The new life of the research submarine Alvin

As incredible as it may seem, we have more information about the surface of other planets than we do about what lies in the depths of the oceans. Sending a man into space is undoubtedly complex, but exploring the abyss is no less, and, in many respects, the environment to be faced is even more aggressive than the cosmic void. Enormous pressures, low temperatures, darkness, and strong currents are some obstacles that must be overcome to explore the seabed. Physiological limits restrict the depth to which a diver can go. Even the most advanced techniques of commercial saturation diving allow divers to reach a maximum of a few hundred meters, almost nothing compared to the thousands of meters of the ocean floor. The alternatives are to use robots or a submarine. Underwater robots, commonly called ROVs (Remotely Operated Vehicles), are now widely available for commercial purposes, such as offshore work and scientific research. Their limitation is that they only allow telepresence, which, although important, is not entirely equivalent to exploring the underwater environment “in person.” Submarines, conversely, are mainly the domain of military technologies with very few exceptions. The number of research submarines that can go so far as to explore the ocean’s depths can be counted on the fingers of one hand.

One of the most famous and technologically advanced research submersibles is the Alvin (an acronym for Allyn Vine, geophysicist and pioneer of deep diving technologies) supplied to the USA’s Woods Hole Oceanographic Institution (WHOI). Built in 1964, it underwent a complete system upgrade in 2014 with a total investment of $41 million, jointly funded by the National Science Foundation and WHOI.

The Alvin can operate up to a depth of 4500 meters, potentially reaching 6500 meters in the near future.  A pilot and two researchers are hosted inside a titanium sphere of about two meters in diameter, weighing almost five tons with seven centimeters thick walls, and incorporated in a chassis complete with thrusters, lights, high-definition cameras, and manipulators. Through five portholes with a diameter of about 20 centimeters, scientists will have a unique “camera with a view” that can reach 98% of the ocean floor in terms of depth.

One of the biggest challenges for the design of the Alvin is to compensate for the overall weight of the submersible, which exceeds sixteen tons, to make it maneuverable in the water. For this reason, a unique material has been developed as microscopic glass spheres immersed in epoxy foam, creating a substance capable of withstanding the enormous ocean pressures while simultaneously providing buoyancy to the system. The foam is shaped to form an outer shell for the titanium sphere and a series of panels around the submersible frame. For safety reasons, 100% of the material used has been subjected to rigorous pressurization tests that confirm its resistance well beyond the maximum operating depth provided with a margin of 50%.

Still, on the subject of safety and redundancy, all the leading systems of the submarine are duplicated with a perfectly symmetrical port and starboard side. Even in a catastrophic failure of one part of the system, the pilot can still operate the submarine using the other half. Passengers are also instructed in emergency procedures, and in the unlikely event that the pilot becomes incapacitated, they can begin the surfacing process on their own. In case of need, several parts of the Alvin can be abandoned at sea without compromising the integrity of the sphere and the crew’s survival. Thrusters, batteries, manipulators, and ballast are prepared for emergency detachment in case they become entangled in structures on the seabed, such as cables or nets, or to provide greater buoyancy to the submarine.

Alvin is powered by a battery system that guarantees up to eleven hours of autonomy while diving. Considering that three to four hours are required for descent and ascent, scientists have about six to seven hours to conduct their research. New batteries will be used shortly to increase the autonomy in immersion and allow the use of higher energy consumption systems such as, for example, more powerful lights for high-quality videos.

Among the most important discoveries made thanks to the use of Alvin is the identification, in the 1970s, of imposing geothermal structures on the ocean floor with colossal chimneys emitting a flow of water at very high temperatures (over four hundred degrees Celsius) and which host unique life forms that are based on the use of chemical compounds of sulfur. These structures are hypothesized to be the origin of life on Earth and among the primary ocean minerals sources.

In 1986, Alvin was used to explore the wreck of the Titanic lying on the bottom of the North Atlantic at a depth of almost four thousand meters. A small ROV named Jason, controlled by the crew of the Alvin, has penetrated inside the wreck, providing unique images that will inspire director James Cameron in the production of the colossal “Titanic.”

To date, Alvin has completed about 5,000 dives, allowing thousands of scientists to research in an otherwise unreachable environment. The very few qualified pilots are in stark contrast to the high number of passengers. In the entire history of the Alvin, only 38 men and one woman have completed the training necessary to conquer the coveted command seat. By comparison, there were 75 Space Shuttle pilots. Today, the Alvin is in full operation, and who knows what discoveries can be made thanks to this “fifty-year-old young man” who still enjoys exploring the ocean floor.