ALOHA Cabled Observatory
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ALOHA Cabled Observatory
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Station Aloha Resource Page
More than 35,000 km of fiber optic telecommunication cables installed in the Pacific Ocean alone have been or will be retired shortly, replaced by systems with orders of magnitude more communications bandwidth. While these systems (SL-280 and SL-560) are obsolete for commercial use, they have considerable potential value for use as ocean observatory infrastructure. A DEOS/NSF committee on cable re-use concluded in September, 2003, that there are no fundamental engineering issues that would prevent cost effective use of these retired cables (Link to DEOS Report). A workshop of former AT&T cable engineers at Rutgers in 2003 endorsed the concepts of cable re-use and provided many suggestions on how to proceed (Link to 280-560 Report). Unfortunately, the Ocean Observatory Initiative, ORION, and the NSF had already settled on a three-part ocean observatory initiative (regional observatory utilizing NEW cable, global observatory buoys, and costal observatories) before it was realized that the huge retired cable resource would be available, and the various stake-holders were not willing to consider cable re-use as part of the OOI. Although the SCOTS Report recognized the great potential value of re-use of retired cables, this potential has gone largely ignored. Each of these systems had a cost of more than $1 billion to install, and all are still within their original design lifetimes. We strongly believe that this refusal to consider cable re-use to any significant level is a serious mistake. In an attempt to partially rectify this situation and to demonstrate the capabilities of these systems, we plan to install a minimal cable re-use observatory at Station Aloha to augment the HOT program by providing researchers with continuous power and real-time data link to shore utilizing the retired HAW-4 SL-280 system.
System Characteristics:
The Aloha Cabled Observatory will provide users with wet-mate connectors on the ocean floor that can be utilized in several ways. Researchers can connect to the system using an ROV and be assigned a 10Base-T channel with an IP address and an electrical circuit protected by a programmable circuit breaker to protect the instrument and the infrastructure. Both 48 and 400 Volt circuits will be available depending on how far from the observatory the user experiment will be placed and how much power is needed. Alternatively, the user can connect a simple RS-232 or RS-422 communications circuit to the observatory, or an acoustic link that communicates acoustically with an autonomous instrument. While experimenters will need to coordinate closely with the observatory infrastructure management, the design should allow a wide range of experiments to be accommodated. The limiting resource as the observatory fills up is likely to be electrical power. When this occurs, the observatory power system can be replaced with a system capable of delivering more power (up to about 2 KW) and/or more bandwidth. Multiple nodes utilizing other channels and other fiber pairs in future observatories on HAW-4 or similar systems are certainly possible, The constant-current power system makes it relatively simple to add other nodes in series and to control power allocation. As the cables are already installed and operational, the high costs of shore connections and shore station infrastructure are already paid, except for a modest lease cost for use of the cable station
Page Last Modified 08/10/2007
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