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Overview of Existing and Planned Assets HIGHLIGHTS This chapter · Presents the argument that the current suite of assets will limit efforts to achieve the scientific potential discussed in Chapter 2 (to support calls for changes in the number, nature, and accessibility of deep submergence assets) · Documents the strengths and weaknesses of various classes of platforms currently available (to support recommendation of a mix of assets and need for improvements of subsystems) · Describes the number, suitability, and distribution of existing assets (to support calls for expansion of available assets by improv- ing access to non-NDSF assets and adding new assets) Research efforts to gather data from the undersea world have their origins in surface ship techniques for obtaining samples from beneath the ocean's surface. It became rapidly obvious, however, that in situ observa- tion and sampling was crucial to understanding processes occurring at depth. This led the scientific community to use undersea vehicles that was developed for the military, for industry, or specifically for academic research. Three categories of undersea vehicles are now commonly used: 1. HOVs (human-occupied vehicles) are autonomous vehicles driven 43
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44 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE by a pilot, and generally with a crew of two (two scientists or one scientist and a copilot). They are equipped with sampling devices and multiple sensors. Although often augmented by video systems, they also allow di- rect observation with the human eye through viewports or a transparent acrylic sphere. The duration of a dive is limited by battery life, human endurance, and safety protocols (e.g., operation only during daylight hours), and typically does not exceed 10-12 hours, including descent and ascent. The exceptions are the Russian Mir submersibles operating on a 100-kW battery that can provide dive times in excess of 14 hours. A1- though more than 200 HOVs have been built worldwide since the late 1950s (NRC, 1996), only about 16 are used for scientific investigations worldwide. Four countries presently operate HOVs with a capability to dive more than 1,000m for scientific purposes: United States, lapan, France and Russia (Table 3-1~. 2. ROVs (remotely operated vehicles) are controlled by a pilot out- side the vehicle rather than within it. Generally the pilot works from a surface ship to which the ROV is tethered by an "umbilical cord." This umbilical cable provides electrical power and control commands to the ROV and transmits sensor and feedback data to the pilot. ROVs are often operated from a sophisticated control room where monitors display the images of the seafloor or water column in real time. The advantage of the control room is that it allows a number of scientists or engineers to dis- cuss the data in real time and make collective decisions about the opera- tions. Because of the umbilical cable, there is no energy limitation and the vehicle potentially can remain below the surface for days. The umbilical cord, however, represents a constraint on operations because the range of the vehicle with respect to the ship cannot exceed a few hundred meters (some fraction of the length of the cable). The ship must therefore antici- pate the movements of the vehicle, which requires a ship equipped with a dynamic positioning system. Moreover, the presence of a tether limits maneuverability and can introduce entanglement problems in rugged ter- rain such as hydrothermal fields with high chimney structures (up to sev- eral tens of meters). There are a large variety of ROVs with various sizes and depth capabilities. ROVs are used routinely for offshore oil and gas operations for the support of subsea cable laying, retrieval, and repair. ROVs also have been developed or purchased for scientific purposes in many countries. 3. AUVs (autonomous underwater vehicles) are unoccupied submersibles without tethers; all power is supplied by onboard energy systems. They are generally fitted for specific tasks, and their mission is programmed into the AUV before launch. Remote control communica- tion, although possible with acoustic transmissions, is not practical in the absence of a cable. Some AUVs can operate as hybrid ROV-AUV systems
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OVERVIEW OF EXISTING AND PLANNED ASSETS TABLE 3-1 Major Existing HOVs 45 Maximum Operating HOV Operator Depth (m) Shinkai 6500 Japan Marine Science and Technology Center 6,500 QAMSTEC) Mir I and II P.P. Shirshov Institute of Oceanology, Russian 6,000 Academy of Sciences Nautile French Research Institute for Exploitation of the Sea 6,000 (IFREMER) Alvin National Deep Submergence Facility (NDSF), Woods 4,500 Hole Oceanographic Institution (WHOI), United States Cyanua IFREMER, France 3,000 Shinkai 2000a JAMSTEC 2,000 Pisces IV Hawaii Undersea Research Laboratory (HURL), 2,170 United States Pisces V HURL, United States 2,090 Johnson Sea-Link Harbor Branch Oceanographic Institution (HBOI), 1,000 I and II United States Deep Rover Nuytco Research Ltd., Canada 900 Remora 2000a Comex, France 610 JAGO Max Planck Institute, Germany 400 DeepWorker 2000 Nuytco Research Ltd., Canada 600 Delta Delta Oceanographics,United States 370 Clelia HBOI, United States 300 aNot currently in use. Japan Marine Science and Technology Center's AUV Urashima) through use of a single microfiber-optic cable. For nonhybrid AUV systems, the data are recorded and recovered with the vehicle, while a subset can be sent to the support ship via acoustic transmission. A large variety of AUVs are available, and they are used for military, industrial, or scientific purposes.
