The JASON Remotely Operated Vehicle System

Abstract

important scientific artcles and proved the value of manned submersible operations in .the deep sea (ref.7).1 FAMOUS was followed in rapid succession by a series of equally important scientific expeditions using manned submersibles in the Cayman Trough (ref.8), Galapagos Rift (ref.9), and East Pacific Rise (EPR) (ref.10) and on return trips to the MAR (ref.11).These subsequent efforts resulted in major new discoveries in marine science including hydrothermal vent fields and their unique benthic communties in the Galapagos Rift (ref.9) and polymetallc-sulfide deposits and "black smokers" on the EPR at 210 North (ref.10).This ten-year period from 1972 to 1981 was clearly the "decade of manned submersibles."But despite their many successes which continue to this day (ref.12), manned submersibles have certain inherent technological characteristics that wil always limit their ultimate efficiency.An average dive on ALVIN, for example, results in three to four hours of actual bottom time (ref.13).Manned presence also requires the submersible to be large and expensive for reasons of life support and safety and only one or two scientists can participate on each dive.A typical vehicle weighing twenty tons requires a large, expensive 'ship and sophisticated handling system.Space is also limited inside the pressure sphere which greatly reduces the supporting documentation a scientist can carry as well as instrumentation for data acquisition and analysis.An average manned submersible expedition lasts 21 to 28 days, during which anyone scientist in the science party may make 3 to 5 dives (ref.13).In other words, three weeks to a month at sea wil result, on average, in nine to fifteen hours on the 'bottom for each participating member.Finally, it is important to point out that "manned" operations are not truly manned.Unlike the astronauts on the moon, a scientist cannot get out of the submersible and walk around on the bottom of the ocean using their hands freely to pick up samples or place instruments.An aquanaut is trapped inside the pressurized capsule, must look through a small window to see the outside world, and must use a mechanical arm to pick up samples or do desired manipulation.In other words, "manned" submersible operations are by definition partially "unmanned" at best.Despite all these inerent limitations, the scientific community made the decision in the late 1970's and throughout the 1980's that taking a scientist to the bottom of the ocean was, worth the expense given the unique contribution they could make in-situ.Ths decision proved wise and resulted in some of the most important discoveries ever made by marine scientists seeking to better understand the geology, geophysics, biology, and chemistry of the deep sea (ref.7, 9~ 10, 14).By the early 1980's, however, new technological innovations made it possible to develop a new exploration vehicle system that would be neither manned nor unmanned but'a hybrid of the two (Le.,a"teleoperated"system).A teleoperated system permits an operator to control a vehicle from a distance by means of either a tether or acoustic link.A distributed control system permits the operator to change easily from full robotic control to manual control as well as a continous series of combinations between these two extremes (ref.15).