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Dive to the Abyss

Exploring Seascapes 1 | 2

This elite fleet of deep-sea subs don't just sink. They bristle with robotic arms, suction tubes, cameras, and scientific instruments that allow scientists to collect samples and document the interesting -- and often weird -- undersea world. They also sport sophisticated buoyancy and propulsion systems that allow them to dodge around sunken peaks and navigate flooded canyons. Most importantly, these craft allow people to see this hidden universe for themselves. "The human presence is critical," says Daniel Fornari of the Woods Hole Oceanographic Institution in Massachussetts, which operates Alvin. "People can react to things they see, make decisions, and generate knowledge" that might not be obvious to mechanical sensors.

A new breed of remotely-operated vehicles (ROVs), however, may replace manned subs for many tasks. These craft are typically tethered to their mother ships by long cables, and controlled by "video jockeys" on the surface watching a television screen. Unlike their crewed counterparts, however, ROVs don't need to make room for bulky -- and expensive -- life support systems, freeing up room for more scientific gear. And they aren't limited by human frailties, making it possible to run longer missions.

ROV pilots don't get "cramped, damp, and cold," says Marcia McNutt, head of the Monterey Bay Aquarium Research Institute in Moss Landing, California, a pioneer in ROV technology. And the craft "never get hungry, never run out of power -- and nature never calls," she adds. As a result, some ROVs can collect data round the clock -- while manned subs can spend as little as a few hours on the bottom, and hours more getting to and from their destinations.

Such technical challenges partly explain why a manned craft has never repeated Walsh and Piccard's expedition to the Challenger Deep. But an ROV has: In 1995, Japan's Kaiko returned to the Marianas Trench, bringing back samples of some of the deepest-living animals -- small crustaceans -- ever collected.

Now, deep-sea explorers are debating whether they should build new manned craft that might build on such discoveries -- or concentrate on unmanned vehicles, including new computer operated vehicles that wouldn't need to be tethered to a mother ship. Either way, these inner space adventurers are united behind a common rallying cry: "Onward! Downward!"

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Exploring Seascapes
How technology is helping divers

Into The Deep
Uncover the mysteries of the abyss

Interview
Meet a deep-sea diver

Resources
Find out more about deep-sea exploration
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