iPlex Lunch spring-2016

Autonomously Deployable Deep-ocean Seismic System - Communications Gateway for Ocean Observatories

In this talk, I describe an autonomously deployable, communications gateway designed to provide long-term and near real-time data from ocean observatories. The key features of this new system are its abilities to telemeter sensor data from the seafloor to shore without cables or moorings, and to be deployed without a ship, thereby greatly reducing life-cycle costs. The free-floating gateway uses a Liquid Robotics wave glider comprising a surfboard-sized float towed by a tethered, submerged glider, which converts wave motion into thrust. For navigation, the wave glider is equipped with a small computer, a GPS receiver, a rudder, solar panels and batteries, and an Iridium satellite modem. Acoustic communications connect the subsea instruments and the surface gateway while communications between the gateway and land are provided by the Iridium satellite constellation. Wave gliders have demonstrated trans-oceanic range and long-term station keeping capabilities. A shallow tow body houses a WHOI acoustic micro modem and a Benthos low frequency, directional transducer. A matching modem and transducer are mounted on the ocean bottom package. Tests of the surface gateway in 4350 m of water demonstrated an acoustic efficiency of approximately 396 bits/J. It has the ability to send 4 channels of compressed, 1 sample per second data from the ocean bottom to the gateway with an average power draw of approximately 0.15 W and a latency of less than 3 minutes. I present results from several short-term OBS tests off-shore La Jolla, at water depths of 1000 and nearly 4000 m. Ultimately, the package will be outfitted for two-year operations. Such data from presently unobserved ocean sites are critical for scientific research ranging from Earth structure to monitoring earthquakes and tsunami.