Collaborative Research: RAPID: Testing High Temperature Subseafloor Tracers and Optical Communication Networks at Axial Seamount Using Available DSV Alvin Bottom Time

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This RAPID project involves two different components. The first component relates to a novel, high-temperature glass material which is being developed for future use as a subsurface fluid flow tracer. The second component further develops a new approach to high-speed underwater sensing and wireless communications networks. Both project components are ambitious experiments that progress the NSF mission by providing foundational engineering research with the long-term potential to transform our approach to ocean science, education and policy.The goal of the first component is to test the stability of a new type of non-toxic, chemically-inert fluorescent glass in hydrothermal vent fluid. If the material can withstand the complex chemical environment of high-temperature vent fluid for an extended duration, it could potentially be used as a tracer for mapping subsurface fluid flow in the future. Such tracer studies will help to address some of the most difficult but fundamental questions we have about the Earth, including: How deep within the Earth does life live? What limits the growth of life in these extreme environments? How large is the subseafloor biosphere, and what role does it play in the carbon cycle? We will test this inert non-toxic material by attaching it to temperature probes and placing the probes in direct contact with high-temperature hydrothermal fluid for 2-3 weeks. We will examine the material before and after vent fluid exposure using fluorescence microscopy, and evaluate any changes in its physical and optical properties. The goal of the second component is to characterize the range and stability of an optical multi hop sensor network. Sensor networks employ a spatially distributed array of communicating nodes, in which each node collects and transmits data to its neighbors in a web-like fashion. Sensor networks allow scientists to monitor dynamic phenomena over an extended area simultaneously. Optical multi-hop networks will form an important part of the communication backbone for distributed, underwater sensor data collection to help monitor ocean fine-scale phenomena. Such networks can be joined by passing ROVs, AUVs, or other sensors (like those used to monitor the tracers described above) to relay data to each other or onto a cabled observatory or surface buoy for real-time reporting. On this cruise, we will test two optical modem modules deployed multiple times at varying distances apart along a cable. The data will be statistically combined in order to model and plan for future sensor network missions.