June 11, 2008 -- It's easy to magnetize iron: rub it with a magnet. But how do you magnetize the iron core of Earth?
By spinning a 26-ton steel sphere filled with boiling metal at about 90 miles an hour, Dan Lathrop, a scientist at the University of Maryland, hopes to unlock Earth's spinning magnetic heart.
In the process he would create the world's first artificial, spherical and self-sustaining magnetic field, or dynamo, which could predict fluctuation in the Earth's magnetic field. This fluctuation damages electronics in orbit and on land.
"If you can predict a hurricane coming, you can manage the damage," said Lathrop. "We could have a predictive science for what happens inside the Earth's magnetic field."
What begins inside the Earth doesn't stay there. Besides pointing compasses north, the magnetic field acts like a protective shield, blocking harmful particles from the sun, which fry the electronics on board orbiting satellites and mess with the electrical grids powering homes and offices on Earth.
Some researchers speculate that without a magnetic field, technology on Earth would have had a much more difficult time.
That shield is generated by superheated iron moving about a tenth of an inch each second deep in the planet's core.
That admittedly sounds simplistic, but the movement generates a changing magnetic climate the same way the planet's rotation creates weather.
And just like predicting the weather is an inexact science, predicting magnetic weather can be a tough job.
If researchers understood more about how the dynamo at the center of the Earth operates, they could help protect satellites and electrical grids, while explaining a scientific mystery: why the strength of the Earth's magnetic field has decreased by about 10 percent over the last 150 years and continues to do so.
Recreating the dynamo that powers Earth's magnetic field, or any dynamo for that matter, has proven difficult. Only a handful have ever been created, and only using complicated piping and settings that don't resemble a planetary dynamo.
"It's easy for the planet to create a dynamo because it's so big," said Peter Olsen, a researcher at Johns Hopkins University in Baltimore, Md., who was not involved in the sphere research. "It's much harder in the lab."
The Maryland experiment is much smaller than the Earth's core, so to make up for its lack of mass, Lathrop's inch-thick steel sphere, 10 feet in diameter, will have to spin much faster -- at about 1,500 inches each second -- and use more electrically conductive sodium instead of iron.
"He's in the right region where [a dynamo] could happen," said Olsen about Lathrop's effort.
Hopefully Lathrop and his lab will survive his creation.
Currently Lathrop is testing the spinning sphere with water, but within six months he hopes to have the sphere filled with boiling sodium.
Sodium reacts with water to create burning hydrogen gas.
"We've already had three meetings with the local fire department," said Lathrop, who has disabled the water sprinkler system in the room.
"We need to train everyone to just let it burn and not add water if something happens," said Lathrop.
Related Links:
Eric Bland's blog: Interior Design
Discovery News blog: Earth Impacts
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