As the JOIDES Resolution arrived in Galveston, Texas, last September after completing its 110th and final Ocean Drilling Program (ODP) expedition, scientists celebrated the many advances made during the program. During its nearly 20 years of operations, ODP collected more than 700,000 feet of core from 1,700 holes — advancing our understanding of climate change, earthquakes, natural resources and microbiology. Yet much of the seafloor remains to be explored.

The derrick was installed on the center of the Chikyu in the Nagasaki Shipyard and Machinery Works on Sept. 26, 2003. Lifting the derrick, which is 92 meters tall and weighs 1,200 tons, required Kaisho, Japan’s biggest crane ship. All images courtesy of the Integrated Ocean Drilling Program.

Although the number of holes drilled by ODP is impressive, it only represents one hole per an area about the size of Colorado. The Integrated Ocean Drilling Program (IODP), which began on Oct. 1, 2003, will continue the exploration started by ODP and, before that, the Deep Sea Drilling Project, to investigate Earth’s regions and processes that were previously inaccessible and poorly understood.

Scientific vessels

The most visible difference between IODP and its predecessors is the use of multiple vessels for exploration. Three different types of drilling vessels — riser, riserless and mission-specific platforms — will be available to achieve the program’s scientific goals. The riserless and mission-specific platforms will begin work this summer with respective expeditions to the Pacific northeast and the high Arctic. Like its predecessors, IODP expeditions are proposal-driven and are planned after extensive international scientific and safety review.

Aboard these vessels, IODP proposals will address three main themes raised in the IODP Initial Science Plan, Earth, Oceans, and Life — the deep biosphere and subseafloor; environmental change, processes and effects; and solid earth cycles and geodynamics. The different capabilities of the vessels make each integral to achieving the goals set forth in the plan.

Riser vessel

Supplied by Japan and led by the Japan Marine Science and Technology Center, a new research platform for IODP is the Chikyu (which translates to “Earth”), a massive riser vessel that is 210 meters long. It will eventually have a 12,000-meter drill string for coring in water depths up to 4,000 meters. Still under construction, it will begin international operations in late 2006, most likely spending the first several years studying the seismogenic zone in the Nankai Trough off Japan.

Riser technology will allow IODP to conduct long-term (many months to yearlong) expeditions in areas previously inaccessible to scientific ocean drilling. The riser, a metal tube extending from the seafloor to the Chikyu, contains a device to prevent blow-out, which allows for drilling in areas with hydrocarbon potential. It also uses drilling mud rather than seawater as a drilling fluid, which is advantageous in unstable holes or areas with slow penetration.

Using a riser vessel will also allow scientists to drill holes deep into the crust at both passive and convergent margins and will thus be invaluable to studying the solid Earth cycle: the breaking apart of continents and formation of sedimentary basins; the creation, evolution, and recycling of oceanic and large igneous province lithosphere; and the creation of new continental lithosphere.

Drilling, logging and installing observatories by both the Chikyu and the riserless drillship will also provide information on the behavior of rocks, sediments and fluids in the seismogenic zone — the region where most earthquakes are generated. Drilling will also advance our progress toward a goal made in the 1950s, a goal that spawned all ocean drilling programs: drilling to the mantle beneath ocean crust. IODP plans to recover a complete section of oceanic crust and uppermost mantle generated at a fast-spreading ridge in an effort known as the “21st Century Mohole.”

Riserless drilling

The United States — through the alliance of the Joint Oceanographic Institutions (JOI),Lamont-Doherty Earth Observatory of Columbia University and Texas A&M University — will operate a riserless drillship, similar to the vessel used in ODP. In fact, for the first year, it will be the same vessel — the JOIDES Resolution. Riserless drilling is most effective in moderate to deep water and allows for sampling over the majority of the world’s oceans.

Riserless drilling is also key to looking at the deep biosphere and subseafloor ecosystem. Scientists will study the microbial populations that live beneath the seafloor, as well as characterize fluid flow in the crust. IODP plans to define the environmental conditions that support and limit the subseafloor biosphere, as well as evaluate the biogeochemical impacts of the microbiota. IODP will also continue the research conducted by ODP on gas hydrates, with aims to determine hydrate dependence on microbes and quantify rates at which the gas is generated.

