nance purposes, one to two dedicated research vessels or workboats with ROVs will be required to support an observatory consisting of some two dozen nodes.

CURRENTLY AVAILABLE TECHNOLOGY

Cable—The current generation of commercial optical undersea cables can satisfy all anticipated observatory data requirements. These cables contain up to eight or a few dozen optical-fiber pairs for long (greater than approximately 300 km) and short systems, respectively, and can provide data transfer rates on the order of 500 Gb/s per fiber pair. Early-generation, commercial cable systems that may soon be retired have a total cable capacity of approximately 500 Mb/s to 2 Gb/s. Such cables can meet many observatory data needs, but it is not clear that they are suitably located or that power capabilities will be sufficient.

Connectors—Undersea mateable connectors suitable for providing electrical connections between the nodes and specific science-experiment equipment are currently available.

Installation and Maintenance Technology—Currently, ships and ROVs that are suitable for installation and maintenance of cabled observatories exist within industry and UNOLS. Although it is likely that UNOLS ship capabilities would be adequate for many maintenance tasks, the additional burden on the already stressed ROV fleet will need to be addressed.

FUTURE DEVELOPMENTS NEEDED

Physical Design of the Cabled Observatory Nodes—Substantial engineering development will be required for the design and packaging of the power conditioning, network management, and science-experiment management equipment to be placed at the observatory nodes. An important component of this development is the design of the thermal management system required due to the relatively high internal power dissipation. In order to meet the necessary specification for high system-operational time (versus downtime), low repair costs, and overall equipment lifetime, significant trade-offs will have to be considered between the use of commercially available and custom-built equipment.

Sensor, Power, and AUV and ROV Technology—The capabilities needed for sensors, power, and AUV and ROV technology are discussed in Chapter 4.



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