Field Log: June 2: Sentry and Jason

We’ve collected several more sets of water samples, gravity cores, and had a couple more joint autonomous underwater vehicle (AUV) Sentry and remote operated vehicle (ROV) Jason deployments. All the work through tomorrow is taking place in the northern section of the Escanaba study area, nicknamed “NESCA.”

This fish was observed inspecting sediment push-core samples during an Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition dive.
This fish was observed inspecting sediment push-core samples during an Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition dive. Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 1.4 MB).
The Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition team experienced dead calm seas on June 1, kind of eerie.
The Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition team experienced dead calm seas on June 1, kind of eerie. Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 948 KB).
An outcrop of hydrothermal rocks that presents colorful red and yellow tones from the iron sulfide under the outer layer of organic and sedimentary debris. Imaged during an Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition dive with remotely operated vehicle Jason.
An outcrop of hydrothermal rocks that presents colorful red and yellow tones from the iron sulfide under the outer layer of organic and sedimentary debris. Imaged during an Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition dive with remotely operated vehicle Jason. Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 3.2 MB).
Cross-section of a vent chimney collected during an Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition dive, about 18 centimeters (7 inches) across. Contains the iron-rich mineral pyrrhotite.
Cross-section of a vent chimney collected during an Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition dive, about 18 centimeters (7 inches) across. Contains the iron-rich mineral pyrrhotite. Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 1.7 MB).

The dive locations have been centered around “Central Hill” and “Edifice Rex.” The weather has been calm, but we are expecting winds of 20 to 30 knots beginning Friday (June 3) evening and 9- to 11-foot seas by Saturday (June 4). The plan is to head about 50 miles south at that time and begin work in the southern part of Escanaba, called “SESCA.”

Inside of a fluid-conduit collected during the Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition. Scientists think it contains substantial amounts of the iron- and copper-bearing minerals pyrrhotite and chalcopyrite, as well as zinc-rich sphalerite.
Inside of a fluid-conduit collected during the Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition. Scientists think it contains substantial amounts of the iron- and copper-bearing minerals pyrrhotite and chalcopyrite, as well as zinc-rich sphalerite. Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 1.4 MB).
A temperature probe stuck into a hot hydrothermal vent at a depth of 3,219 meters, almost two miles below the surface during the Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition.
A temperature probe stuck into a hot hydrothermal vent at a depth of 3,219 meters, almost two miles below the surface during the Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition. Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 1.3 MB).
During an Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition dive, the team gathered a sample of boiling water (206 degrees Celsius/403 degrees Fahrenheit!) from a hydrothermal vent located at a depth of 3,219 meters, almost two miles below the surface. This image shows the monitor displaying the depth and temperature of the probe. Note that the temperature away from the hot water plume is between one and two degrees Celsius (about 35 degrees Fahrenheit).
During an Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition dive, the team gathered a sample of boiling water (206 degrees Celsius/403 degrees Fahrenheit!) from a hydrothermal vent located at a depth of 3,219 meters, almost two miles below the surface. This image shows the monitor displaying the depth and temperature of the probe. Note that the temperature away from the hot water plume is between one and two degrees Celsius (about 35 degrees Fahrenheit). Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 1.8 MB).

As a reminder, Sentry maps the seafloor while Jason has manipulator claws that can be used to collect seafloor samples. The detailed Sentry maps are incredibly useful when planning out the study areas that Jason will visit. Sentry has a 5-person support team, while Jason has a 10-person team (the Sentry engineers insist that ‘smaller is better’).

U.S. Geological Survey scientists subsampling a clay-rich core during the Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition. They will analyze the core for microbes and small infaunal creatures that live below the seafloor.
U.S. Geological Survey scientists subsampling a clay-rich core during the Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition. They will analyze the core for microbes and small infaunal creatures that live below the seafloor. Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 1 MB).
A layer of turbidite beds capped by a layer of iron-rich volcanic rock seen during an Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition dive.
A layer of turbidite beds capped by a layer of iron-rich volcanic rock seen during an Escanaba Trough: Exploring the Seafloor and Oceanic Footprints expedition dive. Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 2.6 MB).
The front of remotely operated vehicle Jason. There are two arms with manipulator claws, one on the left and one on the right. Samples collected during dives are stored on the platform between the arms.
The front of remotely operated vehicle Jason. There are two arms with manipulator claws, one on the left and one on the right. Samples collected during dives are stored on the platform between the arms. Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 2 MB).
The front of autonomous underwater vehicle Sentry, complete with a mocking smile.
The front of autonomous underwater vehicle Sentry, complete with a mocking smile. Image courtesy of Escanaba Trough: Exploring the Seafloor and Oceanic Footprints. Download largest version (jpg, 1.3 MB).

Jason weighs about 10,000 pounds. However, the full load of the supporting equipment, not including the attached crane, weighs about 100 tons and needs 6 tractor trailer trucks of equipment to support each dive. Sentry is a bit smaller, weighing in at 6,000 pounds, and only needs two large shipping containers to mobilize.

The working time of Sentry and Jason are dictated primarily by battery power. Sentry can operate continuously for about 24 hours, while Jason can operate for about 18 hours.

By Paul Knorr, Bureau of Ocean Energy Management

Published June 5, 2022