NEPTUNE

Real-Time, Long-Term Ocean and Earth Studiesat the Scale of a Tectonic Plate

John Delaney1, Alan Chave2, G. Ross Heath1, Bruce Howe3, Patricia Beauchamp4

1School of Oceanography, University of Washington, Seattle, WA 2Woods Hole Oceanographic Institution, Woods Hole, MA

3Applied Physics Laboratory, University of Washington, Seattle, WA4Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA

ABSTRACT

The NEPTUNE project will establish a linkedarray of undersea observatories on the Juan de Fucatectonic plate. The NEPTUNE infrastructure,consisting of fiber-optic/power cable and junctionboxes, will provide significant amounts of powerand an Internet communications link to sensors andsensor networks on, above, and below the seafloor.This observatory will provide a new kind ofresearch platform for real-time, long-term, plate-scale studies in the ocean and earth sciences.

INTRODUCTIONThe NEPTUNE project is developing a fiber-

optic/power network of distributed sensors on,above, and below the Juan de Fuca tectonic plate inthe northeast Pacific Ocean (Figure 1a,b).Scheduled to be operational by 2006, theNEPTUNE observatory will provide a new kind ofresearch platform for real-time, long-term, plate-scale studies in the ocean and earth sciences.

The planned 30 experimental nodes for theNEPTUNE system could be distributed over avolume extending from the air–sea interface to thebottom of the oceanic crust and will cover an areathat includes the entire Juan de Fuca Plate, itsmargins, and beyond. These in situ n o d a lobservatories will be spaced approximately 100 kmapart on the network. Each will have a significantfootprint of instruments bounding a volume ofocean space. These arrays will permit remoteinteraction with physical, chemical, and biologicalphenomena operating across multiple scales ofspace and time. Observatories in key areas ofinterest will be spatially extensive, covering areasup to 50 km in diameter. It will be possible to

extend NEPTUNE’s cable-defined footprintthrough the use of moored and relocatable buoys.

The electro-optical cable will providesignificant power and high-bandwidthtelecommunication capabilities to this array ofinstruments and sensors, permitting real-time datatransmission and remote two-way command-control of instruments and robotic underseavehicles. Data will flow in real time fromNEPTUNE’s in situ facility to land-based scientists,educators, decision makers, and learners of all ages(Figure 2).

NEPTUNE offers a new means of observingand understanding our planet. It will foster a moreintegrated era of research and education in theocean and earth sciences and may also serve as aunique testbed for sensor and robotic systemsdesigned to explore other oceans in the solarsystem.

PARADIGM SHIFT IN THE OCEAN SCIENCESTraditional expeditionary science has

characterized some portion of an ocean or planetwithin the constraints of data collection from a shipor spacecraft. Such time-limited visits areinadequate to fully evaluate the suite of models andtestable hypotheses that have grown out of thisexploratory work.

Ocean scientists now stand on the threshold of ascientific revolution, a paradigm shift madepossible by advances in computationalsophistication, communication and powertechnologies, robotic systems, and sensor design.The ability to enter, sense, and interact with thetotal ocean environment is within our grasp. It istime to expand beyond short-term expeditions usingresearch vessels; it is time to move toward a

Figure 1 (a) NEPTUNE cable system map. NEPTUNE will provide power and communications bandwidthvia fiber-optic/power cable to junction boxes (nodes) on the Juan de Fuca Plate and surrounding areas. Byconnecting sensor networks to the nodes, with extensions onshore and offshore into the interior, scientistswill for the first time have the capability to study a host of interrelated processes with high spatial andtemporal resolution over long periods of time. (b) A generic NEPTUNE observatory network, draped overAxial Volcano and based on the NOAA/PMEL New Millenium Observatory.

Figure 2. Land-based scientists and the public are linked in real time and interactively with sensors, sensornetworks, and various mobile sensor platforms in, on, and above the seafloor. NEPTUNE’s fiber-optic/power cable and associated technology provide the enabling network infrastructure.

long-term presence on, above, and below a sectionof seafloor as large as a tectonic plate.

NEPTUNE’s plate-scale observatory concept isbased on the following premises:

• Many globally significant planetaryphenomena, involving both oceanographic andsolid earth processes, operate at or below the scaleof a tectonic plate.

• Thorough four-dimensional examinationof at least one plate/mesoscale system will generatemajor new insights into all such systems.

• Understanding the interactions among themyriad processes operative at such scales willrequire decadal commitment to the studies.

