Scientists measure phenomenon that powers Earth's magnetic field

WASHINGTON, June 1 (UPI) -- A phenomenon called geodynamo powers the Earth's magnetic field; it is the motion of liquid iron in the planet's outer core.

Researchers aren't sure how the phenomenon originated. They're also puzzled as to how its been maintained throughout Earth's history.

With aims to unveil these mysteries, scientists with the Carnegie Institution for Science are working to better understand the formation and evolution of the Earth's inner core and outer core.

As hunks of rocks orbiting the sun coalesced to form the early Earth, the heavier, denser materials sank to form the core, while lighter materials formed the mantle and crust. The inner core is solid iron, while the outer core is a liquid iron alloy.

To study the behavior of these materials, researchers must recreate the extreme conditions of deep earth.

"We sensed a pressing need for direct thermal conductivity measurements of core materials under conditions relevant to the core," Alexander Goncharov, a researcher with Carnegie, said in a news release. "Because, of course, it is impossible for us to reach anywhere close to Earth's core and take samples for ourselves."

Researchers used a laser-heated diamond anvil cell to recreate the extreme heat and pressure of the core. Material is squeezed between two diamonds to create intense pressure, while the laser supplies the heat. The scientists measured the heat conductivity of a variety of iron samples under these conditions.

The experiments -- detailed in the journal Nature -- showed iron is able to conduct heat at energy levels registering on the low end of previous estimates, between 18 and 44 watts per meter per kelvin.

In other words, the energy to sustain geodynamo has been available since the very beginning of Earth's history.

"In order to better understand core heat conductivity, we will next need to tackle how the non-iron materials that went along for the ride when iron sunk to the core affect these thermal processes inside of our planet," Goncharov said.