In the Cold War '60s, as the space race heated up, another race began: to the center of the earth. Well, perhaps the Soviets and Americans couldn't drill quite that deep, but they could try to get to the so-called Moho, more formally the Mohorovicic Discontinuity, the theorized but much-disputed boundary between the mostly solid crust and the magma-filled mantle. After the launch of an American drilling program to reach the boundary, the Russians joined the race to drill the deepest hole in the world. Read More