News in Science

Scientists to mimic earth's spinning core

A team of scientists in the United States are hoping to create a miniature version of the earth's core and in the process discover why its effect is waning.

Professor Dan Lathrop and his team from the non-linear dynamics laboratory at the University of Maryland have constructed a 26-ton steel sphere that will be filled with boiling metal and spun.

In the process he hopes to create the world's first artificial, spherical and self-sustaining magnetic field, or dynamo, which could predict fluctuations in the earth's magnetic field.

"If you can predict a hurricane coming, you can manage the damage," says Lathrop.

"We could have a predictive science for what happens inside the earth's magnetic field."

Protective barrier

Besides pointing compasses north, the earth's 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 quarter of a centimetre each second deep in the planet's core.

It 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 centre of the earth operates, they could help protect satellites and electrical grids.

They may also help explain why the strength of the earth's magnetic field has decreased by about 10% over the last 150 years and continues to do so.

No easy task

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," says Peter Olsen, a researcher at Johns Hopkins University in Baltimore, 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 thick steel sphere, which is 3 metres in diameter, will have to spin much faster - at about 3.8 metres per second - and use more electrically conductive sodium instead of iron.

"He's in the right region where [a dynamo] could happen," says Olsen about Lathrop's effort.

Highly reactive

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," says 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," says Lathrop.