ROV Jason heading to work. Click image for larger view and image credit.
Jason (ROV)
Jason/Medea is a remotely operated vehicle (ROV) system designed by the Woods Hole oceanographic Institution’s Deep Submergence Laboratory for scientific investigation of the deep ocean and seafloor. It is a two-body ROV system, with Medea serving in a tether management role that decouples Jason from surface motion.
Together they offer wide area survey capabilities with Jason as a precision multi-sensory imaging and sampling platform. Both Medea and Jason are designed to operate to a maximum depth of 6,500 meters (21,385 feet), are transportable, and can be operated from a variety of vessels.
Medea, shown on deck, serves as a buffer between Jason and the ship. Image courtesy of Woods Hole Oceanographic Institution.
Jason is connected to Medea by a neutrally buoyant tether that is 0.84" in diameter and approximately 35 meters long. Like the tow cable, it also uses three copper conductors and three single-mode optical fibers, but uses Spectra fibers to provide strength while reducing size and weight. The tether has a breaking strength of 41,000 lb. Medea weighs 1200 pounds in air and is maneuvered by controlling the surface ship’s position within a dynamic positioning reference frame.
Movements of the support ship maneuver Medea utilizing dynamic positioning. Jason is propelled by six DC brushless electric thrusters that provide about 600 pounds thrust in the vertical, longitudinal and lateral directions. The vehicle has excellent passive stability in pitch and roll. Jason is designed for detailed survey and sampling tasks that require a high degree of maneuverability. It weighs about 8,000 pounds in air but is neutrally buoyant at depth. Jason’s closed loop controlled dynamic positioning abilities make it a very maneuverable and stable platform.
Both Medea and Jason have been designed to be superior real time optical imaging platforms with high quality cameras and lighting. The vehicles work together to provide lighting for each other in a fashion not commonly available in other submersible systems. Medea is configured with a silicon intensified target (SIT) black & white camera for terrain identification and visual location of Jason when both are operating.
Jason's sample tray. Click image for larger view and image credit.
Jason's sample tray can be configured in a variety of arrangements to accomplish the Scientist's objectives. Typically, Jason will carry water samplers, push cores to collect seafloor cores (mud!), a "slurp" pump to collect critters, a temperature probe to record the ultra hot temps of water coming out of the hydrothermal vents. Many researchers wish to collect rocks which Jason collects with its manipulators. Up to 310 lbs of samples can be stored on Jason's tray and brought back to the surface.
Once Jason is in the water, it takes 3 people to operate it - a Pilot who "flies" the ROV, an Engineer who monitors all the systems (electrical, mechanical, hydraulic, etc) and operates the winch which pays out / hauls in the fiber optic cable which is attached to Medea and a Navigator who positions the research vessel so that Medea and Jason can operate in the desired area. Because the vehicles are capable of operating 24 hours per day, 3 shifts of people are required to run it. Therefore, 9 people go to sea with Jason - plus a 10th person who is responsible for organizing all the data which is collected!The first Jason ROV began its career in 1988 and retired in 2001. During that time, Jason made 253 dives with 4683 hours on the bottom! The longest dive the first Jason made lasted 117 hours. The new ROV Jason has been in operation since 2002. So far, 183 dives have been made with 3249 hours on the bottom.
The Web team gratefully acknowledges this contribution by Woods Hole Oceanographic Institution, Woods Hole, MA.
Related Links
