ANOTHER LEAGUE UNDER THE SEA

Transcription

1 concepts & Prototypes where tomorrow s technology begins ANOTHER LEAGUE UNDER THE SEA ARMED WITH BETTER BATTERIES AND STRONGER MATERIALS, NEW SUBMERSIBLES AIM TO GO DEEPER THAN EVER BEFORE AND OPEN THE WHOLE OF THE UNEXPLORED OCEAN TO HUMAN EYES BY ABE STREEP by liberal estimates, we ve explored about 5 percent of the seas, and nearly all of that in the first 1,000 feet. That s the familiar blue part, penetrated by sunlight, home to the colorful reefs and just about every fish you ve ever seen. Beyond that is the deep a pitch-black region that stretches down to roughly 35,800 feet, the bottom of the Marianas Trench. Nearly all the major oceanographic finds made in that region hydrothermal vents and the rare life-forms that thrive in the extreme temperatures there, sponges that can treat tumors, thousands of new species, the Titanic have occurred above 15,000 feet, the lower limit of the world s handful of manned submersibles for most of the past 50 years. Now engineers want to unlock the rest of the sea with a new fleet of manned submersibles. And they don t have to go to the very bottom to do it. In fact, only about 2 percent of the seafloor lies below 20,000 feet, in deep, muddy trenches. If we extend our current reach just 5,000 feet another mile it will open about 98 percent of the world s oceans to scientific eyes. The payoffs could be huge. Mining companies hope to search hydrothermal vents for minerals like nickel; gas and oil companies are eager to explore the seafloor for new energy sources; and marine biologists want to study how climate change has affected deep ecosystems. In addition, there s simple curiosity of the man-versusnature sort. With all the world s highest peaks summited and both poles trampled, the deep seas are a ripe frontier. But sending a vehicle that deep requires serious cash and engineering. The craft must be small enough to move on battery power and sturdy enough to withstand immense pressure 10,340 pounds of water per square inch at 23,000 feet, equivalent to having a school bus on your head. A manned submersible has to meet even higher standards: It must keep its occupants alive. In 1960, American naval lieutenant Don Walsh and Swiss engineer Jacques Piccard made the only expedition to the world s deepest point, piloting a 50- foot, submarine-like vehicle called the NICK KALOTERAKIS

