James Cameron performs deepest-ever solo sub dive, with a deeper one on the way
Well-known film director and deep-sea explorer James Cameron is no stranger to setting records, but this time, instead of box office gross, he's setting his sights on something more akin to a single-handed lunar landing - a solo trip to the ocean's deepest point, the Challenger Deep in the Mariana Trench off Guam. Billionaire entrepreneur Sir Richard Branson is hard on Cameron's heels but it appears almost certain the genius behind the blockbusters Titanic and Avatar will be the first to get there alone - he just snagged the record for deepest solo dive off Papua New Guinea on March 6th with a depth of 26,791 feet (8,166 m).
Only two people have made it to where Cameron intends to go later this year - Jacques Piccard and Don Walsh - when they co-piloted Project Nekton's (U.S. Navy) bathyscaphe Trieste to the sea's deepest floor on January 23, 1960. In the more than fifty-two years hence, technology has made such tremendous strides that man will once again visit that dark, near-freezing realm roughly 35,800 feet (10,912 m) down, but this time, the results promise to be very different.
When the Trieste landed, it kicked up clouds of silt that rendered photography impossible. Cameron's specially-designed high-tech submersible, the Deepsea Challenger, will be able to hover just off the bottom and capture footage of such high quality, some of it will likely end up in his upcoming Avatar sequel.
Eight years in the making, the unusual, vertically-configured, 24-foot tall (7.3 m), 11.8-ton (10,705 kg) deep-ocean, one-person sub is a technological wonder that incorporates surprisingly little off-the-shelf equipment in its design - for instance, over 1,500 discrete circuit boards were specially designed and built for the sub. The electronics and life support gear-packed 43-inch (109 cm) internal diameter pilot's sphere is located at the bottom end, attached to the rest of the vehicle by flexible polyester straps.
The 2.5 inch (6.4 cm) thick steel-walled sphere (5 inches/12.7cm thick on the Trieste) was successfully land-tested twice to 16,500 psi (1160kg/cm) at Pennsylvania State University - an acceptable safety margin over the conditions it'll encounter in the Challenger Deep, where the ambient pressure could reach 15,965 psi (1122 kg/cm). Envision four Aston Martin DB9 coupes stacked atop every square inch of surface area and you'll get a sense for the crushing weight down there.
Already a veteran of more than thirty deep sea dives, Cameron is obviously not prone to claustrophobia. His cramped seat is surrounded with the screens, devices, switch panels and gauges he'll need to both control the sub and keep himself alive. Two cylinders of compressed oxygen and a carbon dioxide scrubber can keep him breathing for up to 56 hours. A touchscreen readout, similar to those found in some aircraft, will provide constantly updated information and status on most of the 180 systems that will be in operation on a typical dive. He'll control the 12 thrusters that maneuver the sub with a joystick and see what's going on outside the sphere's thick, conical viewport on a viewscreen fed by a Red Epic 5K camera and wide angle lens. The 19-mile (30 km)range of the sub's communication system should easily keep him in contact with the surface.
Outside the sub, four custom designed HD cameras in durable housings specially crafted by the Deepsea Challenger team will capture additional high quality images illuminated by the sub's large seven-foot (two-meter) panel of LED lights. The sub is also equipped with two hydraulic-powered booms controllable from within the sphere. One is equipped with lights, the other, a 3D camera for further imaging capability. While shooting, the pilot can also enable a form of cruise control to keep the sub in one place or move it at a constant speed for tracking shots - a feature many sub pilots would love to have.
To appreciably shorten dive time, its designers realized that configuring the sub with a vertical profile would enable it to speed through the water column faster than vessels with a horizontal layout. Its thrusters can power forward at 3 knots, and vertically at 2.5 knots. Prior to a dive, the Deepsea Challenger, like most deep-diving submersibles, will carry releasable ballast weights to make it negatively buoyant.
Without the weights, a large quantity (about 70 percent of the sub's total volume) of specially-designed, structural syntactic foam - essentially a durable "froth" of glass beads in epoxy resin - makes the sub very buoyant. During his dive, Cameron can feather buoyancy by releasing small quantities of shot to fine tune descent rate. The remainder of the weights are affixed to the sub by electromagnets. When he's ready to surface, in theory, he simply cuts power to the magnets, the weights drop and up he goes. Or not.
The problem with combining electronics, intense pressure and salt water is it often leads to unpredictable results. For instance, if the weights don't release, the pilot could be stranded on the bottom with little hope for rescue. If the battery powering the electromagnet fails, say, the weights will (again, in theory) drop automatically.
Should something happen to the pilot, the surface support team can beam an acoustic command to drop them. If the weights still don't drop as planned, there are even more options: galvanic timed-release wires helping to connect the weights to the sub are designed to corrode after exposure to salt water for 11 to 13 hours. Finally, Cameron can also activate a "frangibolt" system that heats and breaks the bolts holding the entire weight-drop mechanism on the sub. Awareness of the deep ocean's unforgiving nature has made the lesson clear: multiple redundancy saves lives.
Curiously, the elite group Cameron is about to join, call it, say, the Challenger Deep Club, is far more exclusive than the crowd of 500 or so astronauts who've managed to escape Earth's atmosphere. If he pulls it off later this year, he'll join Walsh and Piccard as the third man to brave the dangers and enter that abyss - a profound achievement, indeed.
Source: Deepsea Challenge via National Geographic News
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