July 19, 2020

“It has been said that the human race knows more about certain distant galaxies than it does about the ground that lies beneath its very feet. In fact, while it took the famous Voyager 1 satellite 26 years to exit our Solar System (relaying measurements to Earth from 16.5 billion km away), it took about the same amount of time for humanity to penetrate a mere 12 km into the Earth’s surface.” (Atlas Obscura)
The first real attempt to drill deep into the earth’s crust dates from the early 1960s when the Project Mohole was launched. The aim was to drill through the Earth’s crust to obtain samples of the Mohorovicic discontinuity, or Moho, the boundary between the Earth’s crust and mantle.
Project Mohole contracted with Global Marine of Los Angeles for the use of its oil drill ship CUSS I. Five holes were drilled, the deepest to 601 ft (183 m) below the sea floor in 11,700 ft (3,600 m) of water, off the coast of Guadalupe Island, Mexico. The project was cut short in 1966 due to lack of funding but set an important precedent for future off-shore drilling programs with the first use of the first dynamic positioning system.
In 1970, Soviet scientists started drilling the Kola Superdeep Borehole near Murmansk, Russia. They wanted to drill as deep as possible into the Earth’s crust with the main target depth set at 49,000 ft (15,000 m).
Drilling began on 24 May 1970 using the Uralmash-4E, and later the more powerful Uralmash-15000 series drilling rig. A large central hole was first drilled from which a number of boreholes were branched. Drilling progress was incredibly slow with a succession of drilling incidents, scientific investigations and search for technical solutions. On 6 June 1979, the world depth record held by the Bertha Rogers hole in Washita County, Oklahoma, USA, at 31,440 ft (9,583 m) was broken. In 1983, 10 years after the start of drilling began, the depth of 12,000 meters could be reached. The 8.7 inches hole reached 40,230 ft (12,262 m) in 1989. The SG-3 borehole became the deepest artificial point on Earth.
Because of higher-than-expected temperatures at this depth and location, 180 °C (356 °F) instead of the expected 100 °C (212 °F), drilling deeper was deemed unfeasible and the drilling was stopped in 1992. It is likely that the collapse of the USSR by the end of 1991, contributed to the abandonment of the project.
The researchers found out that there is water at 7.4 miles (12 km) into Earth’s crust, despite this previously being thought to be impossible. They also found 24 new types of long-dead single-celled organisms and gained access to rocks that were 2.7 billion years old.
These discoveries with the never-reached depth made people believe that many legends from the past are true. The hole was associated with Noah’s flood because water was supposedly drained into subterranean sinkoles. Some people still believe this is the proof and the flood wasn’t just a tale. Locals in the area say that the hole is so deep you can hear the screams of people being tortured in hell, hence its nickname being “the well to hell.”
No one tried to drill again to the earth mantle. Japan’s Agency for Marine-Earth Science and Technology (JAMSTEC) said in 2017 it plans to drill through 3.7 miles (6 kilometers) of oceanic crust to reach the mantle for the first time. The project is estimated to cost $540 million and is supposed to be carried out by Chikyu, a flagship Japanese ultra-deepwater drillship. The researchers said they hope to start the mission in the early 2020s, or by 2030 at the very latest.
(Source: Absolute Knowledge/Atlas Obscura/Wikipedia/Smithonian Magazine/IFL Science – Image: drilling the Kola superdeep borehole/Der Sontag)