ROV Jason

ROV Jason/Medea

The remotely operated vehicle (ROV) Jason is actually a system made up of two vehicles--Jason and Medea. Together, these two vehicles enable scientists to survey and sample the seafloor without leaving the deck of their ship. The ROVs are named for the adventurous sea captain of Greek mythology and his wife.

ROV Jason being deployed in 2006.

Jason, which is about the size of a minivan, is the main vehicle. It is equipped with sonar imagers, water samplers, video and still cameras, and lighting gear. Its manipulator arms can collect samples of rock, sediment, or marine life. Medea, which is about the size of a small compact car, travels behind and above Jason. Medea’s lights illuminate the area around Jason and its cameras help the Jason pilots—who are on the ship at the surface, a mile or more above—guide the ROV.

Medea is linked directly to the ship by a tether that is 10 kilometers (6.2 miles) long and less than an inch in diameter. The tether carries fiber-optic lines that deliver electrical power and instructions from the ship to Medea, when then relays these to Jason, and data, photos, and video from the ROVs to the surface. Jason and Medea are linked together by a tether that is just 35 meters (114 feet) long.

Engineers in the Deep Submergence Laboratory at WHOI designed the Jason/Medea system with two “bodies” to protect Jason from movements of the ship at the surface. While the ROVs are on their mission, the tether connecting Medea to the ship is taut, but the one that links Medea and Jason remains slack. This allows Medea to serve as a shock absorber: If waves at the surface move the ship up and down, Medea will rise and fall, but Jason can continue to work undisturbed.

Jason is highly maneuverable. Its six thrusters give its pilots precise control in the vertical (up and down), longitudinal (forward and backward), and lateral (left to right) directions. It can hover a meter above the seafloor, nose into deep crevices, and pluck samples from a spot pinpointed by scientists on a ship two miles above.

The Jason pilots and scientists work from a control room on the ship to maneuver the vehicles and monitor Jason’s instruments and video. They follow the action at the seafloor on eight video screens, three from Medea and five from Jason.

The samples Jason collects can be placed in a basket on the vehicle, but the basket fills up fast. Returning to the ship to empty the basket and then diving back to the seafloor takes many hours—time that could be better spent gathering more samples. So the Jason engineers have devised ways to keep the ROV at the seafloor longer. Now, Jason’s manipulator arms can place samples on an “elevator,” a weighted, deep-sea platform that the team drops from the ship and that falls to the bottom. When the 6-by 6-foot elevator is loaded with samples, the Jason team on the ship signals it to drop its heavy weights. The buoyant elevator then rises to the surface, where scientists retrieve its valuable cargo of samples. All the while, Jason continues working a mile or more below.

Jason was first launched in 1988 and is now in its second generation, with a sturdier, more advanced vehicle having been launched in 2002. The system has been used for hundreds of dives to hydrothermal vents in the Pacific, Atlantic, and Indian Oceans. In 2010, it provided the first live look at an exploding underwater volcano.