The opportunity of suffocating in an icy steel coffin several hundred meters below the ocean's surface is not high on the list of reasons most young men join the Navy. The lingering deaths endured by the survivors of the initial explosions aboard the Russian submarine Kursk are testament to the need for highly-developed undersea rescue systems. With the Russian catastrophe fresh in their minds, both the Americans and Europeans are working hard to come up with a more certain way of retrieving trapped sailors. The logistical and engineering challenges in rescuing personnel from a damaged submarine are colossal. 615 people have lost their lives in submarine accidents since the end of World War 2.
There are two main approaches for getting people out of a damaged sub. The first is for the personnel themselves to make their way to the surface using a range of breathing gear and the vessel's escape hatches. The second course is for a rescue vessel to mate with the crippled sub and transfer the stranded personnel to the surface. This can either be a manned or unmanned submersible or some sort of unpowered pod. The USA for example, has two Deep Submergence Rescue Vehicles (DSRV's). One is always in the Atlantic and one in the Pacific. They have a crew of four and can hold a further 24 victims. There are also Submarine Rescue Chambers (SRC's), which are pressurised diving bells designed to be lowered onto a submarine from any ship with a large enough crane. They can transport 6 evacuees to the surface.
Both systems rely on a skirt that covers the hatch of the target submarine. When sealed to the hull, this acts as an airlock, pumping out water and equalising pressure between the two vessels before the hatches are opened. Both systems require some support from divers and/or smaller, remotely-operated vehicles (ROV's). In the case of the SRC's, cables need to be tethered to the damaged sub so that the chamber can stay on target. There are many problems with these approaches, which apart from the robotic angle, has changed little in 50 years.
The newest addition to the US Navy's rescue equipment is known as the Hardsuit 2000. This robotic-looking creation is what's known as an Atmospheric Diving Suit, or ADS. Its tough shell removes the need for boosting internal pressure. Just like on a submarine, the occupant is breathing air at normal surface pressures. That means that when he returns topside, he can step out of the suit without needing any decompression treatment. Once a disabled submarine has been located, a Hardsuit 2000 team could be deployed to the site within hours and begin conducting an initial survey, providing the rescuers with video, sonar and personal observations. The primary task of the divers would be to clear debris from the submarine hatch, remove the hatch fairing and connect the downhaul cable for the SRC. The suit has 16 (four in each limb) hydraulically compensated rotary joints, which allow the pilot to physically move the arms and legs of the suit. Manually operated fingers at the end of each hand pod allow him to grasp and manoeuvre objects. A pair of 2.25 HP thruster modules are controlled by footpads within the suit, permitting the pilot to "fly" from point to point or maintain station within a current. The onboard life support system will allow it to work at depths of 600 meters for up to six hours, with additional emergency life support for up to 48 hours.