In 2005, the Integrated Ocean Drilling Project (IODP), an international marine research program, drilled about 4,600 feet below the ocean floor. That is about 1,000 feet away from the Mohorovicic discontinuity, also known as the mantle. The drilling took over 8 weeks, and was the third deepest drilling into the Earth’s center. The Earth’s radius is roughly 4,000 miles, and its interior consists of three main layers; crust, mantle, and core. The mantle makes up most of the Earth, holding about two-thirds of its mass.
It was announced earlier this year that scientists would like to reach the mantle within the next decade. They are currently investigating potential drill sites off the coasts of Hawaii, Baja California, and Costa Rica. The crust of the Earth is 18-36 miles think under the continents, and only 3.6 miles think under the ocean, hence why the focus is on off-shore sites.
Researchers would prefer to drill in the shallowest water; however that will not provide the coldest water which is advantageous to assist in cooling of the drill as it works. The drill will be in regions so deep that the temperature will reach a whopping 570 degrees Fahrenheit, coupled with immense pressure measuring 4 million pounds per square foot! And for those picturing another Gulf oil spill, take ease, as there are no oil or gas deposits to penetrate in mid-ocean, so no chance of a blowout.
To accomplish the job they are looking at tools the oil and gas industry uses, primarily a riser system. Riser systems consist of an outer pipe surrounding the drill string, the steel pipe through which samples are recovered. The problem with this system is that the largest current model available is only 8,200 feet long, and they would need to fabricate a model that is over 13,000 feet to do the job. This will be difficult, as the added length means added weight, so they are looking for alternative metals to replace the steel that is used in this system.
The IODP is currently funded by 24 nations, principally supported by the US and Japan. It was initially conceived in 2003 as a 10-year earth science research program comprised of universities and research centers from its member nations. The researchers hope to learn about the consistency of the mantle to see if they can learn anything about seismic conditions as well as the Earth’s evolution. To do this they need to sample the chemical makeup of the mantle. While this project is several years away from fruition, researchers are optimistic that potential discoveries could lead to life saving technology such as predicting weather patterns, oceanic storms, and earthquakes. And maybe their next discovery will be to see if you really can dig a hole to China!
Inside the Earth; a description of the location of the mantle. Courtesy of NASA.
Justin Harmon, Senior Editor