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46 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE ROVs with an extremely long cable (e.g., ROV Kaiko) typically require a dedicated mother ship with a dynamic positioning system and a suit- able handling system to launch and recover these vehicles. According to the National Deep Submergence Facility (NDSF), the daily rates of opera- tion for the Alvin and Jason II are similar, and both HOVs and ROVs re- quire a technical team of three to six individuals (this is similar to running a modern working class ROV, which requires a minimum of three people for 12-hour operations). If there are special tools, a fourth person may be needed. Twenty-four-hour operations require six-person crews. Rental rates for commercial ROVs vary considerably depending on the type of system, how it will be used, and the skill level and experience of the crew. Each mission is different, and therefore a direct comparison of costs to run commercial and NDSF assets is not straightforward. For a given cruise duration, ROVs actually spend more time on the seafloor or water col- umn than HOVs because they do not have to return to the ship every day. The operation of an AUV typically requires three to four people. HUMAN-OCCUPIED VEHICLES Although many HOV submersibles are capable of providing greater scientific access to the deep ocean, there is some question about whether they are being used to their fullest extent. The following are brief descrip- tions of some of the most frequently used and best-known deep submer- gence vehicles. Although some of these vehicles are currently available for users outside their home institutions, a comparison of safety standards with those of U.S. NDSF vehicles was outside the scope of this study. Scientists proposing to use non-NDSF deep submergence assets are en- couraged to review those safety issues. Alvin The Alvin is the only NDSF HOV and is operated by Woods Hole Oceanographic Institution (WHOI). It is owned by the U.S. Navy and is usually contracted through funding by the National Science Foundation (NSF). Alvin has one pilot with room for two scientific observers and is rated to a maximum operating depth of 4,500m (see Figure 2-1~. Alvin is fitted with two manipulator arms, and four externally mounted video cameras; it has both quartz iodide and metal halide lights, and has a front sample basket that can hold 454 kg (1,000 pounds in air) of specimens and gear. At present, Alvin is scheduled at 100 percent of her available time, which is limited by a maintenance schedule. As shown in Figure 3-1, the number of dives Alvin conducts each year varies somewhat, but it rou-
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48 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE finely averages between 100 and 175 dives each year. Dive schedules are dependent on overhauls and maintenance, although some potential time is lost by transiting to various dive locations. Arrangements for use of Alvin are made through the University-National Oceanographic Labo- ratory System (UNOLS) NDSF. Shinkai 2000 The Shinkai 2000 is operated by the Japan Marine Science and Tech- nology Center (JAMSTEC) for use by JAMSTEC scientists. At present there is no funding by lAMSTEC for this vehicle, which is currently in storage but is considered fully capable and ready to dive on very short notice. Use of the Shinkai 2000 submersible by lAMSTEC or outside par- ties would require funding a full year of operations. This has resulted in little or no interest by either lAMSTEC or outside parties in making use of this vehicle. Shinkai 6500 With the Shinkai 2000 in extended dock, lAMSTEC now operates only one occupied submersible, the Shinkai 6500. This vehicle has a tita- nium hull and a maximum operating depth of 6,500m, making her ca- pable of visiting approximately 98 percent of the world's ocean volume. She was built in 1989, requires a pilot and a copilot, and has room for a single scientific observer. Two manipulator arms and one forward-look- ing and two forward and down looking viewports provide the pilots and observer with partially overlapping fields of view. The seafloor off the Japanese coast is a collection of subducting lithospheric plates, an 8,000m trench, and an abyssal ocean bed with accumulated sediments, all of which provide a multitude of scientific research possibilities close to Shinkai 6500'S home port. Specifications for the submersible include a titanium pressure hull, a weight of 25.8 tons in air, a maximum operating depth of 6,500m, a maximum speed of 2.5 knots, and two three-chip CCD (charge-crupled device) video cameras, one fixed to the front of the vehicle and the sec- ond on a pan-tilt unit between the pilot's and observer's viewing win- dows. The Shinkai 6500 iS outfitted with seven lights: four 500-W halo- gen lamps, two 1,000-W halogen lamps, and one 250-W thallium lamp. Video footage is recorded onto digital video (DV)-Cam videotapes. There are two manipulator arms (7 degrees of freedom) and two large movable sample baskets. Payload weight is 200 kg in air. Regular dives last up to 9 hours, with life support available for 129 hours.
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OVERVIEW OF EXISTING AND PLANNED ASSETS 49 Currently the Shinkai 6500 dives approximately 60 to 90 days per year due to an extremely rigorous maintenance schedule, which is nec- essary given the extreme depths to which she dives. Although arrange- ments between lAMSTEC and non-lAMSTEC co-principal investigators (PIs) do occur, they are not the norm. For these reasons, use of the Shinkai's is not considered a feasible option when NDSF assets cannot be used. Johnson Sea-Links I and II The use Johnson Sea-Links I and II (}SLs) are owned and operated by Harbor Branch Oceanographic Institution (HBOI). The ISLE (see Plate lb and Figure 2-1) are classed and certified to a maximum operating depth of 914.4 m by the American Bureau of Shipping (ABS). The forward 5-inch- thick acrylic sphere accommodates the pilot and a scientist at 1 atmo- sphere (atm) and allows panoramic visibility. A second crew member and another scientist occupy the aft observation chamber where a video moni- tor and side viewports provide forward and side observations. The evolu- tion of specialized equipment such as manipulator arms, suction devices, and rotary plankton samplers has made it possible to accomplish almost any work from within the submersibles that could once be done only by divers in shallower depths. The AL submersibles are further outfitted with active SONAR (sound navigation and imaging), laser-aimed, still and broadcast-quality video cameras and HBOI-developed xenon arc lights. AL I and II have been in operation since 1971 and 1975, and have com- pleted 4,545 and 3,400 dives, respectively. Typical applications for the ISLE include benthic and midwater observations; photo or video documenta- tion and collection of organisms; punch and box coring; search and recov- ery; bottom surveys; photogrammetric surveys; archaeological site docu- mentation and recovery; and environmental impact studies. The combination of panoramic visibility, a variable ballast system, and a vari- ety of collection tools make the ISLE especially well-suited for midwater studies. Although HBOI researchers and collaborators from other institutions are the primary users of the ISLE, the vehicles are available for other users. In fact, a significant portion of the research conducted by the ISLE has been funded by agencies such as the National Science Foundation (NSF), National Oceanic and Atmospheric Administration (NOAA), and Office of Naval Research (ONR). NOAA and ONR provide support for AL op- erations; although NSF supports the research and ship operations con- ducted using the ISLE, it supports operation only of the NDSF HOV (Alvin). Use of the ISLE is therefore a prospective option when NDSF as- sets are not available or appropriate.
