly 2,500 kilometres “”(1,600 mi) in diameter”” and 13 kilometres (8.1 mi) deep,
it is one of the largest known impact craters in the Solar System.
https://en.wikipedia.org/wiki/South_Pole%E2%80%93Aitken_basin
Mars has a huge Basin at its north pole. Our Moon has a huge Basin at its south pole. Both basins are roughly 1600 miles in diameter. The direction the moon was coming from and the strike angle could be calculated. But not by me. lol hmm well some…
Lots of conjecture on the nature of something as mysterious as the the global internal.composition. What we have is a model which basically says “the earth is a molten ball covered with a thin skin of solidified magma and rock”. What if this whole model is wrong? The researchers assume it to be true and base their experimental design upon it.
Why would scientists think that the earth is molten to the core? Because they see molten rock spewing from below? My model, and it is as good as any UNPROVEN model, is that the tectonic plates absorb electromagnetic radiation. The net charge repels the other plates and keeps them apart. At places of close contact (of the tectonic plates) and due to uneven discharge of the adjoining plates, the charge differentials melt the rock (like an arc welder). Volcanoes are due to these electrical potentials. They are equivalent to sunspots. The earth spins because as the charge builds up on one side it is repelled away from the sun (electromagnetic energy source). Discharge is through the poles.
There…a fully defensible BUT different model of planetary composition and behavior. Pure conjecture on my part, of course, but remember we are all gathered here at this website because of scientific computer models of somewhat dubious repute.
I think this is a more than reasonable theory as compared to
the “molten iron dynamo”. There is so much discussed here
on this subject that I am going to spend quite some time
reading the posts and pondering. Fascinating stuff!
Are you suggesting our Moon was a celestial queue ball that knocked Mars’ molten gyro offline, Carla?
Or it were some born out of Mars?
Here is a wild one: There is a confirmed level of Xenon 129 on Mars.
This is an Isotope that can only be produced by a nuclear weapon detonation.
Maybe those huge craters are not “impact” craters, but war shots?
What I find wondering is the Venusian molten surface and its opposing rotation.
http://www.mnn.com/earth-matters/space/stories/scientists-baffled-to-discover-that-venus-spin-is-slowing-down-0
Anyway, I wouldn’t say Mars or Venus are incapable, they just aren’t as attractive.
http://www.astrobio.net/topic/solar-system/venus/a-magnetic-surprise-from-venus/
KLohrn June 3, 2016 at 12:58 pm
Are you suggesting our Moon was a celestial queue ball that knocked Mars’ molten gyro offline, Carla?
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Yes
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KLohrn June 3, 2016 at 1:37 pm
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You shouldn’t show me things like that.
Scared the bajeebahs out of me. SIX and HALF minutes in 16 years?
Scientists baffled to discover that Venus’ spin is slowing down
Why is Venus rotating 6.5 minutes slower than it was just 16 years ago?
http://www.mnn.com/earth-matters/space/stories/scientists-baffled-to-discover-that-venus-spin-is-slowing- down-0
February 17, 2012, 11:50 p.m.
In the solar-system-as-pocket-pool game theory, every ball can also be a pocket, depending on its relative mass. If the moon is the cue ball, did it also impart reverse english on Venus as part of its break?
As for why Venus’s rotation would be slowing, consider that Earth, in effect, is “burning rubber” as it rolls around the sun. Venus, relatively speaking, is skidding around with the brakes on. Both seek stasis, i.e. tidal lock.
There is Xenon 129 on Mars. This isotope can only be created
by nuclear weapon detonation. Maybe those aren’t impact craters.