2 FLYING LOW The Deep Flight II sub uses stubby wings that propel it down like an airplane goes up.

3 CONCEPTS & PROTOTYPES Bathyscaphe Trieste 35,800 feet down to the bottom of the Marianas Trench. They spent 30 minutes on the bottom of the world before surfacing with their glass viewing ports cracked by the pressure. No one has been back since. And should they? There s a heated debate among oceanographers over whether the next generation of deep exploration should be performed by robots, humans or both. The argument for remotely operated vehicles (ROVs) is led by oceanographer Robert Ballard, who gained fame in manned subs, discovering the first hydrothermal vents and exploring the wreck of the Titanic. His case is simple: With no power-sucking life-support systems, ROVs offer more time on the ocean floor and therefore, more opportunity to explore what we don t know than manned subs. The robots send high-definition images and video to a ship by fiber-optic cable. The ship then sends the data via high-speed fiber-optic lines the Japanese Shinkai 6,500, the world s deepest-diving sub, which is capable of descending to 21,000 feet. (The Chinese government is reportedly working on a similar sub that would reach 23,000 feet.) These vehicles all function in a similar manner. A support ship drops the vessel overboard. Anchored with weights, the sub begins to sink. To do some exploring in the middle depths, the pilot cuts some of the weight and the vehicle hovers, pumping water in or out to achieve a weight equal to that of the surrounding sea. Battery-powered motors propel the craft laterally for a short time, the ballast system takes on more water, and the craft sinks to the bottom. After scientists explore the seafloor and pick up samples with robotic arms, the pilot cuts the remaining anchors, and the sub surfaces. This elevator-like model works, but because the vehicles house people, electronics and motors within pressure- imagine exploring all of africa with only five jeeps. to a series of command centers, where oceanographers can analyze results in real time. I m interested in bottom time, not the spiritual experience of diving, Ballard says. Others argue that collecting samples from the seafloor is easier when a person is in the pilot s seat, and that no machine can replicate the panoramic scope of human vision. In 2004, celebrated oceanographer Sylvia Earle was in a sub 1,400 feet deep off the Florida Keys when, out of the corner of her eye, she spotted a six-foot mola mola, an ocean sunfish previously thought to live only near the surface. Earle is the most prominent of many advocates for manned research, and she boils her case down to a neat metaphor: Would you send a robot to taste wine in Paris? THE COMING SUBS Today only five manned subs can dive to 15,000 feet: the French Nautile; two Russian submersibles; Woods Hole s Alvin, which Ballard used to explore the Titanic; and resistant, spherical titanium hulls, they re heavy Alvin weighs about 36,000 pounds and require enormous support ships. And because of the limitations of battery technology, traditional submersibles don t give scientists much time on the seafloor; the Alvin s current floor time is four hours. As a result, manned deep-sea exploration is incredibly inefficient. Imagine exploring all of Africa with only five Jeeps. But new technology is changing the way designers look at submersibles. In 2008, engineers at Woods Hole announced plans for a $21-million renovation of the Alvin that would upgrade the viewing sphere and sample-collecting systems, allow for more maneuverability, and enable the vehicle to travel to 21,000 feet (the Alvin now maxes out at 14,760 feet). In addition to a new titanium alloy that can withstand greater pressure yet weighs less [see The Science Sub, facing page], the key to the renovation [CONTINUED ON page 37] THE ANNOTATED DEEP Where the human body implodes, and more milestones on the way to the bottom of the ocean Surface The weight of air exerts an imperceptible 14.7 pounds per square inch (psi) in all directions 33 feet Exactly double the pressure at sea level. Even with a snorkel that reached the surface, the pressure on your body is too great to take a breath. 500 feet Even with scuba gear, this is where most divers start to experience high-pressure neurological syndrome, which causes headache, tremors and muscle twitching. Nerves can t adapt to the increased pressure and malfunction. 702 feet The free-dive record (no scuba gear), set by Austrian diver Herbert Nitsch in At this depth, his lungs were almost 95 percent collapsed and the rest filled with blood plasma. 1,044 feet The depth at which South African diver Nuno Gomes set the scuba-dive record in Gomes was convulsing so badly that the respirator was coming loose from his mouth. 1,500 feet Specific depths are classified, but nuclear attack subs typically operate in this territory. 6,500 feet Target depth for one of three versions of Deep Flight II Graham Hawkes hopes to sell. He also plans to offer a model that will reach 22,000 feet, and another capable of full-ocean depth. 12,500 feet Resting place of the RMS Titanic, which sunk in ,000 feet Target maximum depth for the new Alvin, after final upgrades in ,800 feet At this depth, the pressure is more than 1,100 times that of the surface, or over 15,000 psi. Only two people have ever reached this depth, in 1960 in the Trieste. The window began to crack, so the recordsetting trip was cut short after just 30 minutes on the bottom. 34 POPULAR SCIENCE AUGUST 2009

4 The Science Sub A new Alvin sub a complete $21-million retooling of the 45-yearold workhorse of deep-sea research should be complete by 2015, with a new body and lighter batteries that will let it go deeper (21,000 feet), stay down longer (10 hours), and rise 50 percent faster, at 1.78 miles an hour. Marshall louis Reaves Lights Ten bundles of LED lights will illuminate the deep five times as efficiently as the previous bulbs and last four times as long five years or more. Each lamp can be precisely controlled to provide even, focused light for the researchers and high-definition cameras. Body The body is kept afloat by a material called syntactic foam, which consists of billions of tiny air-filled glass spheres embedded in an epoxy resin, like hardened Styrofoam. Syntactic foam has been used in oil rigs and diving equipment, but Alvin will employ a new version that combines two different sizes of glass spheres, which means they fit together more closely, for an unprecedented strength-to-weight ratio. Thrusters Six electric thrusters let the craft move in any direction. The typical range is only a few hundred yards, but if there s nothing else being powered by the batteries, Alvin could travel up to two miles. PETER BOLLINGER Robotic arms The new Alvin gets a more powerful and agile set of robotic arms, and its basket can carry up to 400 pounds of equipment or samples to and from the surface. Its tool arsenal includes sensors for measuring thermal vents and coring devices for sampling sediments. Sphere Forged from a strong yet lightweight titanium alloy, the seven-foot-diameter crew sphere is machined with exacting precision. Discrepancies of even 1 /50 of an inch from a perfect sphere could cause a structural collapse under the intense pressure of the deep ocean. Viewports Five viewports two more than the current sub and, at more than a foot across, several inches larger let researchers view wider swaths of the deep through nearly four inches of Plexiglas. The new array lets the pilot look left and right from the driver s seat without getting up. Ballast Steel weights carry Alvin toward the bottom. A ballast system adjusts buoyancy once it reaches the bottom and unloads some of its equipment, releasing air from fiberglass tanks to help it stay down. To ascend, the pilot just releases the steel weights. batteries The biggest upgrade is a cadre of lithiumion batteries, which provide twice the power at half the weight of the old lead-acid batteries. They will enable dives of more than 10 hours (five hours longer than today s Alvin) and a top speed of three knots, up from the current two. STATS ALVIN SIZE: 24 ft. long x 9 ft. wide x 12 ft. high (est.) WEIGHT: 20 tons OPERATING TIME: 10.5 hrs. CREW: 1 pilot, 2 researchers MAX. DEPTH: 21,000 ft. (by 2015) VERTICAL SPEED: 157 ft./min. POPSCI.COM POPULAR SCIENCE 35

