NOAA Ship Okeanos Explorer 2013 ROV Shakedown and Field Trials in the U.S. Atlantic Canyons

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A key purpose of NOAA’s Ocean Exploration Initiative is to investigate the more than 95 percent of Earth’s underwater world that, until now, has remained virtually unknown and unseen. Such exploration may reveal clues to the origin of life on Earth, cures for human diseases, answers on how to achieve sustainable use of resources, links to our maritime history, and information to protect endangered species.

Exploring the seafloor—a deep, dark, and cold environment—is extremely challenging. Because much of the ocean is so deep, scientists cannot simply don wet suits and use SCUBA gear to explore them. Instead, they often use high-tech robots, called remotely operated vehicles (ROVs), to learn about this extreme environment.

ROVs are marvels of engineering. They can carry instruments, conduct surveys, and collect vivid underwater imagery while allowing scientists to follow their progress from the safety of a ship.

The primary objective of this shakedown cruise is to operationally test a new ROV that will be operated from the NOAA Ship Okeanos Explorer. The vehicle weighs in at 9,200 pounds, has an overall length of 10.5 feet and stands an impressive 8.5 feet tall. It carries a minimum of six underwater video cameras, two of which are high definition, and a large array of the newest LED lighting technology and boasts an available sensor payload of over 400 pounds. Two seven-function hydraulic manipulators, a hydraulically actuated sensor platform, full-color sector scan sonar and a fully integrated inertial navigation system are all standard capabilities of the new system.

During a shakedown cruise, the ROV engineers need a range of seafloor bottom types to test the ROV’s different systems. The Okeanos Explorer will head to the submarine canyons off the northeastern U.S., where there are diverse seafloor habitats and bottom types ranging from very flat areas at the base of the canyons to valleys that provide very complex terrain with steep slopes.

The ROV is the key technology being used for this exploration. ROVs have several important advantages when compared to human-occupied submersible vehicles:

• Robots involve much less risk to human life and are able to visit places that are simply too dangerous for humans;
• Underwater robots are less expensive and can be much smaller and simpler to operate than human-occupied vehicles; and
• For many missions, underwater robots can operate faster than human-occupied vehicles and can remain underwater for much longer periods of time.

Regardless of their shape or size, underwater robots include several basic systems:

• Buoyancy Control - Underwater robots are generally heavy, but they must be nearly weightless when they are in the water. This requires some type of floatation, and if the ROV is expected to operate in deep water, the floatation has to be able to withstand very high pressures. At a depth of 4,000 meters, for example, the pressure is more than 6,000 psi. Many ROVs use a type of floatation material called "syntactic foam," which is made from tiny, hollow glass balls mixed into epoxy resin. This construction makes the foam about as heavy as pine lumber, but it can handle the pressure at 4,000 meters without collapsing.
• Propulsion - At present, most underwater robots use electric motors called thrusters, which are fitted with propellers. ROVs that operate near the seafloor usually have at least three motors to control motion in the left/right, forward/reverse, and up/down directions.
• Power - If a power system is carried onboard an underwater robot, this almost always means batteries, and that in turn means additional weight. Some ROVs overcome this problem by having power supplied through the umbilical cable that connects the ROV to its surface support vessel.
• Information Gathering - Video cameras are one of the most common information gathering systems, but many underwater robots can carry other equipment including sonar mappers, magnetometers for finding shipwrecks, water chemistry sensors, and manipulator arms for collecting samples.
• Communication - Most ROVs are in constant contact with human pilots via the umbilical cable that connects to the support ship.

Some ROVs also include navigation equipment that can precisely locate the robot’s geographic position. Ordinary Global Positioning System (GPS) equipment will not work for this because satellite signals do not penetrate very far into the ocean. Instead, acoustic devices called short baseline or ultra-short baseline positioning equipment are used to determine the ROVs position relative to the surface ship. These devices are based on the same principles as sonar, and can be combined with GPS data from the surface ship to accurately determine an ROV’s position underwater.