Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 9
1 Introduction HIGHLIGHTS This chapter · Introduces deep submergence science as a specific subset of ocean science (to establish its importance as well as the vagueness of the current definition of deep submergence science) · Describes the nature of assets used (to demonstrate the variety and distribution of platforms available; i.e., the "mix" of technology) · Discusses the nature, role, and organization of the National Deep Submergence Facility (to establish how its "management" can foster or limit scientific inquiry) · Introduces the problem as described by the statement of task (to clarify the breadth of the task) · Describes the organization of the report (to demonstrate that a logical approach was used and to foreshadow the committee's conclusions) Major advances in the understanding of the oceans have been achieved in the last 40 years. Thanks to a combination of careful planning and serendipity, ocean scientists have revolutionized the view of life on Earth, changed understanding of global tectonic processes and the role of the oceans in climate change, uncovered lost relics of human history, and discovered hundreds of new species. 9
OCR for page 10
10 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE Much of this exciting science was made possible through the use of deep-diving submersibles (see Box 1-1, Plate la,b), including the well- known human-operated vehicle (HOV) Alvin, first launched nearly 40 years ago. Despite the excellent maintenance that has allowed Alvin to make more than 3,600 safe dives and modifications allowing it to take a pilot and two scientists to depths of 4,500m, periodic calls for its replace- ment have occurred. These calls have been prompted by a part of the ocean science community that would like more capable vehicles, defined variously, but including one with better visibility; faster transit time to and from the surface, which would result in increased bottom time; and greater depth capabilities (Brown et al., 2000~. Although significant im- provements have also been made in the design and operation of remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), and a variety of in situ remote sensing and sampling instruments, the deepest part of the water column and bottom remains just beyond the reach of science. The United States has been a dominant player in ocean sciences for at least 50 years. Since World War II, and throughout the Cold War, the Office of Naval Research (ONR) has been a major driver and fonder of this research. ONR financed the construction of much of the equipment and instrumentation required, including deep-diving vehicles such as Alvin, which is owned by the U.S. Navy but operated by the National Deep Submergence Facility (NDSF) as a civilian research asset. The United States is not the only nation active in the deep ocean. More than 200 human-occupied deep submergence vehicles (DSVs)~ have been built worldwide since World War II, with only a few of them dedicated to scientific research. Japan, France, and Russia all operate their own deep- diving research HOVs (the French Nautile, which descends to 6,000m; the Japanese Shinkai 6500, going to depths of 6,500m; and the Russian Mir I and Mir II, which are capable of reaching 6,000m). In addition, the U.S. Navy's Sea Cliff submersible replaced Trieste II in 1982 and was the first 6,000-m non-bathyscaph HOV. Although several U.S. entities operate submersibles at depths up to 1,000m, very few can exceed that depth and only the Alvin can dive below 2,000m. The focus of the U.S. Navy has shifted away from deep water over the last 10 years in response to geopo- litical developments that call for greater focus on littoral environments. iThe term "DSV" has traditionally been used to signify a human-occupied deep submers- ible. As the nature of these assets has diversified however, other more descriptive terms have been employed to define specific submersible types (e.g., occupied-unoccupied, re- motely operated, tethered-untethered). The currently accepted definition of DSV, and the one used in this report, connotes any deep submergence vehicle whether it is human occu- pied, remotely controlled, or autonomous in its operation.
