Many of these anomalies were of small area and high 

 magnetic Intensity, not unlike a submarine. An ex- 

 ample is shown in Figure 2. This anomaly has a peak 

 level of almost 2000 gamma which lasts for about 2 

 minutes or 200 feet assuming the tow speed was one knot. 

 Both the leading and trailing edges are several hundred 

 gamma above ambient more than 5 minutes or 500 feet from 

 the peak. This is the type of anomaly one would expect 

 from a very large piece of metal, but it was measured 

 miles from SCORPION and identified as a pile of rocks. 



While an anomaly like that shown tends to raise 

 hopes after hours of fruitless search, it is really small 

 compared to the anomalies produced by the SCORPION. These 

 were of such a high level that the head stopped ringing. 

 At the time the first photographs of the submarine were 

 obtained, three photographs similar to Figure 3 were obtained 

 in one minute. There was no precession signal for a period 

 of five minutes and the measured magnetic intensity was well 

 above ambient for a much longer period. Though the run lasted 

 for many more hours, the magnetic measurement made the crew 

 confident that they had found the stricken submarine. Once 

 SCORPION had been located, the magnetometer proved useful in 

 maneuvering the "fish" so as to obtain more photographs. 



SONAR 



Two quite different side-looking sonar systems were used 

 in the SCORPION area with very little success. The 

 Westinghouse OBSS operated at a frequency of about 200 kHz, 

 while the NRL modified Hudson Laboratory system used a fre- 

 quency of about 30 kHz. Bottom contacts were made with both 

 systems. The example shown in Figure 4 was obtained with 

 the OBSS. The time O5IO corresponds to the peak of the mag- 

 netic anomaly shown in Figure 2. Photographs taken at this 

 time show rocks. The figure shows a number of contacts and 

 that is the difficulty. There are too many contacts^ and 

 present day systems have neither sufficient resolution to 

 determine the shape of the contact nor the ability to dif- 

 ferentiate between a steel plate and a bottom discontinuity. 

 This is unfortunate because in an underwater environment 

 sound provides greater ranges than other types of radiation. 

 In the past, most sonar systems have been developed to either 

 find the distances to the bottom or to locate a submarine 

 within the ocean volume. In order to develop a sonar system 

 which will be a useful tool for searching the ocean floor, it 

 will be necessary to find ways of obtaining greater resolution 

 and what might be called "contrast"; that is^ the ability to 

 differentiate between different solid materials. 



44 



