Date of Award

2019

Degree Type

Thesis

Degree Name

Master of Science in Ocean Engineering

Department

Ocean Engineering

First Advisor

Chris Roman

Abstract

Due to the harsh environment and inaccessibility of the deep-sea, most oceanographic equipment is rated to sample above the hadal region (6000 meters and below). A few deep-sea landers and piloted vehicles have ventured into deep ocean trenches to sample at the ocean floor, but the hadal water column remains under-sampled. A full ocean depth profile and hadal samples can provide information on ocean circulation, deep-water mixing, trench overturning rates, and the ocean environment.

The Platform for Hadal Autonomy and General Experimentation (PHAGE) is a full ocean depth profiler rated to 11 km. Designed around a 24 bottle CTD rosette, PHAGE is an untethered system that autonomously descends to the bottom of the ocean to profile with a CTD and sample the water column at a relatively low cost. Taking only 24 water samples spaced over the entire ocean depth has a high the likelihood of missing important features of the water column (i.e. thermocline or oxygen minimum). An adaptive sampling software was developed for analysis of the water column to identify and sample the desired features while PHAGE is underway. Because the system is untethered, acoustics are the only form of communication. Acoustic ranges were used to track the submerged vehicle using a range-only tracking technique.

In September 2018, the vehicle was tested to 8377 meters in the Puerto Rico Trench. PHAGE was able to sample bottom water and generate full ocean depth profiles. An overview of PHAGE and a performance analysis are presented throughout this thesis to help with future deployments.

Available for download on Saturday, October 19, 2019

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