Nodes, Sensors, and Internet Access at the Bottom of the Ocean

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Nodes like this one will provide both power and bandwith to a multitude of seafloor sensors.

On September 1st the 274-foot Naval research vessel Thomas G. Thompson pulled into Newport, Oregon. Its crew of researchers, engineers, graduate and undergraduate students – and one dean – had just completed a three week expedition called Visions ’11 to survey and assess the installation of an underwater network of sensors in the Pacific Northwest. When it’s completed the network will form an underwater observatory that simultaneously measures changes to the ocean’s physical, chemical, biological and geological processes. This kind of holistic approach to exploring the ocean may afford researchers a better understanding of how the different processes are linked. It is a shift away from typical ship-based research in which sensors or submersibles descend for a period of time, collect data, and are then retrieved. The new approach that could revolutionize oceanography.

The expedition is part of a broader effort called Ocean Observatories Initiative (OOI). Funded by the National Science Foundation, the OOI’s mission is to establish a fully integrated sensory system on the seafloor that will collect data for decades. When everything is in place the OOI observatory will be an oceanographer’s dream of underwater analysis fun. Located about 300 miles off the Oregon coast, the observatory will have 16 sensors to study the seafloor and 17 sensors to study the column of water between the floor and the surface. Measurements include magma activity beneath the seafloor, flow from the hydrothermal vents, sediment movement, life-attracting pockets called gas hydrate formations and water flow at multiple locations. Sensor packages are stuffed with a boggling array of instruments.

The remote operating vehicle ROPOS can survey the seafloor and deploy the power-supplying nodes.

To name a few, there’s a seismometer to monitor tectonic plate activity, a hydrophone to measure wave patterns, a mass spectrometer to determine chemical concentrations, even a DNA sampler. A fluid sampler will be used to take temperature, acidity, pressure, osmolarity, and a bunch of other aquarium-like metrics. And high-definition cameras with strobes will take still images of the vents and plant life. In the future researchers envision installing robots that will perform DNA analysis of many microbes living near thermal vents right there on the seafloor. High above the seafloor arrangement will be a float instrument package with a similar suite of sensors. Taking the same measurements from above and below will give scientists a 3-D assessment at an unprecedented level of detail.

The impressive sensory technology is matched by the technology that powers it and allows it to communicate with researchers. These capabilities are delivered by five nodes that the sensors will plug into. You can think of them as electric outlets and internet connections at the bottom of the ocean. Except these “routers” are carrying 10 Gb/s of bandwidth – probably overkill for Netflix streaming – that allow the instruments and robots to transmit data and receive instructions from land-based operators nearly instantaneously. Connecting the nodes are 560 miles of fiber optic cables, the same kind of subsea fibers that telecommunications companies use to link their networks. The network’s upgradeable too, as the nodes can be daisy-chained with these fibers to expand the network in the future.

This fluid flow meter measures water flow rates and analyses the water's chemical composition in three dimensions.

The main purpose of the Thompson’s expedition was to survey and assess the nodes and the cables that will support the multitude of sensor instruments. To do this they used an underwater glider and a robotic remotely operating vehicle. In addition to taking pictures of the nodes and cables, the ROV can be used to adjust node positions. The researchers took it for a test run. You can check out videos of this robot in action on the Visions ’11 website.

Many sites of interest to scientists are found at harsh locations. The hydrothermal vents that are teeming with life, such as tubeworms, crabs and anemones, spew acidic water that is more than 300 degrees Celcius. Corrosive patches of crystalline material called gas hydrates are of interest because they are often surrounded by rings of chemosynthetic life such as bacteria or mussels. When storms hit, ocean basins can become tempests with waves over 30 feet high. Not to mention the pressure at depth is 300 times that on land. But the observatory was built to last. Researchers expect it to produce continuous data – 24/7/365 – for at least 25 years.

Oceans cover almost 70 percent of the Earth and the dynamic process that churn beneath the surface impact ecosystems on land. So studying those processes is integral to maintaining a habitable planet. But it hasn’t been an easy task. Exploring the depths with manned submersibles is only possible for short lengths of time and sensors on satellites can only penetrate the few meters below the surface. The OOI will enable a human telepresence from which we can continually and simultaneously study multiple features of these dynamic ocean processes.

The ROV encounters "Pillars of the Ocean" – columns of basalt that form as lava drains out of deep lava pools.

It just so happened that the ocean was recently quite dynamic not too far from the observatory. This past spring a volcano, that is one of OOI’s primary study sites, erupted. The volcano is quiet at the moment, but they expect to capture subsequent lava flows on camera and track resulting changes to the volcano. “We are excited to be working at [the site] so soon after the latest eruption,” University of Washington oceanographer Deborah Kelley, one of the expedition’s leaders, said in a press release. “Using a remotely operated vehicle, we are able to conduct surveys that will help determine the extent and amount of new lava flows, and assess the life forms that are already beginning to re-appear at the site.”

Like computer chip-sized space ships that form swarms of sensors, OOI’s observatory at the bottom of the ocean represents a paradigm shift in exploration. When the observatory goes online in 2014 researchers won’t be the only ones to benefit from the new types of data. The real-time data will be streamed online so that other researchers and the public as well can follow the findings and access the otherworldly videos that will no doubt result. The observatory’s price tag – $153 million – is paid for with taxpayer money. The unique data to be collected in the coming decades will be a nice return for oceanographers and for the rest of us.

[image credits: Ocean Observatories Initiative and Interactive Oceans]
image 1: node
images: seafloor
images: shipboard

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