Demonstration of wireless data harvesting from a subsea node using a “ship of opportunity”

Abstract

The optical communications group at Woods Hole Oceanographic Institution has demonstrated wireless optical transmission of video for the purpose of performing tasks using the ROV Jason as well as the offload of data from a seafloor instrument to a surface vessel using a lowered optical telemetry system (OTS). Both of these efforts are based on the same optical telemetry concept designed for high bandwidth, deep water, and 100+ meter range operations. To demonstrate the basic capabilities of data harvesting from a seafloor node, we installed optical modems at two seafloor CORK borehole observatories (CORK 857D and CORK 1025C) in the northeast Pacific in 2012 using ROV Jason. The seafloor optical modems enable remote data offload directly to the surface without the need for a submersible. The original concept of the demonstration was to revisit the installed CORK optical modems after a year-long deployment in order to test an OTS lowered by wire from a ship and to utilize the autonomous underwater vehicle (AUV) Sentry for a remote data off-load. Due to scheduling issues related to the submersible Alvin program and shiptime, we were unable to field the experiment as first conceived. However, we were fortunate to obtain a short amount of shiptime on a research vessel with modest capabilities in terms of station keeping - i.e., no dynamic positioning, no bow thruster, and no ultrashort baseline (USBL) navigation - in order to download data after a year-long deployment. In this paper, we report on the successful data harvesting mission from two seafloor CORK observatory nodes using a “ship of opportunity.” The lessons learned from this exercise will inform our next scheduled trip in 2014 to use AUV Sentry or similar “mobile platforms” for future remote data downloads.