OCR for page 11
INTRODUCTION 11 Thus, ONR has reduced its focus on, and support for, deep submergence science. DEEP SUBMERGENCE SCIENCE Deep submergence science is defined both scientifically and opera- tionally. Based on scientific criteria, the deep sea is defined as beginning
OCR for page 12
2 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE at 150 to 200m (or the lower limit of the epipelagic zone) (Marshall, 1979; Herring, 2002~. The operational definition of deep submergence has been arbitrarily set at depths greater than 1,500 to 2,000m, based primarily on the depth capabilities of Alvin and Jason II. As a result of this operational definition and funding history, Alvin, Jason II, and other assets that are part of NDSF (see Plate 2) are the only submersibles in the University- National Oceanographic Laboratory System (UNOLS) and thus eligible for National Science Foundation (NSF) support from operations funds. NSF's Ocean Sciences Division (OCE) research funding supports projects in deep submergence science at depths shallower than 1,500m (e.g., some of the RIDGE program research, deep-sea larval biology, gas hydrate re- search, and studies conducted in midwater environments), for which both NDSF and non-NDSF platforms are used. Several HOVs and ROVs are available and appropriate for work at depths shallower than 1,500m, but mechanisms for funding these assets as part of NSF/OCE research pro- posals are perceived to discriminate against their use (UNOLS, 1999~. Because deep submergence science is often conducted at depths much shallower than 1,500m, the committee has adopted the scientific defini- tion of deep sea (i.e., the area of the ocean greater than 200m) as the basis for its recommendations concerning future needs in deep submergence science. Plate 3 depicts the depths of the oceans' basins and graphically represents the areas in which Alvin is capable of diving. Chapter 2 docu- ments the diverse nature and significance of deep submergence science and discusses the geographic and water column depth ranges in which this science has to be conducted. Techniques for sampling the ocean's depths have evolved over the last century and have generally involved sending a sampling instrument to a point within the water column or to the bottom of the ocean and then retrieving it. Charles Darwin on the Beagle, using a simple dredge low- ered by a hand line, was one of the first to systematically collect samples from deepwater benthic communities. Today there are many ways of col- lecting samples from the water column as well as the bottom of the ocean, but these methods all have their limitations. Nets and dredges are apt to damage specimens, especially if they are gelatinous (e.g., jellyfish), and provide little to no context of the surrounding area from which the sample was taken. Additionally, this sampling process is difficult if not impos- sible to carry out during special events (e.g., hydrothermal vent activity) or situations that require the researcher to exercise extraordinarily fine control (e.g., capturing a fish; inserting a water chemistry sensor into the outflow from a hydrothermal vent if the probe is off by as much as 1 cm, the data will not be valid). This human dimension of submersible con- trol which includes, for example, sensory-motor skills, reflexes, prop- rioception (the sensory feedback often referred to as "muscle memory"
OCR for page 13
INTRODUCTION 13 for specific tasks), and the pilot's and scientist's ability to develop a cogni- tive map of the area in which they are working is applicable to both HOVs and ROVs. Piloting either type of vehicle demands intense concen- tration and the ability to exert fine control over the vehicle to obtain exact and specific data and samples. The scientific need to visit the deep ocean, obtain intact samples (in contrast to trawls, for example, which most often damage or destroy speci- mens), conduct experiments, and view a location in real time has spurred the development of deep submergence vehicles. Whether visiting these depths in person in an HOV or remotely with an ROV, there is a clear and legitimate scientific imperative to continue to develop those technologies that will allow visitation of the deep ocean. Deep submergence science requires a level of sophistication and a tech- nology that can withstand the immense pressures found as ocean depth increases. For humans to directly investigate depths below 300m requires the use of a 1-atmosphere (aim) chamber (i.e., the pressure within the cham- ber is 1 aim, or that found at sea level), made from glass, steel, massive cast acrylics, or titanium. These are currently the only materials strong enough to withstand the crushing weight of the sea and allow a human to pilot the vehicle with no special protection other than the vehicle itself. Remotely operated and autonomous vehicles do not require any special chamber to protect a human occupant and thus are not constrained by any life-support systems, which make them less expensive to build and certify. Conversely, an HOV has a person on the scene at depth as opposed to a relatively inex- pensive ROV equipped with sensors and