Water pressure in the deep sea makes human exploration of the ocean difficult. Special equipment such as a scuba regulator is needed to help humans withstand the pressure at even the average depth of the ocean—which is 380 times greater than at the surface, according to the U.S. National Oceanic and Atmospheric Administration.
Alvin, the first U.S. human-operated vessel dedicated to scientific research, made it possible for humans to dive for up to nine hours at 4,500 meters. Alvin was developed in 1964 by a research team led by geophysicist Allyn C. Vine at the Woods Hole Oceanographic Institution (WHOI), in Falmouth, Mass.
Thanks to Alvin, scientists were able to study the effects of pressure on seafloor microbes and discovered hydrothermal vents that help regulate ocean chemistry and support ecosystems.
In addition to scientific research, Alvin conducted several expeditions for the U.S. Navy. During its first major deployment in 1966, the vessel was sent to search for a hydrogen bomb that accidently was dropped in the Mediterranean Sea after a U.S. Air Force bomber and a tanker collided over Spain. It took Alvin two months to find it.
The submersible, which is still used today, has been commemorated with an IEEE Milestone. The IEEE Providence (R.I.) Section sponsored the nomination. Due to the COVID-19 pandemic, the dedication ceremony is still being planned.
THE NECESSARY PUSH
Although Alvin wasn’t the first human-operated underwater vehicle, its predecessors were large and difficult to maneuver. In a 2015 interview with the WGBH Forum Network, Dudley Foster, an engineer who worked on Alvin, described the previous submersibles as “blimps.”
During a 1956 symposium about deep-sea exploration held in Washington, D.C., the U.S. Office of Naval Research made a presentation about one of the submersibles: Trieste. After the conference, the research office sent a delegation, including Vine, to Italy to see the 18-meter-long, 45-tonne vehicle. The U.S. Navy purchased Trieste in 1958 to conduct research. When in 1960 it made an expedition to Challenger Deep, the nethermost point of the Mariana Trench, it was the first time a manned or unmanned vessel reached the deepest known point of Earth’s oceans. But Trieste proved “too large and cumbersome for routine operations throughout the oceans,” according to a 2014 Eos article.
Vine and his research team, the WHOI Deep Submergence Group, in collaboration with the research office, requested bids to build a smaller and more maneuverable submersible. General Mills, in Minneapolis, secured the contract with a bid of US $498,500, according to the Eos article.
Alvin, which was named after Vine, was designed by General Mills engineer Harold “Bud” Froelich. The vessel’s frame was built using syntactic foam, which was buoyant and strong enough to withstand extreme pressure. Alvin weighed 15 tonnes and was about 7 meters long, according to WHOI. The vessel was completed in 1964.
Propulsion equipment was housed in the back of the vehicle along with three lead-acid batteries and five buoyancy spheres, which controlled its vertical movement. Electrical and fiber-optic connectors and cables were encapsulated in oil-filled hoses and boxes, making them waterproof. To help Alvin withstand the high pressure, the back was open so that seawater could flow around the equipment.
The researchers and pilot sat in a sphere at the front of the submersible. The steel sphere, which was about 2 meters in diameter and had three plexiglass windows, housed life-support systems. In an emergency, the sphere could detach and float to the surface. Alvin also had landing skids so that it could sit on the ocean floor.
Equipment in the sphere controlled the submersible as well as two robotic arms and cameras that were mounted on the front. The arms could be fitted with probes and tools to take samples of sediment and marine life. A specially designed insulated box ensured that collected samples weren’t ruined by changes in water temperature or pressure, according to Dudley. Alvin’s still cameras used thallium iodide lights to illuminate the seafloor—which, he says, emitted a green light rather than white light because the former travels through water better and allowed for brighter photos.
Alvin sank about 1,500 meters to the bottom of the ocean in 1968, 217 km off the Massachusetts coast. It was recovered a year later.Woods Hole
Alvin’s first major scientific discovery happened by accident in 1968, when the submersible sank about 1,500 meters to the bottom of the ocean. A cable snapped while the vehicle was being lifted out of the surface ship that had carried it 217 km off the Massachusetts coast to look for whales. The crew escaped unharmed, but the food they brought for lunch sank with the ship.
When Alvin was recovered a year later, the food—which included soup, bologna sandwiches, and apple slices—was “essentially intact,” according to the Milestone’s entry on the Engineering and Technology History Wiki. Researchers investigated why the food didn’t decay as it would have on the surface. They discovered that the pressure suppressed the growth of the surface bacteria that was in the food.
Another important discovery—the existence of hydrothermal vents—was made on a research trip led by oceanographer Jack Corliss in the Galapagos Rift, located in the South Pacific.
“Hydrothermal vents spew poisonous superheated gas and metal-laden water, and yet scientists saw creatures such as giant tube worms, clams, and mussels thriving in the environment,” says a 2020 Medium article about Alvin.
Corliss saw that the ecosystem was isolated from sunlight and soon after, according to the 2020 article, theorized that life might have first emerged around such vents.
“Corliss believed that hydrothermal vents contained all the conditions necessary for the origin of life on Earth,” the Medium article states.
During the past six decades, Alvin’s equipment has been upgraded many times. It now includes an acoustic navigation system and high-resolution digital cameras. In May a new video system, robotics, and new syntactic foam modules were installed. The modules allow Alvin to reach a depth of 6,500 meters, according to the ETHW entry.
The Milestone plaque is to be displayed outside the Smith Laboratory at WHOI. The plaque reads:
In 1965 the U.S. Navy commissioned the Woods Hole Oceanographic Institution’s deep-sea submersible, Alvin. From 1974 to 1984, Alvin’s engineers developed acoustical navigation (ALNAV), communications, photography, lighting, and life-support systems specifically intended for the deepest oceans. It became one of the world’s most important deep-sea scientific instruments. Alvin discovered effects of pressure on seafloor microbes, and Alvin’s study of hydrothermal vents revolutionized our understanding of life’s origins.
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