This is a collaborative proposal from Principal Investigators from Woods Hole Oceanographic Institution (WHOI) and the University of Texas-Austin. They will study hydrothermal processes on the Gakkel Ridge in the Eastern Arctic Basin. The Gakkel Ridge is a key target for hydrothermal studies because it has distinctive geological characteristics as a result of ultra-slow spreading and it is hydrographically isolated from the world's ocean basins, which have important implications for vent field biological communities. Although thermal and particulate signatures indicative of hydrothermal fluids were found in nearly 80% of the CTD casts from the recent U.S./German Arctic Mid-Ocean Ridge Expedition (AMORE) in 2001, no vent fields have been sampled because the ice cover precludes the use of ROVs and submersibles. The Principal Investigators will solve the technical challenges imposed by the ice pack by utilizing nested surveys with autonomous underwater vehicles (AUVs) to map water column plumes, locate buoyant plume stems, conduct fine-scale micro-bathymetric surveys, and to generate photomosaics of the biological communities. They will use the AUV survey data to identify geological and biological sampling targets, and then use a combination of wireline and semi-autonomous methods to obtain the samples. They will complement and guide the AUV and sampling efforts with a more traditional, comprehensive CTD/hydrocast program to measure key parameters such as methane, hydrogen, and manganese in the overlying hydrothermal plumes. These chemical measurements will provide a first indication of important vent fluid characteristics such as the redox environment and the involvement of ultramafic rocks. Based on the CTD, dredging, and mapping results from the AMORE expedition, the Principal Investigators identified two target areas with contrasting geological characteristics. They have leveraged the funds requested from NSF with a NASA Astrobiology grant recently awarded to WHOI and the University of Maryland's Space Systems Laboratory. NASA's interests lie in technology development for autonomous extra-terrestrial sample return, and the grant provides more than $3M to support the AUV component for the field program as an analogue for future missions to Europa. In this current project, they request funds solely for water column CTD work, wireline sampler development, and sample analyses.
Broader Impacts: Hydrothermal circulation is a fundamental physical process within the Earth that gives rise to spectacular deep-sea vent fields hosting exotic, chemosynthetic biological communities. Deep-sea vent fields have provided an exciting, multi-disciplinary field of research since their initial discovery in 1977, and the potential for organic compounds to be abiotically synthesized in deep-sea hydrothermal systems may prove to have profound implications for the origin of life on our planet. This research will extend our knowledge of these systems by characterizing hydrothermal processes on a geologically and hydrographically unique mid-ocean ridge. These topics have broad societal interest, and will bring appropriately packaged aspects of the research to the public through a formal education and outreach component already funded in the NASA Astrobiology grant. These activities will include the development of educational modules by a teacher for the highly acclaimed Dive and Discover website (www.divediscover.whoi.edu), followed by their participation in the Gakkel expedition and will bring the cruise activities to middle and high school classrooms and to the general public in near real-time.
WHOI and the University of Maryland's Space Systems Lab have obtained a grant from NASA's Astrobiology Science and Technology Experiment +Program (ASTEP) that has provided more than $3M to merge robotics technologies with AUVs to enable autonomous sample collection for future missions to Europa, and to demonstrate the system by performing remote sampling of hydrothermal vents in the Arctic Ocean. The NASA grant will support the AUV component of Arctic Ocean field program.
One of the proposed options in the ANS proposal for sample recovery is to use a simple, towed system with real-time data return and shipboard control for triggered sampling. This sampling platform has no thrusters, so it cannot be maneuvered except by moving the ship, but it can operate independently and provides a relatively inexpensive system for high quality imaging and sampling at Arctic deepsea vent fields. The Drop Camera System (DCS) consists of a metal frame that includes a digital camera, lights, a depth sensor, a CTD, and a mechanical sampling device capable of multiple samples. The conceptual idea is to use a combination of a claw-style dredge and a slurp gun that can be lowered for sampling with a set of rotating sampling containers. The entire frame would be connected to the icebreaker using standard 0.68" EMO cable. The DCS will be navigated using a relay transponder near the end of the wire and a long-baseline transponder network that will be deployed on the seafloor at each target site (these transponders will also be used to help navigate the AUV surveys). The software interface will be derived from software that runs the National Deep Submergence Facility towed vehicle Argo and associated platforms. All data is converted to ethernet via ethernet-to-RS232 interface converters and analog controlled circuitry. The camera imagery is available in digital format and will be packeted for telemetry. The ethernet data will be piped up the fiber to the surface via a ethernet fibre converter, where it will be logged, displayed in real-time, and also used to allow for individual sensor parameter control. A similar software and control system has already been developed at WHOI and deployed on the shallow water "Habcam" towed system for biological habitat characterization. After seafloor vent field targets have been identified through a combination of CTD and AUV surveys, the Principal Investigators will use the icebreaker to clear a lead for the DCS deployment. They will plan the deployment so that the icebreaker will drift with the ice pack over the target area. In a typical deployment scenario, the DCS will be towed 5-10 meters above the seabed at slow speeds. High dynamic range imagery will be telemetered in real-time to the icebreaker allowing them to make linear photomosaics of the seafloor, and will have command-control capability to deploy the sampler based on the real time digital imagery.