cameras. The choices are expensive life-support systems to protect a person viewing the scene through a viewport, versus less expensive remote ve- hicles that have image capture systems with a human operator on the surface. Although this study does not attempt to answer the question of which system is better in all situations, the strengths and limitations of HOVs, ROVs, and AUVs are considered. It can be said, however, that although ROVs and AUVs could undoubtedly become more sophisti- cated, possibly supplanting the need for human scientists to directly carry out deep ocean research in many instances, the added value of human perspectives will remain significant. The National Deep Submergence Facility The Woods Hole Oceanographic Institution (WHOI) has operated the primary U.S. deep water research HOV, Alvin, since 1964, initially sup- ported by a mix of short-term research and engineering contracts and grants. In 1974, the "significance of maintaining a core deep submergence operational team was recognized by ONR, NOAA [the National Oceanic
OCR for page 14
4 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE and Atmospheric Administration] and NSF . . . when they established the National Deep Submergence Facility (NDSF) at WHOI and formulated a Memorandum of Agreement (MOA) to share the operating costs of the facility" (UNOLS, 1994~. This agreement was later revised to provide a safety net of minimum facility funding to maintain the core capability if research funding for use of the capability dropped too low. Three years before the formation of the NDSF, UNOLS was estab- lished, with assistance from NSF and ONR, to coordinate U.S. oceano- graphic research ship schedules and facilities. The 1972 UNOLS charter includes provisions for national oceanographic facilities, of which NDSF is a prime example. Consequently, a standing committee of UNOLS, the DEep Submergence Science Committee (DESSC) currently has primary science community advisory responsibilities for the NDSF. UNOLS also coordinates the scheduling of support ships required for submergence operations. In sum, the NDSF was initially formed by MOA among the three primary deep submergence funding agencies, and it also has clear formal links within UNOLS. The vast majority of NDSF vehicle time is funded by NSF/OCE, NOAA's National Undersea Research Program (NURP), and activities of NOAA's Office of Ocean Exploration. Among these programs, NSF/OCE accounts for nearly 80 percent of NDSF ve- hicle operation days. Deep Submergence Vehicles Human-Occupied Vehicles The Alvin, NDSF's only operating HOV, is a three-person vehicle (one pilot and two scientific observers) capable of diving to 4,500m and re- maining submerged for 10 hours under normal conditions and up to 72 hours on emergency power. The typical dive profile for Alvin is to leave the sea surface by allowing water to enter the main ballast tanks and liter- ally sink under her own weight to the desired depth, usually the ocean bottom. She carries steel plates that make her negatively buoyant for the descent, and some of these are released when the desired dive depth is reached, resulting in neutral buoyancy. The remaining plates are carried throughout the dive and are dropped to obtain positive buoyancy for re- turn to the surface. Once Alvin achieves neutral buoyancy at a desired depth, the variable ballast system allows adjustment of the vehicle's weight by plus or minus 250 pounds for vertical excursions between dif- ferent operating depths, usually limited to a 1,000-m-depth range due to time and battery power constraints. Observations are made through three small viewports (one in front and one on each side), as well as with a number of video cameras coupled to multiple in-hull monitors. The Alvin
OCR for page 15
INTRODUCTION 15 also has a viewport on the bottom that is no longer used for viewing. However, it is equipped with a sensor to ensure that the acrylic port mate- rial does not melt when maneuvering around hot vents. In addition to a pair of manipulator arms, various scientific payloads may be attached to the front of Alvin for collecting samples and performing experiments. The greatest drawbacks to the Alvin are (1) the visibility is limited (viewports are small and not optimally placed for many viewing requirements); (2) the sphere is cramped (observers and pilots must squeeze into awkward positions in order to share available space not occupied by internal sys- tem components); and (3) the lead-acid battery energy source can result in power-related dive limitations. Remotely Operated Vehicles ROVs are unoccupied, tethered submersibles with an umbilical cable that runs from the pilot (either onboard a mother ship, on land, or even on an HOV) to the ROV. In the United States, the Navy first developed this technology. Major commercial use of ROVs began with the development of the North Sea offshore oil and gas industry in the mid-1970s. The umbilical cable carries power, pilot control input, and feedback from sensors and video cameras. Because a wireless signal quickly fades, reflects, and is otherwise attenuated under water, the only reliable means of accurately