Andrew D. Bowen

Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise

Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global mid-ocean ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultraslow spreading ridges that were the last to be demonstrated to host high-temperature venting but may host systems particularly relevant to prebiotic chemistry and the origins of life. Here we report evidence for previously unknown, diverse, and very deep hydrothermal vents along the ∼110 km long, ultraslow spreading Mid-Cayman Rise (MCR). Our data indicate that the MCR hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultramafic systems and, at ∼5,000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent types identified here and their relative geographic isolation make the MCR unique in the oceans. These new sites offer prospects for an expanded range of vent-fluid compositions, varieties of abiotic organic chemical synthesis and extremophile microorganisms, and unparalleled faunal biodiversity—all in close proximity.

Acoustic measurement of the Deepwater Horizon Macondo well flow rate

On May 31, 2010, a direct acoustic measurement method was used to quantify fluid leakage rate from the Deepwater Horizon Macondo well prior to removal of its broken riser. This method utilized an acoustic imaging sonar and acoustic Doppler sonar operating onboard a remotely operated vehicle for noncontact measurement of flow cross-section and velocity from the well’s two leak sites. Over 2,500 sonar cross-sections and over 85,000 Doppler velocity measurements were recorded during the acquisition process. These data were then applied to turbulent jet and plume flow models to account for entrained water and calculate a combined hydrocarbon flow rate from the two leak sites at seafloor conditions. Based on the chemical composition of end-member samples collected from within the well, this bulk volumetric rate was then normalized to account for contributions from gases and condensates at initial leak source conditions. Results from this investigation indicate that on May 31, 2010, the well’s oil flow rate was approximately 0.10 ± 0.017 m3 s-1 at seafloor conditions, or approximately 85 ± 15 kg s-1 (7.4 ± 1.3 Gg d-1), equivalent to approximately 57,000 ± 9,800 barrels of oil per day at surface conditions. End-member chemical composition indicates that this oil release rate was accompanied by approximately an additional 24 ± 4.2 kg s-1 (2.1 ± 0.37 Gg d-1) of natural gas (methane through pentanes), yielding a total hydrocarbon release rate of 110 ± 19 kg s-1 (9.5 ± 1.6 Gg d-1).

Hawaii‐2 observatory pioneers opportunities for remote instrumentation in ocean studies

Beneath 5000 m of water midway between Hawaii and California, the Hawaii-2 Observatory (H20) rests on the seafloor (Figure 1). Telemetry and power come to this pioneer, deep-ocean scientific observatory via a retired telephone cable, Hawaii-2, donated by AT&T to the Incorporated Research Institutions for Seismology (IRIS) Consortium for the benefit of the scientific community. H20 is the first Global Seismographic Network (GSN) station on the seafloor.With a suite of wet-mateable connectors on a junction box (j-box), H20 offers marine scientists a new opportunity to deploy and operate remote instrumentation in the middle of the ocean.

The Nereus hybrid underwater robotic vehicle for global ocean science operations to 11,000m depth

This paper reports an overview of the new Nereus hybrid underwater vehicle and summarizes the vehicles performance during its first sea trials in November 2007. Nereus is a novel operational underwater vehicle designed to perform scientific survey and sampling to the full depth of the ocean of 11,000 meters - almost twice the depth of any present-day operational vehicle. Nereus operates in two different modes. For broad area survey, the vehicle can operate untethered as an autonomous underwater vehicle (AUV) capable of exploring and mapping the sea floor with sonars and cameras. For close up imaging and sampling, Nereus can be converted at sea to operate as a tethered remotely operated vehicle (ROV). This paper reports the overall vehicle design and design elements including ceramic pressure housings and flotation spheres; manipulator and sampling system; light fiber optic tether; lighting and imaging; power and propulsion; navigation; vehicle dynamics and control; and acoustic communications.

Integrating Precision Relative Positioning into JASON/MEDEA ROV Operations

Advances in navigation continue to add precision and robustness to undersea operations. Two challenges limit navigation of the JASON/MEDEA two-vehicle ROV system: acoustic noise from JASON’s hydraulic systems and lack of a direct relative position measurement between the two vehicles. This paper describes successful integration of the SHARPS ranging system—enabling precise relative positioning that is robust with respect to acoustic noise. We discuss four aspects of the installation: the capabilities of SHARPS as installed on the ROVs, the estimation theory predicted performance of the system design, the proof-of-concept navigation results from field deployments, and the operational utility of the SHARPS capability. The SHARPS installation integrates an important capability into the ROV system, enhancing the data product for science while adding safety and flexibility to the at-sea operations. hangs below the dynamically positioned (DP) surface ship via an armored cable carrying fiber-optic communications and electric power. The vehicle’s large, concentrated mass decouples the ROV, JASON, from the surface ship’s motion, keeping the armored cable vertical and reducing the chance of snap-loading from surface heave. A 35 m neutrally buoyant tether connects the two vehicles, extending the communication and electric power to JASON. Operators move the ship to position MEDEA vertically over-top of JASON, maintaining visual contact using a down-looking low-light camera on MEDEA and adjusting the vertical separation between the two vehicles. During lowerings lasting as long as 72 hours, JASON samples and surveys the seafloor at depths of up to 6,500 m. One of the most important data products of this work is the record of navigation estimates. These records allow scientists to systematically and quantitatively explore the seafloor. Because of the JASON/MEDEA two-body configuration, short baseline (SBL) relative positioning improves the navigation solution, allowing safer, more flexible operation. Operators navigate the JASON/MEDEA ROV system using a combination of long baseline (LBL) positioning and Doppler velocity log (DVL) dead-reckoning. Both JASON and MEDEA have LBL receivers, but only JASON has a DVL to measure velocity relative to the seafloor. There are two challenges with the current navigation solution. First, LBL reception at JASON’s receiver is inconsistent or non-existent due to acoustic noise and limited line-of-sight. JASON’s hydraulic motors power much of the on-board utilities: the two manipulators, tool basket, suction pumps, etc. The associated acoustic

