At the beginning of the movie that made Leonardo DiCaprio a megastar, a camera-toting unmanned robot ventured into a cavernous hole in the wreck that sits on the bottom of the Atlantic, 12,640 feet from the surface. The 500-pound vehicle, christened Snoop Dog, could move only about 30 feet along a lower deck, hampered by its bulky two-inch-diameter tether hitched to a submarine that waited above. The amount of thrust needed to move its chunky frame stirred up a thick cloud. "The vehicle very quickly silted out the entire place and made imaging impossible," director James Cameron recalls.
But the eerie vista revealed by Snoop Dog on that 1995 expedition made Cameron hunger for more. He vowed to return one day with technology that could negotiate anyplace within the Titanic's interior.
In the past six months two documentaries--one for IMAX movie theaters called Ghosts of the Abyss, the other, Expedition: Bismarck, for the Discovery Channel--demonstrated the fruits of a three-year effort that Cameron financed with $1.8 million of his own money to make this vision materialize. The payoff was two 70-pound robots, named after Blues Brothers Jake and Elwood, that had the full run of two of the world's most famous wrecks, the Titanic and the Bismarck, which they visited on separate expeditions.
The person who took Jake and Elwood from dream to robot is Mike Cameron, James's brother, an aerospace engineer who once designed missiles and who also possesses a diverse background as a helicopter pilot, stunt photographer and stuntman. (Remember the corpse in the movie The Abyss, from whose mouth a crab emerges?) Giving the remotely operated vehicles freedom of movement required that they be much smaller than Snoop Dog and that the tether's width be tapered dramatically so as not to catch on vertical ship beams.
Mike Cameron took inspiration from the wire-guided torpedoes used by the military that can travel for many miles. His team created vehicles operable to more than 20,000 feet (enough to reach as much as 85 percent of the ocean floor). The dimensions of the front of the robot are 16 inches high by 17 inches across, small enough to fit in a B deck window of the Titanic. The bots have an internal battery so that they do not need to be powered through a tether. Instead the tether--fifty-thousandths of an inch in diameter--contains optical fibers that relay control signals from a manned submersible vehicle hovering outside and that also send video images in the other direction. The tether pays out from the robot, a design that prevents it from snagging on objects in the wreck.
Robots Jake and Elwood, with their 2,000-foot tethers, took on starring roles, exploring the remotest reaches of the Titanic.
James Cameron thought the project would be a straightforward engineering task, not much harder than designing a new camera system. "This turned out to be a whole different order of magnitude," he says. "There was no commercial off-the-shelf hardware that would work in the vehicles. Everything had to be built from scratch." If the team had known this early on, he added, "we wouldn't have bothered." Water pressure on the cable that carried the optical fibers could create microscopic bends in the data pipe, completely cutting off the control signals from the submersibles. Dark Matter in Valencia, Calif. (Mike Cameron's company), had to devise a fluid-filled sheath around the fiber to displace the minuscule air pockets in the cable that could lead to the microbending.
To save weight, the frame--similar to a monocoque body of a race car--was made up of small glass hollow spheres contained in an epoxy matrix. The thruster contained a large-diameter, slowly rotating blade with nozzles that diffused the propulsive flow, minimizing the churning that would otherwise disturb the caked silt. A high-resolution video camera, along with an infrared camera for navigation, was placed in the front of the craft along with three light-emitting-diode arrays for fill lighting and two quartz halogen lamps for spotlighting.