controlling a remote underwater vehicle is through an umbilical cable. While increased bandwidth in acoustic communications and im- proved task-level control have made remote control of untethered remote vehicles a possibility in the future (NRC, 1996), this technology will likely not include video feed, and thus not provide high-level feedback, reducing the applications for wireless control. Typically, an ROV will have cameras, video transmitted live to the pilot to aid in navigation, high-intensity lights, thrusters for control, manipulators, and a basket or platform for mounting equipment. The operation and control room accommodates several scien- tists that view the images and interact, in real time, with each other and with the pilot. While most ROVs have a manipulator arm, their functional- ity can vary dramatically. Some of the drawbacks of ROVs center around the problems associated with operating the vehicle remotely: (1) a cognitive mapping difficulty caused by lack of on-scene navigation; (2) the tether, which can hamper operation, especially in trenches, on walls, and in areas where entanglement may occur; (3) the need for higher-definition cameras and three-dimensional feedback that would attempt to mimic navigation in an HOV; and (4) the lack of a visual feedback mechanism comparable to the human eye, which can make precision piloting extremely difficult (e.g., navigating in reference to pycnoclines that can be seen only as a "shimmer" in the water). Furthermore, tether movement can cause turbulence, which
OCR for page 16
16 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE can set off bioluminescent displays that prohibit accurate characterization of the in situ light field. Finally, multiple organisms or particles in three- dimensional space cannot be identified or quantified while either the water mass or the DSV is moving because of focusing and pan-tilt limitations not imposed upon the human eye. Conversely, ROVs offer many benefits in- cluding reduced risk to human operators, enhanced potential for collabora- tion through real-time sharing of information with surface ship and scien- tists ashore, and virtually limitless bottom time. The best use of the vehicle, however, may differ from mission to mission depending on the needs of the principal investigator. Autonomous Underwater Vehicles An AUV is an unoccupied, untethered, usually programmable under- water vehicle that is capable of roaming the ocean depths without pilot input. Although AUVs have been under development for several decades, they have progressed more slowly than ROVs, due mainly to technologi- cal challenges associated with their power sources and control. In the 1960s and 1970s, AUV development was funded primarily by the military for missions to search large areas under ice and in deep water over long time periods (NRC, 1996~. It is only recently that applications have turned toward oceanographic science. The AUV carries instruments that map the seafloor and measure a variety of physical and chemical ocean properties; they may transmit that information via a temporary connection to the launching station, surface at intervals to upload information via satellites, or store the information to be retrieved only when the AUV is physically recovered. By virtue of their relatively small size, limited capacity for scientific payloads, and autonomous nature, AUVs do not have the range of capabilities of HOVs and ROVs. They are, however, better suited for reconnoitering large areas of the ocean that could take years to cover by other means. AUVs are thus frequently used to identify prospective regions of interest that can be ex- plored further with HOVs or ROVs. SCOPE OF THIS REPORT Over the last 20 years, a number of workshops have been held in which members of the U.S. deep submergence scientific community have discussed research priorities and assembled a "wish list" for needed new equipment (UNOLS, 1990, 1999~. High on their list is a new, state-of-the- art HOV capable of descending to 6,000m or more. Deeper-diving AUVs and ROVs are also in demand. NSF/OCE is interested in assisting this very productive segment of the ocean sciences community and asked the
OCR for page 17
INTRODUCTION 17 National Academies to carry out an independent, objective assessment of the scientific and engineering needs and opportunities before making such a large infrastructure commitment (the formal statement of task can be seen in Box 1-2~. In addition to the fiscal constraints specified in the state- ment of task, NSF/OCE indicated that capital investment will have to be made in the next two fiscal years if a new HOV is to be built during this decade (J. Yoder, National Science Foundation, Arlington, Va., written communication, 2003~. Plans are currently under way to begin implemen- tation of the research fleet upgrades recommended in a Federal Oceano- graphic Facilities Committee2 report published in December 2001 and 2The Federal Oceanographic Facilities Committee is a federal interagency committee that operates as part of the National Ocean Partnership Program created by Congress in 1997 through enactment of Public Law 201-104.