A recent U.S. National Research Council report(NRC, 2000) concluded that “Seafloorobservatories present a promising, and in somecases essential, new approach for advancing basicresearch in the oceans.” Based on this report’srecommendations, the National Science Foundationhas proceeded with a new program to support long-term research observations and interactiveexperiments from the sea surface to the seafloorand beneath. NEPTUNE anticipates participating as

the regional, tectonic-plate-scale component of thisOcean Observatories Initiative.

Observatories such as NEPTUNE will createopportunities to address such compellingintellectual and societal themes as the search for lifewithin and beyond earth, anticipation of cripplingnatural hazards, improved management of marineresources, anthropogenic influences on ocean andclimate systems, and a deeper understanding ofhabitat complexity.

INNER SPACE/OUTER SPACEThe spectrum of scientific studies currently

envisioned for the NEPTUNE facility covers abroad range. One major opportunity arises fromrecent evidence that submarine volcanoes support asubstantial, unexplored high-temperature microbialbiosphere sustained by volatile fluxes from theearth’s interior. This insight implies that seafloorhydrothermal vent fields may be the “tips oficebergs” in total biomass supported by activesubmarine hydrothermal systems. A significantmicrobial biosphere apparently thrives within thebrittle outer shell of the volcanically activesubmarine portions of earth.

Similar submarine volcanic systems may existon other solar bodies, such as Europa, the secondmoon of Jupiter. The new field of microbialvolcanic ecology is, therefore, doubly powerful. Bydesigning innovative strategies to explore therelationships between volcanoes and the life theysupport here on earth, we gain not only essentialknowledge about newly discovered processes andlife forms on our own planet, but also critical newinsights into how we might explore for signs of lifeon other solar bodies. NEPTUNE will allowintimate real-time access to the vigorousgeophysical and geochemical processes that sustainthis sub-seafloor volcanic biosphere.

NEPTUNE may also serve as a unique testbedfor sensor and robotic systems designed to exploreother oceans in the solar system. Indeed, we canregard NEPTUNE as an inward-looking Hubbletelescope, vastly enhancing the potential fordiscovery by allowing unprecedented four-dimensional imagery of planetary processes notentirely restricted to earth: by looking inward,focusing on integrated, scientific experimentationin remote or hostile environments on our ownplanet, we will also be looking outward.

THE NEPTUNE STUDY AREATo attract the broadest possible user base to this

full-service oceanographic research platform and tominimize cost, we sought a study area that had asmall footprint but encompassed myriad importantearth and ocean processes. The Juan de Fuca platewas chosen for its representative spectrum ofglobally occurring earth-ocean processes andbecause it is in an ideal location close to majorports in British Columbia, Washington, andOregon. The Plate is small and entirely submarine,and we propose treating the entire system as anocean-earth laboratory (Delaney et al., 2000).

THE FEASIBILITY STUDYOne of NEPTUNE’s important early efforts was

completion of a feasibility study in June 2000(NEPTUNE Phase 1 Partners, 2000). The study wasfunded by the National Oceanographic PartnershipProgram and by the four NEPTUNE Phase 1partners (University of Washington, Woods HoleOceanographic Institution, the California Instituteof Technology’s Jet Propulsion Laboratory, andNOAA’s Pacific Marine EnvironmentalL a b o r a t o r y ). Many other institutions andindividuals contributed generous time and effort tothe feasibility study. Since completion of the study,two more partners have joined the project:Canada’s Institute for Pacific Ocean Science and

Technology (IPOST) and the Monterey BayAquarium Research Institute (MBARI).

The feasibility study, which is posted on theN EP TU NE web s ite (www.n ep tun e.was hing ton .ed u) ,concluded that 1) there are strong intellectual andsocietal drivers for implementing NEPTUNE,2) NEPTUNE is feasible from a technological pointof view, and 3) within the context of whatNEPTUNE brings to the earth, ocean, and planetarysciences, the system cost is reasonable.

SCIENTIFIC OPPORTUNITIES/SOCIETAL BENEFITS

We will be able to address a host of scientificopportunities and societal challenges with thecapabilities envisioned for NEPTUNE. Indeed, theultimate measure of success of any scientificfacility is the innovative character and quality ofthe scientific research and public education that areenabled.

The ad hoc science working groups listed belowwere convened to hold brainstorming sessions toidentify research opportunities that NEPTUNEcould enable and to develop preliminary examplesof science experiments.

