View Platform

Hercules is one of the very few Remotely Operated Vehicles (ROV) specifically designed to be used as a scientific tool. Built for the Institute For Exploration (IFE), Hercules is equipped with special features that allow it to perform intricate tasks while descending to depths of 4,000 meters (2.5 miles). Although Hercules was designed primarily to study and recover artifacts from ancient shipwrecks, it is also well suited to study biology and geology in the deep sea. Along with a flexible set of tools that can be adjusted to specific requirements of each dive, Hercules also has a pair of manipulator arms attached to its front end. One of these arms is force-reflective, which means that the operator can feel the forces being applied to the arm through motors in the operator's master control unit. Hercules carries an array of cameras and acoustic sensors that are used to gather video and other data during each dive. Most important, a High-Definition (HD) video camera allows scientists to closely examine the dive site and monitor operations using very high resolution video. A pair of still cameras can be used to accurately measure the depth and area of the research site, and to create "mosaics", large images built up from many smaller images. Other sensors measure pressure (which gives depth), water temperature, oxygen concentration, and salinity. While Hercules was designed to support archaeology and other scientific missions, in many respects it is a fairly conventional "work class" ROV, very like those used to service oil rigs and underwater pipelines. It is comprised of an open aluminum frame that holds most of the components. A cylindrical titanium pressure case 12 inches in diameter and 52 inches long holds most of the vehicle's electronics. Hydraulic thrusters -- propellers in fixed ducts -- control the ROV's movements. A bright yellow flotation package supports the rest of the vehicle when it is in the water, and drops the average density of Hercules to just a little less than the density of seawater. This makes Hercules just slightly buoyant, so it will float on the surface, but a small force generated by the vertical thrusters can drive the ROV up or down. The flotation package is made of "syntactic foam", composed of tiny, hollow glass balls mixed into epoxy resin. The foam is pretty heavy -- it has a density about half that of seawater -- but it can withstand the pressure exerted at a depth of 4,000 meters (more than 6,000 psi). The density of this foam is about the same density as pine or other softwood lumber. Hercules had to be designed to withstand the enormous pressure at its maximum depth. Most of the vehicle's on-board electronics are built into cylindrical titanium pressure housings. Any air exposed to the outside pressure will be compressed to one four-hundredth of its original volume, which can destroy other components in the process. To avoid this, the vehicle's electrical components that are not in pressure housings are immersed in mineral oil, which does not compress significantly under pressure, and does not conduct electricity or cause corrosion like seawater. Electric motors, transformers, electrical junction boxes, and much of the external wiring are filled with oil. Hercules also uses the same oil, driven by a hydraulic pump, to activate its arms and thrusters. Pilots aboard a support ship operate Hercules via a long fiber-optic cable that transmits operator commands, video, sensor data, and electrical power. The thrusters, commanded by the ROV pilot, move Hercules through the water. Like a helicopter, it can "fly" in any direction, but will gently float to the surface if its thrusters stop turning. Hercules is operated from a control room that is built into two standard 20-foot containers, so it can be moved onto different ships all over the world. The control room contains the computers, electronics, and video monitors which allow the ROV pilots to operate the vehicle.