Riding to Earth’s core

A scientist has thought up a way to send a probe deep into Earth.


This cross section shows Earth's layers, from the hard crust of continents on the outside to a solid, iron-rich inner core (shown red and orange).


Ever wonder what you’d find if you could travel to the center of the earth? Someday, we might find out, says geophysicist David Stevenson of the California Institute of Technology.

Stevenson has thought up a way to send a probe to Earth’s core. For now, his plan is mostly just a cool idea. Quite a few obstacles keep it from being practical.

So far, the deepest anyone has drilled into the earth is 10 kilometers. The hard crust of continents probably goes down at least another 200 kilometers. Below that lies a gooey layer called the mantle, which surrounds a liquid outer core and a solid inner core. Both inner layers are made mostly of iron.

Stevenson’s idea is to blast a hole 300 meters deep and 10 centimeters wide. Into the hole, he would pour melted iron, which would flow downward and create enough pressure to push the crack to Earth’s center. He estimates it would take the probe about a week to get there.

Blasting a big enough crack would take about the same amount of energy as that contained in a basic hydrogen bomb.

The biggest challenge would be building the probe. The center of the earth gets so hot and there is so much pressure that most metals would melt. Electronic equipment would fall apart.

If scientists can ever find a way around those obstacles, they might get a new view of some of Earth’s deepest secrets.

Going Deeper:

Perkins, Sid. 2003. Going down? Probe to ride to Earth’s core in a mass of molten iron. Science News 163(May 17):307-308. Available at http://www.sciencenews.org/20030517/fob2.asp.

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