5 CONCEPTS & PROTOTYPES The Underwater Plane Graham Hawkes wants to create a comparatively affordable deep-sea sub that s light enough to launch from a yacht and easy to drive, opening the depths to an army of private explorers. His winged craft will operate solo or in pairs and travel miles along the seafloor. m.l.r. Cockpit The pilot, strapped in stomach-down, can steer the craft using a joystick to control the wings. The prone position mirrors the natural posture of divers and fish and puts the pilot s eyes as close as possible to the viewport and the robotic arms. It also minimizes the size of the pressurized chamber, which reduces the craft s weight to just 5,000 pounds. Batteries Hawkes is using the latest lithium-ion batteries, known as lithium-polymer. Their housing is pressurized to help with buoyancy. Body materials Developed by the U.S. Navy and refined by Hawkes s team, the composite ceramics of the body tout a higher strengthto-weight ratio than titanium. The body surrounds the pressurized hull and other equipment, like the battery cells. Thrusters In a work configuration, four pairs of lateral and hovering electric thrusters five-bladed propellers allow for careful maneuvers near the seafloor, stabilizing the craft within fractions of an inch for hovering against cliff faces. Configured for sightseeing, two high-speed thrusters propel the sub forward at 600 feet per minute. Wings Two stubby wings allow the sub to fly underwater in any direction. Rather than slowly sinking or rising like a blimp, the craft uses water running past its wings to create reverse lift the opposite of the force on an airplane s wings and moves up or down depending on the position of the flaps. It can dive 400 feet per minute, four times as fast as current subs. Lights and Cameras Wing- and nosemounted LED lamps let the pilot and the onboard highdefinition cameras see 40 feet into the inky black. Lasers probe the water for obstacles ahead, while low-intensity sonar scans the water for creatures so the pilot can quickly turn on the lights and snap a photo before the animal darts away. Hull A cylindrical compartment needs to be twice as strong as a spherical one because of the way the pressure is distributed over the surface of the pressurized hull. Hawkes is using a special kind of carbon composite, originally developed for aerospace applications like rocket nozzles, that better resists compression than standard carbon fiber, which is best at resisting tearing. Traditionally, carbon fiber is made with an interwoven pattern that makes for weak spots where the fibers overlap. To make the new material, a computer lays each braided, hair-size fiber alongside the next. The carbon composite is lighter than titanium, which aids buoyancy. STATS DEEP FLIGHT II SIZE: 16 ft. long, 4.5 ft. wide, 4 ft. high WEIGHT: 5,000 lbs. OPERATING TIME: 8 hrs. CREW: One- and twoperson configurations MAX. DEPTH: Initially 6,500 ft., eventually 35,800 ft. VERTICAL SPEED: 500 ft./min. ascent, 400 ft./min. descent 36 POPULAR SCIENCE AUGUST 2009