Argo/Jason A Remotely Operated Survey And Sampling System For Full-ocean Depth

Abstract : The ARGO/JASON system is an integrated system that performs survey and sampling to depths of 6000 meters. This paper summarizes the capabilities of the system and includes descriptions of three vehicles: the deep-towed imaging sled ARGO, the ROV JASON, and the sidescan sonar DSL-120.

EXPLORING THE DEEPEST DEPTHS: PRELIMINARY DESIGN OF A NOVEL LIGHT-TETHERED HYBRID ROV FOR GLOBAL SCIENCE IN EXTREME ENVIRONMENTS

This work details a new effort to build an operational underwater vehicle that can perform scientific survey and sampling to the full depth of the ocean (11,000 m). The vehicle, called a hybrid remotely operated vehicle (HROV), will operate in 2 different modes. For broad area survey, the vehicle will operate untethered as a autonomous underwater vehicle (AUV) capable of exploring and mapping the seafloor with sonars and cameras. After targets of interest have been found, the vehicle will be converted at-sea to become a remotely operated vehicle (ROV) that will enable close up imaging and sampling. The ROV configuration will incorporate a lightweight fiber-optic tether to the surface for high bandwidth real-time video and data telemetry to the surface to enable highquality teleoperation, additional cameras and lights, a manipulator arm, and sampling gear. The paper outlines the scientific motivation for the project as well as feasibility of the design concept. Analysis of the fiber-optic cable shows the approach taken to be practical even with fairly extreme current profiles. An overall approach to the vehicle design is given, including options for pressure housings and buoyancy materials.

Proof of concept demonstration of the Hybrid Remotely Operated Vehicle (HROV) light fiber tether system

The Hybrid Remotely Operated Vehicle (HROV) Nereus, developed by the Woods Hole Oceanographic Institution (WHOI) with the support of the Space and Naval Warfare Systems Center San Diego (SSC San Diego) and the Johns Hopkins University, is intended to provide a new level of access for deep oceanographic research to a maximum depth of 11,000 meters. Nereus operates in two different modes. The vehicle can operate untethered as an autonomous underwater vehicle (AUV) for broad area survey, capable of exploring and mapping the seafloor with sonars, cameras, and other on-board sensors. Nereus can be converted at sea to become a remotely operated vehicle (ROV) to enable close up imaging and sampling. The ROV configuration incorporates a lightweight fiber optic tether to the surface for high bandwidth real-time video and data telemetry to the surface to enable high-quality teleoperation, additional cameras and lights, a manipulator arm, and sampling gear. Development of the fiber tether system was supported by both simulation and extensive field testing over a three year period. These tests demonstrated that an unprotected optical fiber could survive in the water column for greater than 24 hours and be effectively used as a high bandwidth data link by a remotely-operated, self-powered vehicle. Based on the data from the fiber trials, a robust tether deployment system was designed. The tether deployment system was integrated with the vehicle and demonstrated during field trials in November 2007.

Field Tests of the Hybrid Remotely Operated Vehicle (HROV) Light Fiber Optic Tether

The Hybrid Remotely Operated Vehicle (HROV), being designed and built by Woods Hole Oceanographic Institution (WHOI) with the support of the Space and Naval Warfare Systems Center San Diego (SSC San Diego), will provide a new level of accessibility for deep ocean research. HROV will be primarily an autonomous vehicle but will be reconfigurable to a teleoperated system by the installation of a fiber optic data link and a manipulator based work system. Development of the fiber optic link has been supported by both simulation and a series of field tests over the past 3 years. The November 2004 tests consisted of deploying two different types of fiber optic cable from an Oceanographic elevator deployed from a ship to 2000 m depth. Data collected from this test demonstrated the feasibility of using both the Fiber Optic Microcable (FOMC) and plain buffered optical fiber as a tether for the HROV. The December 2005 tests demonstrated the utility of the buffered optical fiber operating on an underwater vehicle using the WHOI ABE vehicle as a substitute for the future HROV. Five dives were made to 2000 m with real-time communication from the vehicle to the surface via the fiber. The May 2006 tests focused on the employment of a cable depressor and deployment system. Using a deep elevator as a substitute for HROV, the fiber was deployed from both the depressor and the elevator to a depth of 4200 m. Over the course of 4 deployments, over 16 km of fiber was deployed, operating for a total of 33 hours, demonstrating the feasibility of the planned approach

Design of Nereid-UI: A remotely operated underwater vehicle for oceanographic access under ice

This paper reports the development of a new underwater robotic vehicle, Nereid-UI, with the goal of being capable of deployments in polar ocean regions traditionally considered difficult or impossible to access such the ice-ocean interface in marginal ice zones, in the water column of ice-covered seas, and the seas underlying ice shelves. The vehicle employs a novel lightweight fiber-optic tether that will enable it to be deployed from a ship to attain standoff distances of up to 20 km from an ice-edge boundary under the real-time remote-control of its human operators, providing real-time high-resolution optical and acoustic imaging, environmental sensing and sampling, and, in the future, robotic intervention.