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50 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE Nautile The French Research Institute for Exploitation of the Sea (IFREMER) submersible Cyana has been permanently retired. The sub was built mostly for observation and has a depth capability of 3,000m. The suite of scientific missions has shifted from observation to sampling and experi- ments, and Cyana is not well suited for that type of activity. An improve- ment over Cyana was Nautile. Like Cyana, Nautile allowed a single ob- server and required a pilot and copilot. Nautile has a depth capability of 6,000m, two manipulators, a large sampling basket, and an equipment payload of 200 kg. The two major portholes (for the pilot and the scientist) are located in front of the vehicle and their field of view overlap, which makes sampling operations easier. Nautile recently underwent a refit that resulted in major improvements of the navigation and camera systems. It is occasionally used for nonscientific purposes such as filming historical shipwrecks, salvage work on the Titanic, and work on the wreck of the oil tanker Prestige. The Nautile was constructed and is operated by IFREMER for its sci- entists through its operational organization GENAVIR. Proposals for cruises are evaluated at the national level by independent committees for the various scientific disciplines. IFREMER then constructs a schedule that accommodates the ranking of the proposals, the logistics of the ships, and the budget of the fleet. This schedule is approved at the national level by an independent committee. There is presently a move to evolve from an annual schedule to a multiannual schedule that would facilitate the logis- tics of the ships. Due to budget limitations, neither of the HOVs is pres- ently used to its full potential. Nautile dives only approximately six months per year. To increase the budget of the fleet, Nautile has been leased occasionally for commercial purposes. IFREMER has stated that the operational year of Nautile could be extended to other non-IFREMER scientists if adequate funding is provided, along with an appropriately equipped mother ship staffed by an IFREMER-GENAVIR team. Use of this vehicle may be an alternative when the use of Alvin is not possible. Mir I and II The Russian deep submersibles Mir I and Mir II have a depth capabil- ity of 6,000m. They operate in tandem from the large dedicated research ship Akademik Mstislav Keldysh, which employs a side-launch deployment system. The personnel spheres of these vehicles are built from managed iMaraging is a specific heat treatment process for steel that provides very high strength and durability.
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OVERVIEW OF EXISTING AND PLANNED ASSETS 51 steel rather than titanium, which allows for greater interior volume at the same outer diameter. The arrangement of viewing ports and the ergo- nomics inside the sphere of these subs are regarded by users as the best among all research HOVs. Likewise, they have a greater speed and longer underwater duration than most, if not all, comparable systems. They were built in Finland by Rauma-Repola in 1987 and are operated by the P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences. They have a demonstrated versatility and adaptability and, in addition to their research capabilities, have been utilized for film making, shipwreck survey, and tourist diving. Diving two submersibles simultaneously (they are launched and recovered about 30-40 minutes apart) provides advan- tages in terms of safety, manipulative operations, scientific observations, and lighting. The Mirs are commercially available to groups other than members of the Russian Academy of Sciences, and requests for their use are made to the Laboratory of Deep Manned Submersibles of the P.P. Shirshov Insti- tute. As with all deep submersible assets from any country, availability is often governed by the availability of the mother ship, transit time or dis- tance, and funding. Because of this, the Mirs do not have full schedules and thus are not utilized to their full potential. The Mirs, therefore, repre- sent a possible alternative for scientists that cannot make use of NDSF vehicles. REMOTELY OPERATED VEHICLES Remotely operated vehicles have improved significantly over the last decade, which has given them wider acceptance in the deep sub- mergence research community. They are capable of diving as deep, and often deeper, than HOVs, and improvements in video and camera technologies have provided a better viewing experience than older models. Commercial enterprises such as the oil and gas industry use them routinely in construction and maintenance of offshore oil plat- forms and in burying cables. Less expensive to build than HOVs, ROVs are able to perform a variety of scientific tasks that have contributed significantly to the study of oceanography. The following material de- scribes some of the deep-sea ROVs currently used for scientific pur- poses (also see Table 3-2~. Jason II and Medea The Jason II-Medea ROV system is an NDSF asset managed by WHOI. A precision multisensory imaging and sampling platform, Jason II is rated to a maximum depth of 6,500m. Medea operates with Jason II, serving to
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52 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE TABLE 3-2 Deep-Sea ROVs Used for Scientific Purposes Maximum Operating HOV Operator Depth (m) Kaikoa JAMSTEC, Japan 11,000 UROV7K JAMSTEC, Japan 7,000 Jason II-Medea WHOI, United States 6,500 Victor 6000 IFREMER 7,000 ISIS Southampton Oceanography Centre, U.K. 6,000 ATV Scripps Institution of Oceanography 6,000 Ropos Tiburon Canadian Scientific Submersible Facility, Sidney, B.C., 5,000 Canada Monterey Bay Aquarium Research Institute (MBARI), 4,000 United States Hyper Dolphin JAMSTEC, Japan HYSUB 75-3000 Ventana MBARI, United States 3,000 1,850 aThe vehicle subunit of the ROV Kaiko system was lost on a cruise In May 2003. provide lighting as well as tether management, which reduces the amount of surface motion influence on the Jason II's tether. Both are equipped with high-quality cameras and lighting systems. The system also has several acoustic sensors, a forward drawer, and two swing arms. It has the capac- ity for high-speed digital link-up and sophisticated sensors to allow a high degree of maneuverability in tight spaces. Like the Alvin, Jason II-Medea is an NDSF asset, the use of which must be requested from the UNOLS NDSF. Jason II is usually contracted through funding by NSF, NOAA, or the Navy. At present, Jason II is sched- uled at 100 percent of the available time and, as is discussed below, is projected to be heavily oversubscribed in 2004. Ventana The Monterey Bay Aquarium Research Institute (MBARI) in Moss Landing, California, operates the scientific ROV Ventana, which is a work-
