return precisely to it. In the case of deep drilling, MOHOLE re- 
search and development indicate that we can reenter deep-line drill 
holes if we plan in advance to do so. The MOHOLE techniques are 
good for this purpose, but are too expensive for conventional needs 
such as oil wells. 
Humble Oil Co., in the Gulf of Mexico, has demonstrated an accu- 
racy of precision in location by drilling to within a few feet of a 10- 
inch diameter pipe from a horizontal distance of 1 mile. This was 
necessary to cap a ruptured well by slant drilling and plugging with 
concrete. Although cost of surveying and guiding the drill was high, 
it was a remarkable feat of technology to do the job at all, even in 
shallow water. 
4.4. IDENTIFICATION OF OBJECTS 
In clear water under ideal conditions presently available optical im- 
age systems can give resolutions on the order of 1 inch at a range of 
150 to 3,000 feet. 
An important technological need is high-resolution imagemaking in 
turbid water. Some acoustical image systems in research today will 
not be available even as initial models for 2 or 3 years. The Panel esti- 
mates that within 10 years it will be possible to achieve resolution in 
turbid water using acoustical systems on the order of 10 feet in the 
range of 3,000 feet. While this is adequate to conduct surveillance 
under many conditions, it requires too close an approach for reconnais- 
sance and adequate identification of many important objects. Pres- 
ently there does not seem to be any good solution to the underwater 
visibility problem. What is needed is acquisition of 10-foot objects at 
1 to 5 miles with a resolution of roughly 1 foot at a mile in muddy 
water. The development of adequate acoustical imaging systems will 
require the application of the most advanced optical imaging 
techniques. 
4.5. TOOLS PROBLEM 
As yet little has been done to make available the kinds of instruments 
and tools which would change the scope and nature of work performed 
by divers on the ocean floor. Examples of such devices are: 
1. Nondestructive testing equipment to determine diagnostically 
the acceptability of components of bottom-mounted structures. A 
simple problem is reliability of a weld or porosity of a tube. 
9. Tactile manipulators which give the diver (or ultimately 
the instrument-working platform) added strength and sensing 
abilities. 
3. Semi-remote-control powered tools and support structures. 
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