6 COURTESY CHRISTOPHER GRINER/WOODS HOLE OCEANOGRAPHIC INSTITUTION; FACING PAGE: NICK KALOTERAKIS [CONTINUED FROM page 34] is rapidly evolving lithium-ion battery technology. Lithium-ion will give Woods Hole engineers a battery that s lighter than the current lead-acid version and capable of delivering twice as much power, which would mean more time spent moving laterally in the water and powering instruments on the seafloor. Because of a funding shortage, renovation is scheduled to happen in two stages. (Oceanographers like to point out that NASA s budget this year is $17.6 billion, while the National Science Foundation, which doles out money to Woods Hole, has been allotted only $330 million for ocean research.) The first stage, an upgrade of the battery and the personnel sphere, should be completed by But the Alvin won t increase its maximum depth until the second stage, optimistically scheduled for Then there s Graham Hawkes, the founder of Hawkes Ocean Technologies, a company that designs aircraft-like submersibles. The English-born engineer (and Earle s ex-husband) sums up the situation a little more brashly. In a couple of centuries they ll finally realize that this is an ocean planet, and there will be a great era of ocean exploration, he says. They re going to build a great craft, go down to the seafloor, and they ll find a little plaque. It will say, Hawkes was here. Hawkes s goal is to open the deep seas to anyone able to pay a few million dollars for a small sub. His model, both in a business and engineering sense, is the private jet. His submersible designs have fixed wings and sleek, elongated fuselages, like those on an aircraft. The pilot sits in a small, pressure-resistant hull. Everything else, including the motors, electronics and the lightweight foam that buoys the vehicle, is housed outside the hulls in the fuselages, saving weight. The sub is positively buoyant lighter than the water it travels through. Its wings are inverted, and electric thrusters keep the craft from floating to the surface. Just as an airplane needs upward thrust to lift off, Hawkes s subs use downward thrust to descend. Hawkes recently completed a shallowwater submersible, the 4,000-pound Super Falcon (price tag: $1.5 million), which can reach 1,000 feet and uses the flying-craft The Deepest Diver On May 31, an unmanned submersible called Nereus became only the third craft ever to reach the full depth of the Marianas Trench, 35,770 feet below sea level. Built by the Woods Hole Oceanographic Institution, the sub is a hybrid of a remotely operated vehicle (ROV) and autonomous underwater vehicle (AUV). The Nereus runs on its own battery power, but researchers on a mother ship send it commands over a single hair-thin fiber-optic line that s 25 miles long but weighs just 5.6 pounds. The traditional ROV tether consists of steel-jacketed cables on enormous spools. By using a battery-powered ROV coupled with a single optical fiber, we get the best of both worlds, says Chris German, Woods Hole s chief scientist for deep submergence. The cable also carries back photos and real-time video, which the operators use to direct the robotic arm, biological samplers and sensors. Because the craft is far more nimble than traditional ROVs, researchers hope to use it in other hard-to-reach places, like ice-covered seas. The fiber-optic tether technology could also find its way onto future manned ships, preserving their freedom while allowing real-time communication with the mother ship above. design. But building a lightweight deep-sea sub is a much bigger challenge. Hawkes says he has solved this problem with tough ceramic-metal composites and a pressureresistant lithium-ion battery system. Four years ago, he started building a deep-sea vehicle, the 8,000-pound Challenger, for adventurer Steve Fossett, who planned to dive to the bottom of the Marianas Trench. During pressure tests at Penn State University s Applied Research Lab, the vehicle s glass viewing sphere cracked as a result of what Hawkes calls a manufacturing flaw with a machined titanium part adjacent to the sphere. After Fossett s death in a private-plane crash in 2007, Hawkes stopped working on the Challenger (Fossett s widow now owns the original machine) and turned his attention to the Super Falcon. With that vehicle now on the market, Hawkes s goal is to apply what he learned on the Challenger project to create a new commercial sub, called Deep Flight II, that will move freely through the ocean at any depth. The Challenger used a dropweight system similar to the Alvin s to assist its descent. Deep Flight II will ideally replace the weights with a stronger lithium-polymer battery, so its thrusters can propel it down, making it more nimble in the water. Even if Hawkes builds his vehicles in the next two years, as he hopes to, such crafts would probably be too small to haul a lot of scientific instruments. The Alvin is clunky, but it can carry many video cameras and monitors in its viewing hull. The negligible trunk space on his vehicles contributes to the idea aired in some scientific circles that Hawkes makes stunt subs. Hawkes says those criticisms are based on outdated notions. Instruments like cameras are becoming smaller and more efficient, he points out, and Deep Flight II subs will have robotic arms. Whatever criticism it receives, a craft like Hawkes s would be a huge boon to marine biologists, who are restricted to using vehicles like Alvin for mostly immobile observation. Deep Flight II would allow scientists to rove freely. Alvin is a wonderful vehicle for exploring the deep seafloor, says Bruce Robison, a marine biologist at the Monterey Bay Aquarium Research Institute in California, but it can t work effectively in that middle depth where most of the animals are. We haven t had many vehicles capable of working as freely in the ocean as the animals that live there. Ultimately, there s room for a mix of government-sponsored research vessels and private explorers in craft like Hawkes s charting new underwater territory. After all, there s a lot of area to cover. The oceans make up two thirds of the planet, and they re unexplored, Hawkes says. We want to find out what we don t know. Abe Streep wrote about personal helicopters for POPULAR SCIENCE last November. POPSCI.COM POPULAR SCIENCE 37