The details of this system are beyond the scope of this report; 

 however, the system would not be too different from present positioning 

 units. The entire operation would best be done automatically, perhaps by 

 direct closed loop control of the entire positioning sequence. Areas worthy 

 of future study are the optimal command-control tradeoffs necessary to 

 determine the required data, the required calculations, and the best way to 

 generate the correct response within the available time frame. At present, 

 these factors are not adequately specified, nor can they be given a realistic 

 assessment until the type of load, the required positioning accuracy, and the 

 problem of interface coordination are analyzed. 



ALIGNMENT SYSTEMS 



In addition to mechanical systems for translating and rotating surface 

 supported loads, accurate and reliable acoustic or visual networks are needed. 

 They would supply feedback for making needed corrections in load alignment 

 during final phases of emplacement. Several concepts have been investigated, 

 including simple expedients such as manned observation (as passengers in a 

 submersible or bathysphere) to more sophisticated robot systems featuring 

 acoustic and laser targeting. 



Good visual observation at 6,000 feet is dependent on such factors as 

 water turbidity, lighting, and the sensitivity of photo-optical devices. Bottom 

 sites where sediments can be easily stirred to create clouds of slowly settling 

 debris are poor locations for the use of photo-optical devices (or the human 

 eye). 



Underwater Lighting 



Three types of light sources are commonly used in underwater 

 illumination: (1 ) the tungsten quartz iodide light, (2) the mercury vapor 

 light, and (3) the mercury-thallium iodide light. Each has advantages for 

 specific lighting tasks. The quartz iodide lamp, for example, is best for use 

 in color photography since its light output, in the yellow and red region of 

 the spectrum, tends to compensate for seawater absorption.^' The mercury 

 vapor and the mercury-thallium iodide lights, both gas discharge lamps, 

 provide much greater light output than incandescent lamps. This consideration 

 coupled with the fact that the spectral output of these light sources very 

 nearly matches the response curve of the standard vidicon tube makes them 

 ideal to use with underwater television systems (Reference 17, p. 165). 



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