• Cross-margin particulate fluxes• Seismology and geodynamics• Seafloor hydrogeology and

biogeochemistry• Ridge-crest processes, subduction zone

processes (fluid venting and gas hydrates),• Deep-sea ecology• Water-column processes, and• Fisheries and marine mammals.

The working groups addressed the scientificviability of large, long-term group or communitystudies and of shorter-term individual investigatorexperiments and observations. The white papersproduced by these working groups are posted onthe NEPTUNE web site. Listed below are some ofthe scientific opportunities and societal benefits thatwill be engendered by NEPTUNE.

For the first time, using NEPTUNE,earthquake and deformation patterns associatedwith the creation, aging, and destruction of oceanicplates can be examined in a continuous, integratedfashion for decades. The NEPTUNE study areaincludes all major types of oceanic plateboundaries, including the Cascadia subduction zone(Fluck et al., 1997; Wang et al., 1997). A seafloorseismic network will capture the earliest signalsfrom great subduction zone earthquakes and cancontribute critical information to tsunami andground-shaking warning systems. NEPTUNE is

very complementary to U.S. and Canadianinitiatives to enhance land-based observations.

• Ridge-crest volcanism is intimately related tothe formation of metal deposits, modulation ofseawater compositions, local heating of theoverlying ocean, and support of a microbialbiosphere. NEPTUNE’s capabilities will helpestablish the specific nature of links and variationsbetween geological, physical, chemical, andbiological processes at active mid-ocean ridges(Delaney et al., 1998). A crucial use of NEPTUNEwill be rapid response to eruptions of submarinevolcanoes to sample the exotic microbiologicalmaterials released there. Enzymes extracted fromdiverse microbial communities supported byextreme conditions within the ocean and underlyingcrust are and will be sources of bioactive materialsfor powerful industrial applications. The ability totrack and sample otherwise undetected eruptiveevents will give us new access to such compounds.

• Despite the vigor of ridge-crest activity, itconstitutes less than 10% of the total global flux ofheat and chemicals from the earth’s interior. Ridgeflanks and mid-plate portions of our planetrepresent the zones of major heat and chemicalt r a n s f e r from the earth’s interior to thehydrosphere and biosphere. Instrumented boreholeswithin the oceanic crust can serve as laboratoriesfor studying the interdependence of tectonics, fluidand thermal flows, and biological activity (Davis etal., 1995). Early evidence indicates that theserelationships are at least partially forced by tides,but the ramifications are not clear. Intriguing newdata suggest that plate activities may be moreinterconnected than previously suspected.

• Studies of the volatile fluxes expelled along asubduction zone will allow cross-correlation withmajor and minor earthquake activity, thus givingcrucial information about potentially major, non-steady-state carbon movements. The role ofsubduction gases and methane hydrates in thedynamics of the continental slope is virtuallyunknown. The classic study site for fluid ventingand gas-hydrate formation and breakdown islocated within the NEPTUNE study area (Suess etal., 1999). Global interest in hydrates reflects theirrole as a vast potential energy resource and asignificant source of greenhouse gases.Documentation of the formation and accumulationrates of gas hydrates, as well as metal deposits, willprovide new insights into the search for scarceresources.

• Migration of fish stocks and marinemammals along and across the continental shelfcan be quantitatively tracked using innovativeacoustic techniques (McDonald and Fox, 1999).

Tying this to small- and large-scale oceanographyand the regional carbon budget will be a worthychallenge.

• A fully instrumented suite of water-columnmoorings will allow continuous four-dimensionalreal-time assessment of the physical, chemical, andbiological interactions in a zone of divergence andin nearshore upwelling processes. Collectingmodel-guided, continuous, long-term data serieswill improve current models of the oceanicprocesses that occur in the NEPTUNE study areaand could fundamentally re-orient biologicalapproaches to ocean science (e.g., Haidvogel et al.,2000 and Glenn et al., 2000). NEPTUNE will alsoprovide the capability to conduct uniquequantitative assessments of certain portions of thecarbon cycle.

• Sediment transport along and across thecontinental shelf and into the deep ocean can bequantified as a function of the processes that drivesuch systems. Large fluxes of sediment laden withcarbon and anthropogenic chemicals cross thenortheast Pacific continental shelf to the adjacentdeep-sea floor in a highly episodic fashion duringmajor storms (Nittrouer and Wright, 1994). Themechanisms, however, are largely unknown.NEPTUNE’s capabilities will permit measuring,sampling, and experimentation during theseepisodic events. A more complete understanding ofwater-column physics, chemistry, and biology willpermit addressing the links between primaryproductivity, fisheries, marine mammal migration,and deep-sea ecology.