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OVERVIEW OF EXISTING AND PLANNED ASSETS 53 class system built by ISE in Canada and extensively modified for science. It has a depth range of 1,850m and a broad suite of instrumentation, sam- plers, and tools, including high-definition television (HDTV) and modu- lar tool sleds for benthic and midwater work, as well as for rock drilling, vibra-coring, and cable laying. First deployed in 1988, Ventana has made nearly 2,500 working dives and has more than 7,000 hours underwater. It is currently operated chiefly on day cruises out of Moss Landing Harbor. The surface support ship employs a line-of-sight microwave link to shore through which it transmits a live video feed from the ROV to the home laboratory and to the Monterey Bay Aquarium for interactive feedback and outreach. The Ventana has a full schedule each year. It is used principally by re- searchers at MBARI and its collaborators, which may include co-PIs and scientists from other institutions. MBARI makes 30 days available each year, through the West Coast NOAA Undersea Research Program (NURP) Cen- ter at the University of Alaska, for ROV access by non-MBARI scientists. Tiburon Tiburon is a second-generation research ROV built at MBARI, with a 4,000-m-depth range. It employs a number of innovative design charac- teristics that reflect the needs of researchers. These include a variable bal- last system that allows the vehicle to be trimmed repeatedly to neutral buoyancy, a camera and light system that slaves cameras and lights to the focal point of a master camera, and a quiet electrical propulsion system. Like Ventana, the Tiburon has modular tool sleds and can carry a broad range of work packages. Tiburon is deployed through a moon pool in the center of a SWATH (small waterplane area twin hull) vessel, which pro- vides a very stable operational platform in advanced sea states. The Tiburon's availability and access are the same as the Ventana's. Like the Ventana, Tiburon is used principally by researchers at MBARI and its col- laborators, which may include co-PIs and scientists from other institu- tions. The R/V Western Flyer is the support vessel for ROV Tiburon and is utilized primarily for extended operations. Ropos Ropos is a 5,000-m ROV available on a for-lease basis and operated by the Canadian Scientific Submersible Facility (CSSF), a not-for-profit pri- vate sector corporation. This ROV is a "fly-away" system that has been deployed successfully from a number of ships of opportunity. For deep operations, Ropos is connected to a cage by a 300-m flying tether. The cage and ROV are launched and recovered as a unit, but at depth the
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66 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE in this report are above and beyond any capabilities called for in those two reports. This report does not revisit the scientific justification in detail here; the committee concurs with recommendations put forward in both reports. Specifically, the NRC (2003a) report concluded that ROVs would be the primary deep submergence vehicles needed by the OOI and that about two ship-years of ROV time would be required annually by the OOI. It recom- mended that when the OOI is implemented, NSF should provide submer- gence support for it by adding a second deepwater ROV to the NDSF pool and provide academic access to a third ROV that is not necessarily within the NDSF. This study assumes that these recommendations will be followed when the investment is made in the OOI. In other words, recommendations made in this current study for the mix of deep submergence assets required for future scientific needs, exclusive of the OOI, are independent of, and in addition to, those made in the NRC (2003a) study on implementing an ocean observatory network. Pertinent to the NRC (2003a) study, key findings and recommenda- tions: "ROVs are anticipated to be the work-horses of deep-ocean observa- tories. ROV resources will be needed for installation of seafloor observato- ries, connecting moorings to seafloor junction boxes, installing experiments, and servicing or repairing instruments and network equipment on the sea- floor. Their durability on the bottom, heavy-lift capability, and high avail- able power make them indispensable assets for observatory operations.... Human-occupied vehicles (HOVs) are not likely to play a major role in rou- tine observatory installation and servicing due to their lack of power, short dive duration, lack of heavy-lift capability, avoidance of suspended cables, and limited communication capabilities to the surface. However, because HOVs are untethered to the surface and thus highly maneuverable, they may be useful in some instances for conducting scientific investigations around observatory sites, and for initially establishing experiments and lo- cating sensors in areas of complex topography such as a hydrothermal vent field." The improved Alvin replacement recommended in this study can prob- ably accommodate the modest observatory needs for HOVs. It must be emphasized, however, that the additional deepwater ROV recommended in this study is in addition to the ROVs needed for virtual full-time sup- port of the OOI. DEMAND For the next two years (2004 and 2005), funding and pending cruises in the United States demonstrate the new interest of the scientific commu- nity in using Jason II for different reasons. First, the community is con- vinced of the efficiency of this vehicle to conduct the scientific programs.
