National Geographic : 1964 Jun
Tomorrow on the Deep Frontier large undersea features such as rock outcrops and mountains. During a search, the sonar system would include buoys anchored in a pattern perhaps 200 feet off the bottom. When the search craft sent out a "ping" of sound, each buoy would answer "pong," and the searcher would know his location by the differences in time and direction of the pings and the pongs. An inertial guidance system depends on gyroscopes, is expensive, difficult to main tain, and requires constant correction in a slow-moving craft over a long period of time. However, it is the only satisfactory method near the North and South Poles, where an ordinary compass is useless. Similar to sonar is the Doppler system-al ready in use on many airplanes and in track ing far-flying spacecraft. The vessel would bounce a sound signal off the bottom, record changes in the frequency of the returning sound waves, and thus determine forward speed and sideways drift. Combined with a good compass, this system would provide dependable navigational information. New search methods, too, are needed. The DSSRG recommends development of better magnetometers, new visual techniques that might reduce back-scatter of light, perhaps the use of blue-green lasers to pierce the wa ters with light. Better sonars and electrical potential instruments could be used to ad vantage. The search craft could even look for objects sunk in the mud by use of the sedi ment-probing "boomer" (page 786). Given our new craft, equipped with me chanical arms for work in the depths, could we raise from the bottom the hulk of a sub marine or other ship? In shallow water, yes, but no method we know of would be practical beyond the depths at which divers can work. To lift a submarine the size of Thresher,for example, might require some 200 steel cables. Surface storms or varying currents would play havoc with the complex of cables. Attaching pontoons-either rigid or in- Limp Link igloo swings above Sea Diver's deck at the Key West Naval Station. Bottles of compressed air at left will inflate the rubber house. Lead weights placed in the circular yellow collar will hold the balloonlike structure to the bottom. In March, 1964, Mr. Link was able to walk dry on the sea bottom in the air-filled igloo at a depth of 30 feet. KODACHROMESBY NATIONAL GEOGRAPHICPHOTOGRAPHERBATES LITTLEHALES (~ N.G S.