In early December, the drill ship JOIDES Resolution will depart Colombo, Sri Lanka, and head for a spot in the southwestern Indian Ocean known as Atlantis Bank. There, it will lower a drill bit and try to screw it through 1.5 kilometres of rock, collecting a core sample as it goes. If all goes well, future expeditions — not yet scheduled or funded — will return and finalize the push into the mantle. Scientists first tried to reach the Moho in the middle of the twentieth century. In the 1960s, US scientists led ‘Project Mohole’, which drilled into the sea floor off Guadalupe Island, Mexico. The project reached a depth of just 183 metres before costs ballooned and Congress killed it. “We live on this Earth and we ought to know something about what happens beneath us,” says Walter Munk, an oceanographer at Scripps Institution of Oceanography at UC San Diego, who conceived Project Mohole with colleagues over cocktails one evening in 1957.