The Resolution sets sail on its maiden IODP voyage in June to explore fluids in the oceanic crust at the Juan de Fuca Ridge in the northeast Pacific Ocean. It will conduct five expeditions over the next year (see sidebar) before an approximate year-long hiatus in drilling. During this time, a vessel (the Resolution or a similar vessel) will be converted to meet the long-term needs of IODP. Riserless expeditions are then expected to resume on the upgraded ship in mid-2006.

Mission-specific platforms

An expedition to the Arctic will take place this summer — the first major drilling expedition conducted there. A proposal to drill on the Lomonosov Ridge in the central Arctic Ocean to study climate change and paleoceanography was the highest ranked proposal for the final years of ODP, but the program was unable to conduct the expedition.

Sedimentologists and petrologists take turns describing cores recovered by the JOIDES Resolution. For the first year of operations, scientists will continue to conduct experiments aboard the Resolution — as part of the Integrated Ocean Drilling Program.

The logistics for a mission to the Arctic are complex — coordinating three icebreakers from different countries during the limited weather window of six to eight weeks each summer when drilling is most feasible. IODP plans to use the Vidar Viking as the scientific drillship, the Swedish icebreaker Oden, and a third unnamed icebreaker to support the mission during the voyage this summer. Through the expedition, scientists hope to understand both the long-term climate history of the central Arctic Ocean and its role in Earth’s transition from one extreme (Paleogene greenhouse) to another (Neogene icehouse with glaciation at both poles). They also hope to gain insight into the shorter-term climate history, connecting the Arctic Ocean to the North Atlantic Ocean at sub-millennial scale resolution.

The European Consortium for Ocean Research Drilling, made up of 13 European countries, will operate this and future mission-specific expeditions in shallow waters and in ice-covered regions. These expeditions will be vital to achieving IODP’s initiatives of understanding extreme climates and rapid climate changes. Although no future expeditions have been scheduled, scientists expect to drill in the Tahiti/Great Barrier Reef area in 2005 to study sea-level rise and climate change over the past 20,000 years.

International funding

Not only will IODP’s multiple platforms obtain records worldwide, but support for the programs will also be global. In that way, the international composition of the scientific parties and advisory committees will differ from ODP.

During ODP, the United States contributed more than 50 percent of the costs and therefore had half of the berths and membership on advisory committees. The remaining 22 members shared the rest of the berth space and committee seats in proportion to their financial contributions. In IODP, the United States and Japan are equal partners, known as “lead agencies.” Organizations in other countries, particularly European ones, will also participate at a significant level. Although the proportion of U.S. scientists will decrease on each leg, the increased number of platforms will allow for greater U.S. participation overall. Meanwhile, opportunities for scientists from other nations will increase in both relative and absolute terms.

Finally, scientists will notice the involvement of more funding agencies and organizations. Because there are multiple lead agencies, each operating a vessel, IODP Management International has been established to manage the program’s science operations. Furthermore, many countries have established national programs to provide for their scientists, such as the U.S. Science Support Program. Education and outreach opportunities will be conducted at all levels of IODP, providing a much stronger presence than in previous programs.

Beyond the science

When the active phase of drilling in IODP commences in June of this year, nearly a decade of planning for IODP will begin to draw to a close. During this planning effort, the scientific imperatives of the program have been well defined. The goals have provided the rationale for nearly 20 nations around the globe to come together for the third phase of ocean drilling. These countries have done so based on the conviction that the research to be undertaken will provide results and understanding that will inform debate on many topics of global significance, including climate change, sea-level rise, the carbon cycle, geologic hazards, methane hydrate and other potential mineral and energy resources.

JOI President Steven Bohlen recently spoke to the IODP Science Planning and Policy Oversight Committee about broadening the goals of the program to extend beyond the initial science plan. “The success of IODP will not be measured only in terms of enhanced scientific understanding and discovery,” Bohlen said. “Success will be measured by how much the public learns to appreciate that Earth’s oceans are a critical, yet vastly undersampled and unexplored, part of the earth system.”

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