What was the purpose of Project Mohole?

In 1961, American researchers began an Inner Space counterpart to the Cold War's Space Race. The plan was to drill into the Earth's upper mantle through the boundary between the planet's rocky outer layer and the top layer of its molten core.

To do that, they had to go through the Mohorovičić discontinuity, which Croatian Seismologist Andrija Mohorovičić discovered in 1909 by comparing the different types of waves from shallow-focus earthquakes. The discontinuity is also called “The Moho.” Hence, the name "Project Mohole."

In the first (experimental) phase, the team drilled five holes off the coast of Guadalupe Island. The deepest was a success, 601 feet beneath the sea bed, under 11,700 feet of Pacific Ocean. Drilling in water this deep, that far into the sea floor, from an un-tethered platform had never been done before. And the core sample revealed basalt beneath Miocene-age sedimentary soil.

Funded by the National Science Foundation, Project Mohole was the most famous undertaking of the American Miscellaneous Society. AMSOC was an informal group of researchers who studied un-commissioned research ideas submitted to the US Navy. Established in 1952, it disbanded in 1964.

Phase Two never began, as Congress pulled the financial plug on Project Mohole in 1966, because of rising expense. Researchers at the Soviet Union’s Kola Institute conducted a similar project at the same time and dug the world’s deepest hole, 40,220 feet, before giving up in 1989.