OCR for page 18
18 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE entitled Charting the Futurefor the National Academic Research Fleet: A Long Range Plan for Renewal (Federal Oceanographic Facilities Committee, Na- tional Oceanographic Partnership Program, 2001~. NSF/OCE is planning to cover the costs of constructing one Regional Class ship every two years beginning in FY 2006. The purpose of this study is to provide NSF with recommendations for its consideration regarding activities to provide infrastructure support through NDSF or other means for basic research at depth in the oceans. As such, the discussions in this report are designed to inform this ques- tion and are not intended to provide an exhaustive account of all research- related activities carried out at depth or a complete account of all the po- tential assets that exist. The discussion of assets in this report is limited, therefore, to those that establish whether adequate DSVs exist within or without the NSDF. Furthermore any recommendations made in this re- port are above and beyond the needs of other large programs such as NSF's Ocean Observatories Initiative or activities falling within the realm of ocean exploration. Approach and Information Needs To evaluate future directions of deep submergence science in the United States, as well as the facility requirements and range of deep sub- mergence technologies needed to conduct this science, a number of issues had to be considered. In an effort to evaluate options, the committee chose to systematically examine the question in terms of scientific need, techni- cal requirements, necessary capabilities, and appropriate capacity. As the capabilities of both HOVs and unoccupied vehicles evolve, the demand for these platforms will also evolve (for example, if the enhancements rec- ommended in Chapter 4 for NDSF's HOV are followed, the user base for that HOV will likely diversify and expand). The committee has declined to be drawn into a rhetorical debate about the proper mix of platforms 10 to 20 years in the future. The DESCEND (Developing Submergence SCiencE for the Next De- cade) report identified a number of laudable scientific goals but did not specify the unique role that deep submergence science would play or spe- cifically what capabilities are needed to support targeted research to achieve these goals (UNOLS, 1999~. There is a general and detailed list of desired capabilities, but these are not mapped to specific research initia- tives. Input from the deep submergence community and a variety of oceanographic disciplines helped determine the science requirements, the geographic locations, depth ranges, and the current and future technolo- gies needed for deep submergence science. Understanding the limitations imposed on research carried out in the
OCR for page 19
INTRODUCTION 19 deep ocean requires knowledge of the mechanisms for awarding research funds and providing access to needed technology (e.g., as currently un- derstood, obtaining funding and obtaining access to equipment involve separate processes). While Alvin and Jason II are currently oversubscribed, suggesting that demand exceeds availability, information on the pattern of use, criteria used to evaluate requests, rate of request denials, and rela- tionship of scheduling access to resources maintained by NDSF was ex- amined. Similarly, information on the funding proposal review processes used by NSF, likely level of funds to support research, and proposal suc- cess rates was also considered. The technical capabilities for conducting deep submergence science have been examined extensively. Documents such as a 2001 article in the Marine Technology Society Journal on the development of undersea tech- nologies (Rona, 2001), the 1999 DESCEND report (UNOLS, 1999), Under- sea Vehicles and National Needs (NRC, 1996), The Global Abyss report (UNOLS, 1994), and Submersible Science Study for the l 990s (UNOLS, 1990) offer insights into the thinking of at least some subset of the user commu- nity. The present study expands on the perceived research needs and ca- pabilities for the future. For example, the role of unique capabilities to enable high-priority science (i.e., how factors like human presence versus extended bottom time or range enable specific research efforts) is dis- cussed and evaluated with respect to determining the depth capabilities and pattern of use for Alvin and other deep submersibles. Threshold depths and their corresponding geologic features (e.g., continental slope, abyssal plain, mid-ocean ridges, and deep trenches) are evaluated as an aid in determining the needs for deep ocean research platforms within the United States. The strengths and limitations of using HOVs, ROVs, and AUVs are discussed in detail to help specify the future needs for deep submergence assets as mapped to specific mission goals. As the only NDSF HOV, Alvin's capabilities, strengths, and limita- tions have been evaluated (e.g., visibility, payload, bottom time, maneu- verability) and recommendations made that consider deep submergence needs weighed against respective costs and benefits. Within the overall context of deep submergence science, use of Alvin is considered only as a component of an entire suite of DSV assets. In consideration of deep sub- mergence needs and Alvin's important role, various options are provided that range from keeping Alvin as is, to improving it, to replacing it with a variety of different configurations. These replacement or modification options offer a range of improvements (e.g., improved bottom time, ma- nipulator dexterity, data transmission, payload, and visibility) at various cost levels. With adequate maintenance, Alvin could operate well into the fore- seeable future. Although near-term replacement of Alvin may not be nec-
