Geologists have spent decades trying to punch through Earth’s crust to reach the mantle, the vast rocky layer that makes up most of the planet’s volume. In 2023, an international team working from a research ship in the Atlantic came closer than any previous effort, pulling up an unprecedented length of mantle rock that effectively put human hands on material from just beneath the crust. Their success did not quite break through to the mantle’s full depths, but it did bring science to the threshold of a region that shapes everything from plate tectonics to the conditions that may have nurtured the first life.
The new core, drilled into an underwater mountain near a hydrothermal field, is the latest chapter in a long-running race to understand what lies beneath our feet. It builds on earlier deep drilling projects on land and at sea, and it is already reshaping how researchers think about the mantle’s chemistry, the circulation of seawater through oceanic plates, and the energy sources that sustain strange microbial ecosystems in the dark. I see it as a moment when a once‑fantastical “Journey to the Center of the Earth” finally brushed against reality.
Why the mantle is such a big scientific prize
To understand why scientists are so determined to reach the mantle, it helps to remember that this layer is not a thin shell but the bulk of the planet. Educational material on deep Earth notes that the mantle accounts for roughly 45 percent of Earth’s volume, a colossal reservoir of rock that slowly convects and drives plate motions at the surface. That slow churning powers earthquakes, volcanoes, and the creation of new crust at mid‑ocean ridges, so any direct sample of mantle rock is a window into the engine room of plate tectonics, not just a geological curiosity.
Most of what researchers know about this region still comes from indirect clues, such as seismic waves and fragments of deep rock that volcanoes fling upward. Those methods have revealed broad structures but leave big gaps about fine‑scale chemistry, water content, and how heat moves through the boundary where crust meets mantle. That is why projects that recover intact mantle rock, including the recent record core and earlier efforts described by EarthDate, are treated as breakthroughs rather than routine fieldwork.
From Kola to the ocean: a history of drilling toward the deep
The quest to reach the mantle began long before the latest Atlantic expedition, and some of its most dramatic scenes played out on land. In the late twentieth century, Soviet engineers sank what became known as Kola Superdeep Borehole in Russia, ultimately reaching a depth of 40,230 feet into the crust. That project never pierced the mantle, but it did reveal rocks far hotter and more fractured than expected, along with ancient formations dating back 2 billion years, and it set a benchmark for how difficult deep drilling can be even in stable continental crust.
As the limits of land‑based drilling became clear, attention shifted to the oceans, where the crust is thinner and the mantle lies closer to the seafloor. Programs that evolved into the modern International Ocean Discovery Program began sending specialized drill ships to mid‑ocean ridges and subduction zones, targeting places where tectonic forces had already thinned or uplifted deep rock. The JOIDES Resolution, a workhorse research vessel, became central to this strategy, using long strings of pipe to bore into underwater mountains and retrieve cores that hinted at mantle material even when the drill stopped short of the boundary itself.
The Atlantic expedition that “knocked on the mantle’s door”
The latest leap forward came when members of the International Ocean Discovery Program, working from the JOIDES Resolution, targeted an underwater mountain near a hydrothermal field in the Atlantic. Reporting on the project notes that it was here, 800 meters south of a key reference point on the seafloor, that the team in May 2023 drilled into unusually exposed deep rock and recovered the longest continuous section of mantle‑derived material ever obtained. The description that scientists had “knocked on the mantle’s door” captures how close this core brought them to a long‑imagined goal, even if a thin rind of altered rock still separates the borehole from pristine mantle below, as detailed in Feb.
The operation was part of Expedition 399, a cruise that scientists on board described as nearing its halfway point with “significant wins” already in hand as cores piled up on deck. Updates from Expedition 399 emphasized that the recovered rocks were not just deep but also remarkably intact, giving petrologists and geochemists a rare chance to trace how seawater circulates through the crust and into the upper mantle. A separate account of the same work highlighted that the site lay near a field of carbonate chimneys often compared to a “Lost City,” a place where mantle‑derived fluids seep into the ocean and build towering structures, as described in coverage of Lost City.
What the record core reveals about life’s origins
What makes this core more than a technical feat is what it can say about how life might have started. The drilled mountain sits where the African Plate meets the North American Plate, in a region where seawater percolates deep into mantle rock and triggers chemical reactions that release hydrogen and methane. Researchers have argued that similar reactions in the early ocean could have powered the first microbial metabolisms, and the new core lets them test that idea by examining fresh samples of the altered mantle, a point underscored in analyses of Scientists Drill Record Breaking Depth.
Microscopic studies of the recovered rocks show networks of fractures and mineral veins where fluids once flowed, and in some cases still do. One report describes a mantle rock sample viewed under a microscope by Johan Lissenberg, revealing textures that record repeated cycles of alteration as seawater interacted with olivine and other mantle minerals. Those textures help researchers estimate how much hydrogen such systems can produce over geologic time, and how stable the chemical gradients are that microbes might exploit, as detailed in Johan Lissenberg.
How this effort fits into a broader mantle‑drilling campaign
The Atlantic core is not an isolated triumph but part of a coordinated push to finally sample the mantle directly and systematically. In the spring of 2023, an expedition of scientists got closer to making a Journey to the Center of the Earth than ever before, as one account put it, by targeting a site where tectonic spreading had already thinned the crust. That work, which involved researchers such as Lesley Anderson and others, framed the new core as a stepping stone toward future holes that might finally cross the crust‑mantle boundary, as described in In the spring expedition.
On shore, universities are lining up to join the next phases. LSU highlighted how its faculty signed on to a project explicitly titled “LSU Professors Join Historic Effort to Drill Earth’s Mantle and Retrieve Rare Deep-Earth Samples,” describing it as one of the final legs in a long campaign to recover rocks never before observed. That announcement framed the International Ocean Discovery Program as the umbrella for multiple cruises that will share tools, data, and expertise, with the goal of eventually bringing back unaltered mantle peridotite, as laid out in Professors Join Historic to Drill Earth.
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