SUBMARINE SAFETY: Spending significant amounts of time underwater requires substantial effort to preserve the safety of a submarine and its crew. Nuclear-powered submarines can spend months underwater and therefore require systems to maintain a livable on-board environment. One way to generate oxygen is by the electrolysis of water -- using electricity to break down water into hydrogen and oxygen. The air in the vessel also must be filtered to remove carbon dioxide that builds up. Many of today's models are designed with multiple hulls, which allow designers to combine the best shape for streamlined travel with the best shape for withstanding the pressure of deep water.
ABOUT THE BENDS: Decompression sickness occurs when bubbles of dissolved gases concentrate in the blood. It can occur when divers resurface too quickly to allow their bodies to acclimate to changing pressure conditions when returning to the surface. Joint pain is one of the major symptoms, but decompression sickness can also affect the skin, brain, inner ear, nervous system, and lungs. Divers typically plan their ascents carefully to avoid the most severe symptoms, which include paralysis and death.
The American Physical Society contributed to the information contained in the TV portion of this report.