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OVERVIEW OF EXISTING AND PLANNED ASSETS 67 Second, it increases the depth range and therefore opens new scientific targets. Finally, location maps clearly show that it breaks the yo-yo pat- tern that the Alvin still experiences. For the first time, the demand on Jason II exceeds the demand on Alvin. CAPABILITIES NEEDED TO REACH SCIENCE GOALS The use of deep-sea HOVs and ROVs allows real-time direct obser- vation (either in person or remotely), mapping, in situ sampling, and experimentation, along with monitoring of the seafloor and water col- umn, and their associated biospheres, as well as their physical and chemical attributes. It is an understatement to say that a number of ex- citing discoveries would never have occurred if these facilities had not been available. The 40 years of deep submergence science clearly show a trend in initial exploration to repeat measurements and experimenta- tion. A variety of tools have been developed around the vehicles: sam- pling devices, and physical, chemical, and biological sensors. The image recording capacities have improved dramatically with new camera sys- tems and lights. Currently, it is obvious that the scientific community needs to have access to a full range of assets that can be used in various combinations. HOVs, ROVs, and AUVs each have their own advantages depending on the scientific problem that is to be addressed and the ap- propriate research protocol. While ROVs and AUVs will undoubtedly become more sophisticated, which may supplant the need for human scientists to carry out deep ocean research directly in many instances, the added value of human perspectives will remain significant. As tech- nology improves to link human eye movements (rather than the hands) directly to automated camera control, it will ensure that HOV and HOV- ROV hybrid systems are superior to ROV systems for a wide range of applications well into the future. Viewing and Documenting The primary goal that justifies the use of deep-sea submersible for geologists is to be able to actually view the study site. It is only the combi- nation of mapping, viewing the terrains, and sampling that allows the construction of geological maps that portray the character and extent of lithologic units, as well as their spatial relationships. Viewing also allows the description and measurement of tectonic features, such as orientation of fissures and fault planes, the nature of tectonized surfaces, and easier location of the distribution of hot vents and cold seeps with respect to tectonic activity. This is the normal, necessary approach on land, and only the use of submersibles makes it possible at the seafloor. For biologists,
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68 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE viewing gives them the ability to identify animals through visual cues, observe their behavior, quantify them, relate their distributions to envi- ronmental parameters, and sample an undamaged state. With HOVs and ROVs the ability to view the environment outside the vehicle is essential to conduct a dive; real-time decisions are made on the basis of what is seen. Viewing is achieved directly with the human eye and video cameras in HOVs and through a combination of video cameras with ROVs. In both cases, light is required to illuminate the field of view or water mass, which is completely dark at depths greater than a few hundred meters. Red light illumination has proved invaluable for observ- ing animal behavior unmodified by the effects of light, since most deep- sea animals are sensitive only to light in the blue-green end of the spec- trum. With an HOV the human eye has several advantages over cameras. This is particularly true when the lights are extinguished to observe biolu- minescence. Although intensified cameras are much improved over the low-resolution, high-noise, long-lag-time system in use a few years ago, there is nothing better than the dark-adapted human eye for observing in low-light underwater conditions. The human eye also has many advan- tages with the lights turned on. For example, even if the portholes are small because of the pressure, the effective field of view using the human eye is much wider because it can easily follow and focus on objects out- side the HOV. This is especially true in the midwater zone where animals move in three-dimensional space, often along different vectors to the movement of the submersible. In order to correctly identify, quantify, and record the behavior of midwater animals, an imaging system must be able to focus rapidly on multiple targets in succession in a three-dimensional space while keeping peripheral vision open to identify alternate targets for subsequent or simultaneous visualization. The major drawback to the human eye is that it does not leave a permanent record for later referral other than that which can be written down or recorded as an audio signal. It also does not allow sharing of visual information with other specialists or the public directly as a video stream would, and numerical data cannot be embedded and synchronized with events efficiently. External cameras on pan-tilt mechanisms can follow moving organisms, but the movement is not instantaneous and focusing is also not as rapid as with the human eye. Several experts commented at open sessions of the Committee on Future Needs in Deep Submergence Science that some of the discoveries made while diving might never have happened using an ROV. The lack of three-dimensional vision on video screens presents problems with the interpretation of the images collected by an ROV. This will certainly be improved in the future with stereo viewing or three-dimensional visual- ization. The configuration of portholes in Alvin, however, should be im- proved, if at all possible. In the present setup there is minimal overlap
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OVERVIEW OF EXISTING AND PLANNED ASSETS 69 between the fields of view of the pilot and the two observers. This makes interaction difficult particularly during manipulations. At this point it seems that the interpretation of video images on moni- tors is more straightforward for scientists with HOV dive experience. On the other hand, the monitors in a control room can be watched in real time by a group of scientists who can share their experience. With satellite com- munications advice can even be requested in real time from specialists in their office on land. lAMSTEC uses a single fiber-optic cable communica- tion system in the battery-powered deep-diving submersible platforms UROV7K and AUV Urashima. Such a system could also be incorporated into any HOV platform, expanding the number of scientists viewing the deep ocean when desired. Both HOVs and ROVs record images on video and still cameras. The quantity of data collected tends to increase drastically and consequently raises the question of storage, archiving, and accessibility. Database sys- tems for the storage of nonnumerical data have been developed at insti- tutes such as the Monterey Bay Aquarium Research Institute. Because of the lack of real-time communication, AUVs are suited only for preprogrammed systematic surveys. The optical images