• The deep sea represents two-thirds of ourplanet yet is virtually unexplored in terms ofbiocomplexity. The NEPTUNE network willprovide the capability to develop a functionalunderstanding of the ecology of deep-sea biota,only a small percentage of which have beensampled or identified (Smith et al., 1997).

ENG IN EER IN G O VERV IEW A ND I NFRA STR UC TU R E

Moo red Buo ys vs . Ca b le. There ar e tw o d is tin ctapp ro ach es to p ro vid in g p ow er an d communicationsto a distributed set of seafloor science nodes: 1) adistributed set of buoys, each linked to a seafloorscience node, and 2) a seafloor fiber-optictelecommunications cable connecting a distributedset of science nodes to one or more shore stations.In the first case, the moored surface buoys supplypower to the seafloor instruments and provide asatellite data link to land. In the second case, theseafloor fiber-optic telecommunications cable linksthe science nodes to one or more shore stations.Selecting the most appropriate approach depends

on the amount of power needed for seafloor nodesand science instruments, on the maximumanticipated data rate over the lifetime ofNEPTUNE, and on cost.

Power and data-rate issues argue stronglyagainst the use of buoy technology for the coreportions of the NEPTUNE array. The use of buoyswould place significant limitations on NEPTUNEexperiments because the power requirement forNEPTUNE exceeds the several hundred watts thatcould be provided by buoys. Similarly, the requireddata rate capacity for a NEPTUNE science nodeexceeds that which a satellite link can service byseveral orders of magnitude. In addition, therequired technological developments andcommercial uncertainty surrounding availablesatellite systems further weakens the case for theiruse.

Underwater fiber-optic telecommunicationscable technology, however, is highly advanced andcommercially available. It is capable of handlingthe higher data rates needed for NEPTUNE andproviding the needed levels of power to theseafloor. Using a non-standard approach for powerdelivery, it is feasible to send many tens ofkilowatts to the seafloor. For these reasons, wehave selected the cable approach for NEPTUNE.

Observatory requirements. NEPTUNE’s infra-structure must meet the following requirements ofthe scientific program:

• Bandwidth capable of supporting HDTVand acoustic tomographic studies at manynodes

• Power to operate autonomous underwatervehicles (AUVs) and bottom rovers

• Very accurate timing signals to supportdense seismometer arrays

• Real-time information on the status ofinstruments

• Real-time ability to change measurementparameters and download data

• Reliable time series measurements, and• User-friendly information management

system.To meet these requirements, NEPTUNE is

planning at least two shore stations: one inVictoria, Canada, which will include a majorvisitors’ center, and one in the U.S., most likely inNedonna Beach, Oregon. Shore stations willprovide power and communications to the cable, aswell as controlling and managing the overallsystem. The main cable, which will be standard,commercial-off-the-shelf cable from the submarinetelecommunications industry, will be buried out toa water depth of about 2000m to protect it from

fishing trawls and will carry power andcommunications to the seafloor nodes, to whichinstruments will be interfaced.

We have selected a mesh network topology forthe power and communications systems to meetcapacity requirements and to maximize reliabilityand flexibility (Chave et al., 2001). The basictrade-offs in the power system design can be madeeasily and mean using a DC "parallel" approachwith self-regulating power supplies, which is unlikeconventional submarine telecommunicationssystems. Our power system designs indicate thatmuch as 100 kW overall can be delivered for theentire 30-node scenario. The basic power needs canbe met with 2 – 10 kW per node. Major powerconsumers include instruments that require motion(AUVs, pumps), heat transfer (freezers to preservespecimens, heaters for polymerase chain reactionsused in DNA work, heaters for clathrate studies),light (video), and “hotel” electronics. The majorconsumers of communications bandwidth are videoand high-frequency acoustics; significant fractionsof a gigabit per second are required at a node, withorder 10 Gb/s required overall.

Gigabit Ethernet, the high-speed version of awidely used data networking technology, has beenselected as the backbone c o m m u n i c a t i o n stechnology that will meet NEPTUNE’srequirements. This dependable and affordablesystem is based on data networking technologywidely used to connect the Internet to laboratories,classrooms, and homes around the world. Theprimary development effort will be in theengineering integration of available, commercial-off-the-shelf components. Innovations will optimizenonstandard approaches to power andcommunications to meet NEPTUNE’s specialneeds.

