Updated

It's no journey to the center of the Earth. Not yet, anyway.

But scientists do intend to drill the deepest hole ever made in the Earth's crust, deep beneath the oceans off the coast of Costa Rica, an effort to collect samples of the planet's mantle for the first time ever, according to a report at National Geographic News.

Samples pulled from deep within the planet -- extracted by a Japanese drill ship equipped with a whopping six miles of drilling pipe -- would rival moon rocks in terms of scientific importance, they claim.

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

Between Earth's molten core and hard, thin crust lies the roughly 2,0000-miles-thick mantle, which contains the vast bulk of Earth's rocks. But we don't know much about them, because all we have are bits that have come to the surface via volcanoes or those trapped in ancient mountain belts.

And existing mantle samples no longer really represent mantle conditions and makeup, experts say, since they've been altered in the long process of coming to the surface, so they providing only tantalizing glimpses of what lies below.

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

But if all goes as planned, drilling could begin by 2020, Teagle said. As soon as next month, the team will begin exploratory missions in the Pacific, where crews will "bore further into the oceanic crust than ever before," the paper says.

For more information, see the full story on National Geographic News.