collected al- low the construction of image mosaics, which are of great value in docu- menting an area at a local scale. Sampling Sampling in situ, in a well-characterized environment is a major ad- vantage of submersibles. For geologists, the value of collecting a rock from a previously defined and characterized unit is enormous, compared to dredging loose rocks over a distance of several tens to hundreds of meters. The collection of hydrothermal fluids from vents requires placing a sy- ringe or a sampling tube into a hydrothermal conduit that may not exceed a few centimeters in diameter. Delicate biological samples can be collected only with manipulators and must be stored in dedicated boxes immedi- ately. Sampling of some of the fragile gelatinous animals from the midwater requires special tools, and because a failed sampling attempt can destroy the organism that is being sampled, depth perception is ex- tremely important. A trained ROV pilot can use multiple cameras set at different angles to visualize a three-dimensional space, but because this system is not intuitive and sampling efficiency is usually less than with HOVs, the precision of the sampling drastically influences the quality of the sample. The sampling of biological specimens also benefits from a characterization of the environment, that is, the local temperature and fluid chemistry. Both HOVs and ROVs are equipped with precision manipulators that
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70 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE are operated by the pilot either on the HOV or from the control room on the ship. They allow the pilot to collect rocks from the seafloor (if they are reasonably loose) and also to operate a variety of sampling tools attached to the vehicles, such as water bottles, pumps, slurp guns, sediment corers, rocks drills, and so on. The samples collected are stored directly in a bas- ket or in specially designed containers. This is crucial for an efficient sam- pling program, and both types of vehicles have been used successfuly during a large number of cruises. In practice, however, manipulations seem to be less efficient through remote control with an ROV because of the lack of three-dimensional vision on video monitors. This is compen- sated for by the absence of a limitation on the time spent over the seafloor with an ROV. The depth perception provided by direct observation also gives the scientist a better understanding of the context in which samples or data were collected. Another difference between HOVs and ROVs comes from the com- bined payload and duration of the dive. Systematic sampling programs can offer unique challenges to deep-water operations. These sampling programs can rapidly meet the weight limit as the collection basket and containers are filled. Moreover, biological samples, displaced from their environment, have to be recovered as soon as possible to avoid deteriora- tion. With HOVs the total duration of a dive rarely exceeds 8 to 10 hours, and the time actually spent over the seafloor is typically 6 to 8 hours. The accumulation of samples collected during this time can normally be ac- commodated. The samples are recovered every day with the vehicle and are readily accessible for possible experiments onboard. With ROVs the duration of the dive may reach several days. In that case the upper weight limit is reached rapidly and continued sampling requires the use of an elevator. This is essentially a big container with drawers, which is launched directly from the ship and lands on the seafloor. The drawers are filled with samples using the manipulators, and then a release system sends the elevator back to the surface where it is recovered by the ship. Although it is an efficient system, the use of an elevator is time-consum- ing because the ship and vehicle are committed during the launch and recovery. In acceptable sea states however, the elevators can be recovered by a zodiac or similar small boat. If necessary, an elevator can also be used with an HOV, although no such system currently exists for recovery of samples from within the water column. Because of the lack of real-time communication and limited payload and availability of energy, AUVs are not appropriate for sampling with manipulators. Simple sampling procedures can be programmed, such as the filling of water bottles at regular time intervals, but AUVs are not likely to become good sampling vehicles in the near future.
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OVERVIEW OF EXISTING AND PLANNED ASSETS Platform Stability 71 Stability of submersible platforms relative to position above the bot- tom or within a given water mass is best attained using a variable ballast system. Such systems can be installed on any platform, including HOVs, ROVs and AUVs. They ensure greater visibility and more efficient use of dive time by making the submersible neutrally buoyant at depth without the use of thrusters. This minimizes sediment or flow field disturbance; enables fine manipulation of fragile equipment, samples, or experiments even in regions of rough topography; and allows quantification of objects on the bottom through the ability to keep a stable altitude and in the wa- ter column through being able to adjust the speed of forward movement relevant to suspended particles. Near-perfect trim to neutral buoyancy, especially with HOVs and AUVs that are completely decoupled from the surface, also permits implementation of sensitive optical experiments such as low-light-level measurements, which otherwise would be compro- mised by unwanted stimulation of bioluminescence, and holographic par- ticle velocimetry, which would be compromised by unwanted platform movement and disturbance of natural flow fields. With the notable excep- tion of the Tiburon, the current suite of scientific ROVs lacks a sufficiently robust variable ballast system to allow the ROV to become truly neutrally buoyant. Mapping and Surveying The resolution of bathymetric and geophysical surveys depends on the distance to the object. Closer distance clearly allows better resolution. For instance, faults with a trough of a few meters are not detected from surface mapping although they play a crucial role in the location of fluid vents and therefore the distribution of associated biology. Magnetization lows associ- ated with hydrothermal circulation were detected only by near-bottom sur- veying; they now provide a new tool to search for discharge zones on the seafloor. Ideally, the characterization of an area requires a combination of scales from the general picture acquired from surface mapping to detailed mapping using submersibles in selected, particularly interesting, detailed areas. For example, the detailed map of a hydrothermal field, with the loca- tion of all the vents with respect to local tectonic features, has to be placed in the general context of the ridge segment. Although HOVs have occasionally been used for specific surveys such as magnetics, in situ gravity measurements on the seafloor, or routine recording of temperature and some chemical parameters, ROVs and AUVs are clearly better suited for that type of work. Mapping and sur- veying typically include bathymetry, sonar imaging, wide-angle optical .
