NOAA's Teacher-at-Sea Program

John A. Duff, J.D., LL.M., M.A.
 

As long as humans have sailed the oceans, they have focused their attention on the state of the seas that they could feel and see. Even today, most who make their living or make their way across the oceans know precious little about the activity that is taking place below them. In addition to the myriad marine life that inhabit the seas, the earth itself is going through a continuous regenerative process. New crust is formed and the seafloor spreads as old crust is driven back under the shifting plates of the planet.

In the mid-1980s scientists discovered significant volcanic and hydrothermal vent activity off the coast of Washington and Oregon in the vicinity of the Juan de Fuca ridge, a submerged mountain range-like area that includes an enormous caldera of a long dead underwater volcano. Over the course of the last thirteen years, NOAA research ships have served as the platforms used by scientists to explore these areas to examine new volcanic activity and assess the very nature of the earth's fundamental workings. The NOAA VENTS Program is an ongoing study of the hydrothermal plumes and the associated physical, geological, chemical, and biological processes taking place thousands of feet below the surface of the ocean.

In July, an oceanographic expedition conducted from the NOAA research ship Ron Brown served as the floating laboratory for NOAA's VENTS '98 operations. As a participant in the NOAA Teacher-at-Sea Program, I joined the crew of the Brown to take part in the effort designed to take the pulse of the hydrothermal activity along the Juan de Fuca Ridge. Chief Scientist Ed Baker of the Pacific Marine Environmental Laboratory coordinated the effort and explained succinctly, "basically we're trying to learn how the ocean and the earth's crust interact."

The efforts to learn more about these interactions include the deployment and retrieval of a wide range of scientific equipment designed to record the seismic activity, the speed and direction of the deep sea currents, the temperatures, and the chemical composition of the hydrothermal vent areas. In February, the area experienced significant volcanic activity and this mission would be the first opportunity to recover instruments in place at that time.

Retrieval of these instruments is a combination of science, luck and skill. Instruments deployed earlier were marked and mapped so that upon returning, the ship could come within a few hundred meters and thousands of feet above to retrieve them. An electronic transceiver is lowered overboard to "talk" to the coupling device on the mooring line. Once the shipboard device locates the instrument line, a signal is sent to release the buoyed mooring line from the weight anchoring it to the seafloor. If the device has not been compromised by the seismic activity in the area or any of a dozen other possible problems, the release begins its slow ascent to the surface. At this point, it becomes a contest between crew members as to who can first spot the buoy as it pops to the surface with its prize attached.

Most of the data from those instruments would not be analyzed until the crew got back into port, but the onsite monitoring efforts of the mission allowed us to take a "look" at the activity that was taking place thousands of feet below us as we towed instruments over the area. A conductivity-temperature-depth instrument (CTD) equipped with a series of torpedo shaped tubes was lowered by a cable tow within a few meters of the ocean's bottom and each bottle could be "triggered" to collect water samples at given points. The locations could be selected by an operator monitoring readout that communicated water temperature, salinity, and particulate matter in the water column. Upon retrieval, the contents of each bottle were tapped to collect samples of dissolved helium isotopes, pH level, salinity and other chemical and biological compositions.

As a part of the scientific crew, I was able to take the controls on the CTD operation. I issued instructions to the winch operator as to speed and depth of the CTD. Traveling at about two knots per hour with three thousand feet of cable played out towing a device over submerged valleys, ridges and the occasional underwater mountain is akin to flying over a mountain range trailing a piece of heavy duty scientific equipment far below and behind. The challenge is to get within a few meters of the bottom in order to collect samples without slamming the device into an underwater mountain or bouncing it off the seafloor.

My duties on the second half of the cruise moved onto the deck of the ship where I helped to rig the CTD with its bottles, guide the device on and off the ship and collect water samples. As I peered over the CTD as it was deployed into the sea, I noticed the mouths of the tubes opened wide like a nest of hatchlings eagerly waiting to be fed - an interesting metaphor for the scientists eager to see what scientific nourishment might be gleaned from the effort.
 

University of Mississippi