OCR for page 20
20 FUTURE NEEDS IN DEEP SUBMERGENCE SCIENCE essary, there is reason to believe that expanded capabilities are needed to support deep ocean research more fully. Potential construction costs for its replacement, as well as alternative designs and subsystem replace- ments for its upgrade, with consideration of annual maintenance and op- erating costs, are presented to inform a decision on whether to maintain, upgrade, or replace the Alvin. Early in the study, the potential role of a full-ocean-depth HOV was raised. During subsequent discussions it was concluded that giving seri- ous consideration to the potential construction and viability of an 11,000- m HOV was beyond the scope of the charge to the committee. The design and construction of such a vessel cannot be completed within the two-to three-year time frame NSF/OCE currently has to fund and initiate the construction of a possible HOV. For example, all of the existing deep- diving HOVs are designed around a sphere. To develop an HOV using proven designs and materials with similar occupant volume, while in- creasing the depth capability from 6,500 to 11,000m, would require dou- bling the weight of the sphere. For the new 6,500-m DSV, the titanium hull weight is approximately 11,000 pounds, or one-third the total HOV weight of 32,000 pounds. Doubling the sphere weight would nearly double the full-ocean-depth HOV weight and would place it well beyond the capacity of the support ship Atlantis. Modifying the Atlantis to handle a vehicle of such weight would place the total cost well beyond the NSF budget. Even if all of the components necessary to build an 11,000m HOV were available off the shelf, there is no certification test facility for such pressures. Given these limitations, it is simply not feasible for NSF to de- sign and build a full-ocean-depth HOV for $25 million in two years. Given the short time available to provide NSF with advice, the committee fo- cused on examining feasible options. Therefore, design approaches and the scientific value of a full-ocean-depth vehicle were not explored. The potential utilization of non-U.S. facilities (e.g., HOVs from the Japanese Marine Science and Technology Center and the French Institute for Exploration of the Sea) was explored, but except for the Russian Mirs, which are available for lease, this option does not appear to be practical. The principal impediment is that the vehicles and their support vessels are typically fully scheduled with the needs of their home countries. ORGANIZATION OF THE REPORT The main focus of this report is to provide the evidence and argu- ments needed, as well as a range of options, to evaluate the greatest deep submergence vehicle capability for a set dollar amount. These issues are discussed at length and provide NSF with a list of possibilities for main- taining and improving NDSF assets.
OCR for page 21
INTRODUCTION 21 Chapter 2 begins by defining deep submergence science. It documents the diverse nature of deep submergence science and describes the types of science conducted in the deep ocean as well as the geographic locations for current and proposed research. The hazards and difficulties of work- ing at depth are outlined and the suite of available deep submergence platforms is introduced. Chapter 3 further documents the strengths and limitations of various platform designs within the current suite of NDSF assets. An analysis of the number, suitability, and distribution of existing deep submergence assets (including non-NDSF vehicles) is made to support calls for expan- sion of available assets by improving current vehicles as well as adding other assets. Chapter 4 explores the options for providing greater capabilities over a broader geographic range and articulates the justification for improving access to, and the utilization of, the nation's deep submergence assets. Additionally, options for upgrading individual components of ROVs and HOVs are presented as they relate to general mission goals. The chapter's focus is on improving the overall capability of the deep submergence fleet, including the standardization of tool sets and interfaces to be used on a broader range of deep-diving vehicles, HOVs and ROVs combined. Chapter 5 brings together the individual findings to provide a coher- ent vision of how the agencies should support deep submergence science in the next 10-20 years. Appendix A contains biographical sketches of members of the Com- mittee on Future Needs in Deep Submergence Science. Although acro- nyms used in this report are redefined in each chapter, a complete list is provided in Appendix B. Appendix C contains a list of AUVs and their home institutions. Appendix D is a table of Jason II and the proposed HOV estimated subsystem weights and costs.
OCR for page 22
Representative terms from entire chapter: