The best thing is when the chief scientist is so excited that he can’t sit down.
—Tito Collasius, Expedition Leader and Chief Pilot
The ROV Jason transports images back to the ship — images of corals and fish, crabs and squid, shipwrecks and fishing gear — with amazing clarity. The three high definition cameras, coupled with the sonar help create a mental map of the sea floor. For the scientists on board, finding that elusive solitary coral or long lost wreck makes them stand up with excitement. Built and operated by Woods Hole Oceanographic Institution (WHOI), Jason is a part of the Deep Submergence Laboratory and the National Deep Submergence Facility.
Just as in the Greek legend of Jason and the Argonauts, Jason is dependent upon Medea to perform tasks. In the legend, Jason is sent to find the Golden Fleece by King Aeedes. The King’s daughter, Medea, falls in love with Jason and aids him in completing his three tasks so that he can claim the fleece. He would not succeed without her. Likewise, our Jason needs Medea to operate.
When diving, Jason and Medea are a two part system that works in unison. A reinforced fiber optic cable links from the ship to Medea and a fiber optic tether leads on to Jason. The Medea acts as shock absorber, hovering in the water between the ship and Jason. There is enough line between Medea and Jason so if the ship were to bounce in the waves, the Medea would be tugged, but the Jason would remain in place. In addition to tethering the Medea and Jason, the cable carries power and commands down to the vessels, and images and data back to the ship. The Medea has a camera and lights, and can “watch” Jason work as well as help keep it clear of any potential entanglements such as stray fishing gear.
WHOI provides its own Launch And Recovery System (also know as LARS). This system allows the crew to safely move Jason (weighing about 9,000 pounds) into and out of the water. During the launch, Jason goes in first, over the port side, and is steered around behind the ship. Medea follows Jason and is launched with the A-Frame off the stern. They descend slowly, about 35 meters per minute, avoiding any hazards such as lost fishing gear. Jason can descend to 6,500 meters or just over 4 miles. Recovery is also a team effort. The line for retrieving Jason is zippered into a special sleeve on the tether. After Medea is on deck, the crew hauls the recovery line attached to Jason on board. When Jason is close enough, the sleeve is unzipped, and the recovery line is attached to LARS and spooled up onto a drum on the arm, lifting Jason out of the water and allowing it to be brought on deck.
A dive is similar to a complicated dance where each person must know his role. Instead of a stage, the players gather in a large metal box called the “Control Van,” a small portable lab on the deck of the ship. Filled with monitors, and the joysticks for maneuvering the vessels, the Van is the center of activity during the dive. The pilot steers Jason and manipulates the arms, collecting specimens and footage for the scientists. The engineer drives Medea, keeping her above Jason. The Navigator actually takes control of the ship and keeps the ship away from the line of Medea and Jason. The science team also has 3 people involved in each dive. The dive lead directs the dive, identifying specimens to be collected, and the path of the ROV. During the dive the lead narrates what he or she is seeing which helps with video analysis back on shore. The person serving as data recorder enters information into a database called the virtual van. Any notation, such as “Primnoa Coral” is time-stamped and photographed by the three cameras aboard, and water quality measurements are recorded. This information can be accessed later by any of the scientists. There is also a scientist whose primary responsibility is to keep track of the DVDs that are recording the dives, and starting new ones at the start of every hour. With dives that last 16 hours, the scientists work 4 hour shifts. The Jason crew works 5 hours shifts, which includes working in the van as well as the launch and recovery.
Jason was designed around the work that needs to be done. The ROV has a retractable basket in the front, and two swing arms, which come out from the sides. With manipulator arms on both corners, specimens can be collected and efficiently placed into any container. For this mission we have a set of large tubes, called “quivers” that we can close with rubber stoppers after putting a sample in. We actually have two sizes of stoppers, so we can place a small sample in the bottom, put a small stopper down in the tube, and then put a second sample on top and close it with a tight stopper. We have a bio box to keep larger specimens alive, and a set of push cores for sampling the sediment on the seafloor. Jason can bring approximately 350 pounds of samples to surface. Jason is always slightly buoyant, so the thrusters on board are used to steer and propel Jason to the target sites rather than to keep the ROV afloat.
The sensors, cameras and lights are tucked into the body of the ROV. The sensors collect water chemistry information such as salinity, dissolved oxygen, turbidity, and temperature. The three HD cameras provide 3 different views from Jason. In these areas, we start from the base of the canyon and move upward along the slope. That way the pilot can see what is ahead of him. If we tried to go down hill, it is impossible to see much of anything as the slope drops away and our view is out into the water column.
The weather has disrupted our plans of having Jason in the water from 4 am until 8 pm every day, but we are looking forward to some better seas, and having one of those experiences “where the chief scientist is so excited that he can’t sit down” as we explore the Norfolk and Baltimore Canyons.
Many thanks to Tito Collasius for his help with this post.