Whales, seals, and other marine mammals seem to do alright in the chill waters of the arctic seas, so the US Navy is developing a type of "artificial blubber" to allow divers to work in freezing conditions for hours on end. Sponsored by the Office of Naval Research (ONR), the collaboration between MIT and George Mason University uses an off-the-shelf wetsuit permeated with inert gases to triple a diver's resistance against the threat of hypothermia.
Though the aqualung and other underwater breathing apparatuses have introduced thousands of people to the exhilaration of swimming beneath the sea, and have created whole new industries, they have also made it clear that human beings are definitely not creatures of the ocean. And it isn't simply a matter of needing air tanks to go diving. There's also the fact that the human body is ill adapted to swimming in anything but the warmest of waters for any length of time.
To protect themselves from hypothermia, divers wear different kinds of protective suits depending on how cold the water is. The most common of these is the ubiquitous wetsuit, which uses a combination of expanded neoprene and a thin layer of water warmed by the diver's body to provide protection in waters between 10° and 25°C (50° and 77°F).
The wetsuit is a very simple and successful system, but it's limited in terms of time and temperatures, so the ONR team led by MIT's Michael Strano and Jacopo Buongiorno are working on a simple way to tweak wetsuits in order to provide better protection – apparently delivering up to three times the endurance in cold temperatures.
The modification involves replacing the air trapped in the neoprene foam that provides heat insulation with heavy, inert gases, such as xenon and krypton, which make the neoprene act like fat-concentrating blubber. This is done by putting an ordinary neoprene suit into a bespoke pressure tank the size of a beer keg and pumping in the inert gases. After several hours, the gas permeates the suit, forcing the air out.
According to ONR, this makes the suit effective at 10° (50° C) for hours instead of minutes. The treatment isn't permanent as the gases leak out over 20 hours, but the team points out that this is much longer than the time divers spend in the water. However, the suit can be pretreated before a cold-water dive and then sealed in a plastic bag until needed. The gas does not leak out until the bag is opened.
So far, the suit has only been tested in the lab, but Strano and Buongiorno plan to conduct dive demonstrations with Navy and civilian divers.
"This kind of research is especially important as more Arctic sea lanes open up and the Navy increases its readiness to operate in that part of the world," says Maria Medeiros, a program officer in ONR's Sea Warfare and Weapons Department. "Whether it's special operations; search and rescue; or ship repair, maintenance and salvage, finding ways to increase divers' time and effectiveness in the ice is a priority."
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