Wiring the world below

A network of permanent observatories will soon monitor the oceans

THE planet arrogantly dubbed “Earth” by its dominant terrestrial species might more accurately be called “Sea”. Seven-tenths of its surface is ocean, yet humanity’s need to breathe air and its inability to resist pressure means this part of the orb is barely understood.

In June a project designed to help correct that will open for business. The seven sites of the United States’ Ocean Observatories Initiative (OOI), scattered around the Atlantic, Pacific and Southern oceans, will measure physical, chemical, geological and biological phenomena from the seabed to the surface. They will join three similar Canadian facilities, VENUS and NEPTUNE in the Pacific, which have been operating since 2006 and 2009 respectively, and the Arctic observatory in Cambridge Bay, an inlet of the Arctic Ocean, which opened in 2012.

The American project was conceived jointly with Canada, which secured funding first. Canada’s near decade-long operational experience should help to provide pointers to make the bigger operation a success. The OOI’s metaphorical flagship is the Cabled Array, which is being deployed off the coasts of Oregon and Washington, to the south of VENUS and NEPTUNE, with which it will collaborate. In particular, these observatories have a remit to study a suboceanic piece of the Earth’s crust called the Juan de Fuca plate, which is being overridden by the North American plate’s progress westward as part of the stately geological dance called plate tectonics.

As its name suggests, the Cabled Array is organised around a submarine cable—a 900km-long power and data connection between its base in Oregon and its seven submarine nodes (see illustration). These nodes are linked, in turn, to 17 junction boxes that distribute power and signals to the system’s instruments, and collect data from them. It is also connected to “profiler moorings” that let instruments travel up and down a wire stretching from the surface to the bottom, allowing a cross-section of the water column to be sampled at regular intervals.

Strange life

One of the Cabled Array’s jobs is to measure the Juan de Fuca plate’s volcanic and seismological activity, including the output of its hydrothermal vents—submarine springs from which superheated mineral-laden water emerges. These support very unusual forms of life which are not found in any other habitat. It will also, though, study more quotidian matters, such as ocean currents and chemistry, and the biological productivity of the area.

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