Monterey Bay Aquarium Research Institute

Brewer Expedition
August 10 - August 17, 2006

August 13, 2006
Third ROV Dive: Coring - Take Three


An unfortunate reminder of the 800+ meters that had to be removed due to damage to a section of the outer casing.

Yesterday evening was plagued with difficulties. Immediately before we attempted to retrieve the ROV from the day’s dive, a serious problem became apparent: the outer casing of the umbilical cord, the lifeline of the ROV, had been unraveled by a misalignment of the pulley system. With this degree of damage, the fiber optic/power cable in its current state would be too great a liability for future dives. Therefore, nearly 900


An example of a cylindrical coring sample taken during today’s ROV dive...
meters of cable had to be removed and a new cable end needed to be created in a twelve-hour process that took until 10am this morning.

In addition, increasing winds of up to 30 mph have made the seas more turbulent and prohibited yesterday’s AUV mapping dive. The rougher seas have continued through today, with increased rocking of the boat. The ROV dive went as planned, however, in hopes of finding an effective coring method to use for the majority of the remainder of the experimentation in situ and for collection for the lab.

In contrast to the above-mentioned problems, today’s experiments went exceedingly well. With some improvement to the orientation of the serrating teeth on the end of the coring tool and an adjustment of the placement of the control cables, the coring process became significantly easier, enabling us to collect three perfectly cylindrical samples. The first sample was from the top of the outcrop and contained the yellow infiltrating oil. The second was from a softer, purer section of the outcrop, which was used to analyze the


Some fragments of collected methane hydrate aflame on our grill on the back deck.
chemical composition of a cross-section of the exposed hydrate mound by shining the laser at various points along its length inside the Pyrex viewing chamber. Finally, the third sample was taken from the same location as the second and heated with the heat probe while in the Pyrex chamber in order to study its dissociated form into its component gases.

Finally, to conclude a successful day, we were fortunate to serendipitously discover a sizable fragment of hydrate that had broken off the seafloor and wedge itself under the ROV’s light bar and survived the temperature and pressure changes all the way to the surface. While a majority of the specimen was preserved in liquid nitrogen for future lab study, the remainder was left over for our amusement. The highlight of which was our setting the methane/ethane-containing structure aflame on the grill with a simple cigarette lighter. Weather permitting, we will hopefully continue to witness more remarkable successes on this expedition.


 

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