The Canadian National Research Council’sHerzberg Institute of Astrophysics is leading theNEPTUNE data management and archivingeffort. This Institute, located in Victoria, BritishColumbia, is responsible for the Hubble SpaceTelescope archive in Canada and is one of the keyinstitutions in the Gemini project. The NEPTUNEdata management and archive facility will bedesigned to allow users efficient and seamlessaccess to NEPTUNE data. The approach is basedon distributed archiving of selected data combinedwith robust and reliable data access and miningtools. The facility will provide the scientificcommunity, educators, and the general public withon-line access to all NEPTUNE scientific data toensure maximum use of those data and to guaranteethat data sets are preserved for use by futuregenerations.

Although significant research and developmentare required in the realm of robust, versatilechemical and biological sensors, a suite of existingoceanographic and geophysical instruments isavailable today for straightforward adaptation to theNEPTUNE infrastructure. For these reasons,excellent scientific opportunities and outreachcapabilities can be realized as soon as the system isin place. With time, growing sophistication of newsensors and evolving experimental strategies willstrengthen NEPTUNE’s contributions tooceanography.

EDUCATION AND OUTEACHNEPTUNE’s Internet technology offers great

educational potential. It can provide a wide range ofnew opportunities to explore and investigate thedynamics of the marine world using real-time dataflow to classrooms and living rooms coupled withcutting-edge visualization techniques.

The first workshop on NEPTUNE’s educationand outreach effort was held in November 2000.Sixty-five participants, including science teachers,curricula developers, educators at science centersand aquariums, and scientists, spent two daystogether brainstorming ideas on the best use ofNEPTUNE’s real-time data capabilities in formaland informal science education. A report from thismeeting is posted at www.neptune.washington.edu.

INTERNATIONAL PARTICIPATIONNEPTUNE is an international program. The

study area spans the territory and exclusiveeconomic zones of the U.S. and Canada.Approximately one-third of the Juan de Fuca Platelies within Canadian waters and two-thirds withinU.S. or international waters. In addition to ourNEPTUNE Canada partner, scientists at GEOMARResearch Center for Marine Geosciences in Kiel,Germany are undertaking a long-term, extensivestudy of the gas hydrates found in the HydrateRidge area off the coast of Oregon and will beactive participants in the NEPTUNE scientificprogram. We are also in the process of defining thelevel of participation of a consortium of Japaneseinstitutions.

IMPLEMENTATIONPhase 2, Development, was formally launched

in September 2000 and is loosely defined as allactivities between completion of the FeasibilityStudy and the initiation of activities for Phase 3,Installation. A major Phase 2 effort is theestablishment of science working groups. Their task

will be to conceptualize the design and develop theprototypes of the community experiments.

Activities during Phase 3, Installation, areprocurement and deployment of the NEPTUNEbackbone infrastructure with the initial suites ofsensors for community experiments. Phase 4,Operations, will revolve around four functions:network operations, data management, sensornetwork maintenance, and node and cablemaintenance.

COST ESTIMATESThe estimated cost for the NEPTUNE plate-

scale infrastructure is $100M. A rough estimate forthe cost of a suite of community experiments is$100M, of which $15M is for development.Operating costs are expected to be about$10M/year. (All costs are in year-2000 U.S.dollars.)

SUMMARYThe history of science shows that new

technologies such as telescopes and microscopescommonly result in discoveries that are difficult topredict. By providing continuous access to the timedomain in a well-defined spatial context,NEPTUNE will enable quantum leaps in ourunderstanding of processes in the ocean andunderlying lithosphere. These leaps in turn willtranslate into a greatly improved ability to modeland predict the behaviors of these dynamic parts ofour environment and their impact on our social andeconomic well being. For the first time, the supplyof substantial amounts of continuous power andtwo-way communications to a diverse set of sensorsand interactive experiments will allow science atsea to become as rich and unfettered as science onland.

NEPTUNE will drive improvements in deep-submergence technology and could provideunparalleled test beds for robotic exploration ofextreme habitats, dynamic earth systems, andcomplex oceanographic processes. Internet accessto instrument arrays and robotic systems will allownovel types of involvement by scientists, learners ofall ages, and the general public.

The level of excitement that NEPTUNE and itscapabilities has engendered among members of thebroad marine science community leaves no doubtthat the time to move ahead is now. NEPTUNE’sseries of cabled seafloor instrument sites willprovide a national and international focus forinnovative earth, ocean, and planetary scienceinvestigations, engaging the imaginations ofresearchers and public alike.

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