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72 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE imaging, magnetics, temperature, and salinity. More sophisticated sen- sors can also be attached, such as nephelometers to record the turbidity of water or manganese sniffers to detect chemical anomalies in the water column. Methane sensors, still under development, will be useful tools to locate regions of active serpentinization or cold seeps in margin environ- ments. Surveys can be conducted at various heights above the seafloor depending on the scientific objectives. Typically, a bathymetric map will have a horizontal resolution of a few meters if collected at 20 to 30 m, and <1 m if collected 8 to 10 m above the seafloor. ROVs have the advantage over AUV systems of returning data to the ship in real time, allowing the operators to make decisions on the vehicle track. This capability is essential to follow structures such as ac- tive faults or plumes in the water column. The ROV is linked to the ship however, and therefore the ship time is completely devoted to the sur- vey. AUVs can be programmed to conduct a systematic survey and have the advantage of being completely autonomous. Once launched, they conduct their own program independently while the ship can be used for other purposes. Experiments and Time-Series Investigations Studies of processes and the sampling that occurs at dynamic inter- faces, such as hydrothermal plumes (including their propagation and mix- ing along isopycnals), cold seeps, benthic boundary layers, or seafloor gas hydrates, are best done by submersibles. The intricacies involved in mea- suring the physical, chemical, and biological properties, and especially collecting samples, from these few-centimeter to millimeter-thick bound- aries require specially designed tools that must be handled with sophisti- cated submersible manipulators. In addition, conducting challenging in situ interactive perturbation experiments and observing the responses to them, including how fast they return to their "steady state," would en- hance our understanding of how these systems respond to natural envi- ronmental perturbations. The development and testing of new and novel tools for key in situ measurements, such as instruments for measuring pH and dissolved sul- fide content of pristine hydrothermal fluids, or using nuclear magnetic resonance (NMR) to document the growth habit of methane hydrate in sediments, its relationship to hydraulic permeability, and the subsequent impact on slope stability will require frequent access to various submers- ible vehicles. On the other hand, the progression from spatial exploration in ocean sciences toward temporal understanding of active processes has played a significant role in the history of the utilization of deep submergence assets,
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OVERVIEW OF EXISTING AND PLANNED ASSETS 73 both international and national. This has been manifested in a trend toward repeat visits at selected sites for time-series sampling of active processes, with irregular sampling intervals owing to the complexities of the scientific proposal and to ship and submersible scheduling procedures. This trend has contributed to the development of the OOI and may result in the estab- lishment of long-term observatories at a few of these sites. Prime examples are the time-series investigations of hydrothermal, magmatic, tectonic pro- cesses at representative ridge-crest sites, some of which are now designated as RIDGE 2000 "Intensive Studies" sites. A similar theoretical and practical approach is emerging in deep submergence investigations of active pro- cesses in other benthic environments, for example, subduction settings and sites of significant gas hydrate accumulations. The diverse scientific goals and the large depth range in margins from slopes to trenches, and in pelagic environments from ridges to basins, require an appropriate array of ROVs, HOVs, and AUVs, from shallow depths to ~7,000m, to reach most trenches. In convergent margins with deep trenches (water depths >4,000m), ROVs that are coordinated with AUVs currently seem preferable because of the limited bottom time pro- vided by HOVs at such depth. Some areas, however, have sites and seeps with communities of organisms that would benefit from direct observa- tion and delicate sampling, which may necessitate HOV use. Future op- portunities and benefits to interface with moored instrumented observa- tories and with instrumented boreholes, for basic scientific objectives and novel experiments, will have to be considered when new vehicles are de- signed. To date, most of the data downloading from monitoring instru- ments in boreholes, as well as some new instrument deployments, has been carried out with submersibles. The ability to respond rapidly to significant transient events such as large earthquakes, landslides, tsunamis, volcanic eruptions, phytoplankton blooms, eddy formations, and transient upwelling events, and to observe, sample, and interact at the sites of these events, is essential. These events are an integral part of the Earth energy cycle, which involves production, transport, recycling, the aging and subduction of the oceanic crust, and the origin of continents. Outreach Deep-sea exploration and discovery are inherently exciting and in many respects they are ideal topics to share with the public. The means for shar- ing images and data and for real-time participation in deep-sea research activities are readily available. A microwave link from surface vessels to the shore allows visitors at the Monterey Bay Aquarium each day to interact with research scientists via live video broadcast from deep-working ROVs.
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74 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE Likewise, the lason Project, the BBC (British Broadcasting Corporation), and lAMSTEC have used satellite links to carry ROV-generated video live to distant viewers. With ROVs the transmission of information and images is a fundamental aspect of their operation, connecting not only to pilots and scientists topside but also to students and the public. Until recently, live transmission from HOVs at depth was limited chiefly to through-water acoustics with a bandwidth too narrow for any- thing but voice and position data, and low-resolution frame grab images. The principal problem with acoustic transmission to the surface is stratifi- cation of the water column. One solution is to transmit to an acoustic re- ceiver (modem) at depth that is connected by wire or optical fiber to the surface. Even more promising is the use of an optical fiber that links the HOV to the surface. This fiber would provide for a direct, high-band- width link to the surface without the problems of acoustic transmission, and with reduced drag and handling problems compared to thicker ROV tethers. High-bandwidth communications from HOVs will improve their sci- entific productivity by involving many more researchers in the real-time experience, just as ROVs do. Similarly, AUVs will benefit from real-time human presence in the control loop. With both kinds of vehicles the po- tential for outreach to the public is also greatly enhanced. These advances, coupled with rapidly evolving knowledge base systems, comprise an ex- panding wave of outreach applications involving all three classes of deep- diving vehicles. CONCLUSION Each type of deep-sea vehicle definitely has its own advantages and disadvantages. The best approach to deep submergence science involves a nested survey strategy that utilizes a combination of tools in sequence (possibly over multiple expeditions) for investigations at increasingly finer scales. For geological applications, initial reconnaissance surveys are best achieved using ship-based swath-mapping systems and tethered sur- vey vehicles (including ROVs and AUVs). After the local context is estab- lished by such surveys, detailed descriptions of specific sites or work in the water column can benefit from the direct experience afforded by the use of HOVs. Experiments and observatory work that require longer time on the seafloor and/or heavy lift capabilities on already-characterized sites are best conducted with ROVs. At present, the DSVs of NDSF, specifically Alvin and Jason, are the most widely used DSVs available to deep ocean scientists in the United States. While this demand is undoubtedly a testament to the scientific support provided by NDSF and the reliability of these platforms, it also
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OVERVIEW OF EXISTING AND PLANNED ASSETS 75 represents the growing interest in conducting research into unique and interesting processes that can best be studied through the use of deep submergence assets. As discussed earlier, recent trends in total demand for access to Alvin have stabilized to the point where Alvin is essentially fully subscribed each year (Figure 3-5~. In addition, improvements in the design of Jason II have greatly enhanced the usefulness of this ROV for deep submergence work, which has resulted in an increased demand for access to this platform. As a consequence, Jason II is now significantly oversubscribed (Figure 3-6~. Pursuit of many of the high-priority science goals discussed in Chapter 2 will be limited by both the current capabili- ties and the current capacity of NDSF assets. Continued expansion and diversification of the pool of potential users can be accommodated only by providing expanded access to needed assets.
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As discusser! in Chapter I, the National Deep Submergence Facility (NDSF) currently operates two vehicles: the HOV Alvin and the ROV Jason Il. Support for the operation of these vehicles is guaranteed by the three NDSF sponsoring agencies (NSF, NOAA, ant! the U.S. Navy). These agencies are also major supporters of research that utilizes NDSF assets. For example, in 2002, NSF and NOAA accounted for nearly 100 percent of the operational days of all NDSF platforms, with NSF generally accounting for more than 70 to 80 percent annually. This arrangement ensures consistent support for NDSF, while allowing some flexibility in the burden borne by each of the three sponsoring agencies. This, in turn, allows each agency to predict its annual contribution to NDSF funding and to develop budget mechanisms to accommodate that contnbution. The use of NDSF assets by scientists funded through NSF is covered by the funds from the Marine Operations Section of the NSF/OCE. Proposals to the NSF requesting the use of these vehicles are submitted to a number of science programs within OCE. No costs for the use of NDSF platforms are included in the budgets of these individual proposals. The cost of NDSF platform use is borne by the Marine Operations Section, rather than by individual science programs. This policy reflects the commitment made by NSF to provide actditional fiscal support needler! to undertake deep ocean research and ensures that proposals are evaluated on intrinsic scientific merit. For the most part, vehicle use is essentially guaranteed to any project that is funded by the science program to which it was submitted. Scheduling vehicle use is facilitates! in at least two ways. First' projects may be postponed to accommodate vehicle schedules. Second, one vehicle may be substituted for the other in projects where such substitution is possible. In some cases, it is simply not possible to accommodate vehicle requirements and proposals are deferrer! or even rejected on these grounds. Proposals to the NSF that request the use of non-NDSF platforms must include the platform operating costs in the proposal buclget. Should the proposal lie funded, funding for platform use must be provicled by the science program to which the proposal was submitted. As the additional cost for the use of these platforms (not including cost of support ships) can be substantial ($10,000 to $30,000 per clay of use); this aciclitional cost is widely perceived as placing such proposals at an unfair disadvantage to those requesting NDSF platforms. This lack of access to suitable assets outside the NDSF is limiting the scope of deep submergence science (UNOLS, ~ 999~. It is apparent that realizing the vision of deep ocean research described in Chapter 2 will require access to a broacter mix of more capable vehicles than is currently available through the NDSFi. Because the NDSF is funcled irrespective of vehicle use, the marginal cost (i.e., the cost of an additional day of operation) is zero. In contrast, the marginal cost of tile use of non-NDSF assets can be substantial. From a fiscal perspective, it is therefore sensible to require, when possible, that NDSF assets be used in favor of non-NDSF assets. in the absence of additional funds, excess demand for NDSF assets can be managed by a combination of asset substitution (ROV for HOV or vise versa), schecluling, and, if necessary, proposal rejection. If additional funds were to be ma(le available, then excess demand can also be addressed by leasing non-NDSF assets. There appear to be situations, however, in which deep submergence scientific goals cannot be met by NDSF assets, but Carl be met by non-Nl)SF assets. Moreover, ~ The submersibles used to support deep ocean research are singular to those discussed in two recent NRC reports, Enabling Ocean Research in the 215t Century. Implententatio,~ of a Network of Ocean Observatories and Exploration of the Seas. Voyage into the Unknown. The recommendations in this report are above and beyond any capabilities called for in those two reports 76
Representative terms from entire chapter: