The Mariana Trench is having a moment of fame--again.
Fifty-two years after the first and only manned expedition to the deepest spot in the world's oceans--a daring dive by two men in an eccentric vehicle called a bathyscaphe--several teams are vying to be second. With cutting-edge submersibles, they're aiming to send a human being to the bottom of that 11-kilometer-deep crevasse.
In our March issue, we profiled the Virgin Oceanic team, which is led by British billionaire Sir Richard Branson and California adventurer Chris Welsh. They hope to attempt a Mariana dive before the end of the year. But it looks very likely that another team will beat the Virgin Oceanic folks to the bottom. Today James Cameron, director of films like The Abyss and Titanic, finally unveiled his super-secret sub, and announced that he'll try to reach the Mariana Trench seafloor this month. That's his sub, which he has named the DeepSea Challenger, in the picture above.
Like the Virgin Oceanic submersible, Cameron's vehicle is also a one-seater, which means that Cameron is on track to become the first human being to take a solo dive in the deepest abyss.
We should note that none of the people involved like to characterize this as a "race to the bottom," even if that's how the rest of the world sees it. Both teams are working with research scientists to bring back samples and recordings from the unexplored seafloor, and both groups say the more vehicles down there, the better it will be for science.
From a technology perspective, it's interesting to review the differences in the designs of the two teams' submersibles. The Virgin Oceanic sub looks like a stubby-winged plane, and will use hydrodynamic forces to pull it down through the water (the same way aerodynamic forces pull an airplane up). In a radical departure from submersible convention, the Virgin sub uses a cylindrical pressure hull made of carbon fiber for the crew compartment, and sports a large quartz dome on the front. See below:
In contrast, Cameron's sub uses a traditional steel sphere for the crew cabin; spheres are the most pressure-resistant shape, and since we understand the properties of steel quite well, it's a safer, if tamer, choice. (The pressure at the bottom of the trench is about 110 megapascals, or about 16 000 psi.) The crew cabin is embedded within a vehicle that Cameron described as a "vertical torpedo," which will fall straight down through the water.
Other components of the two teams' subs are similar: They both use steel plates for ballast to weigh them down during the descent, and high-tech syntactic foam (an epoxy with hollow glass microspheres) as the buoyant material that will bring the subs back up to the surface after they drop their ballast on the seafloor.
Cameron won't have a great view from inside the crew cabin, since it sports only one small porthole. But to no one's surprise, the director's sub is decked out with LED arrays and cameras. Cameron has announced that the Mariana Trench dive will form the basis of two documentaries, one in 3D that will be shown on IMAX screens, and another to air on the National Geographic channel.
DeepSea Challenger Photos: Mark Thiessen/National Geographic; Virgin Oceanic Graphic: Bryan Christie Design