"That has been a long-term ambition of earth scientists," geologist Damon Teagle told National Geographic News.

But a lack of suitable technology and insufficient understanding of the crust have long tempered that ambition. (Get an overview of Earth's magma and other layers).

Now, better knowledge of the Earth's shell and technological advances—for example, a Japanese drill ship equipped with six miles (ten kilometers) of drilling pipe—have put the goal within reach, according to a commentary in this week's issue of the journal Nature, co-written by Teagle, a geologist at the U.K.'s University of Southampton.

Even so, drilling into the mantle would be "very expensive" and would require new drillbit and lubricant designs, among other things, according to the paper.

But if all