Ocean drilling programs are a series of scientific expeditions to study Earth beneath the ocean floor. Information gathered by these programs helps scientists understand the processes that have shaped Earth. Ocean drilling also provides information on the evolution of prehistoric marine life, changes in Earth’s climate during the past 200 million years, and the location of natural resources. The latest such program, the International Ocean Discovery Program (IODP), originally called the Integrated Ocean Drilling Program, began in 2003. The IODP continues the work of the Ocean Drilling Program (ODP) and the Deep Sea Drilling Project.
Ocean drilling programs use special ships called drillships. A long strand of pipe called a drill pipe passes through a hole in the ship’s hull. Machinery on the ship rotates the drill pipe, which bores deep into the ocean floor. Tools pass through the pipe to remove cylindrical samples of sediment and rock called cores. Cores may contain fossils and minerals that have accumulated over millions of years. Scientists have recovered cores in water more than 27,000 feet (8,200 meters) deep. In laboratories aboard the drillships, scientists analyze and catalog the cores. The cores are later moved to special libraries called core repositories. Once a core has been taken, scientists can place sensors inside the drilled hole to monitor temperature and pressure.
Teams of scientists from around the world participate in IODP cruises. Many nations contribute funding to the program. The ODP operated the JOIDES Resolution from 1985 to 2003. JOIDES stands for Joint Oceanographic Institutions for Deep Earth Sampling. The program identified populations of microbes living in hot water beneath the ocean crust and analyzed evidence of past climate change. It also studied natural gas hydrates, frozen deposits of methane gas and water that could someday be used for fuel. United States members of the IODP operated the JOIDES Resolution from 2003 to 2005. From 2006 to 2009, the U.S. partners rebuilt the JOIDES Resolution. The renovated ship resumed drilling in 2009. In 2019, the program studied iceberg movement in Antarctica, and in 2020, the geological history of the Amazon River basin.
Japanese members constructed a heavy drillship named the Chikyu, the Japanese word for Earth. The ship can drill up to 23,000 feet (7,000 meters) into the ocean floor, more than three times the depth of any previous research drillship. The ship has been used to investigate earthquake fault lines and natural gas hydrates. In 2016, it studied microbes living below the ocean floor to learn how deep life can survive. European IODP partners have provided equipment for special missions, such as icebreakers for expeditions to the Arctic Ocean.
The Deep Sea Drilling Project operated the drillship Glomar Challenger from 1968 to 1983. Among its many achievements, the project provided data to support the theory of plate tectonics. The theory holds that Earth’s surface is made up of rigid plates moving about on a layer of hot rock. The project produced evidence that newly created sea floor spreads from underwater ridges, a key element of tectonic theory (see Plate tectonics).
See also Ocean (Tools of exploration).
