compensating decrease in the need for accuracy. If 
anything, improved accuracy will be required 
because of increased operating and exploration 
costs at greater distances and in deeper water. 
Geodetic satellite programs on land are under 
way to establish a worldwide control point system 
to an accuracy of + 10 meters in an earth-centered 
coordinate system. Applications of satellite meth- 
ods to marine geodesy are under study. Satellites 
offer unique capabilities because they are inde- 
pendent of distance from shore and provide a 
singular reference datum. Current navigation by 
polar orbiting satellites requires supplementary 
methods for continuous positioning in the inter- 
vals between satellite fixes. Uncertainties in ship 
velocity and satellite orbit plus sensitivity to 
azimuth and elevation of the satellite from a ship 
are current sources of error in satellite navigation. 
Inertial navigation systems can be used to keep 
position between satellite fixes. Developments in 
navigation by geostationary satellites promise 
marked improvement through taking simultaneous 
bearings on two or more synchronous satellites 
continuously on station. 
b. Future Needs The U.S. Government may have 
to provide underwater navigation aids as it has 
such surface aids as LORAN and satellite naviga- 
tion (Figure 8). 
Figure 8. Coast Guard LORAN station at 
Nantucket, Massachusetts. Both LORAN-A and 
LORAN-C signals are transmitted from this 
station. (Coast Guard photo) 
Lack of long range, straightline communica- 
tions or sensing below the ocean surface severely 
limits subsurface navigation. The addition of 
acoustic and optical navigation aids, such as coded 
transponders, would permit periodic check of 
position. Networks of such devices would permit 
sea lanes comparable to air lanes for navigation 
and traffic control. Both surface- and bottom- 
mounted units could be used. Inertial guidance 
systems, if reduced in cost and complexity, could 
be used to extrapolate between navigation marker 
locations. 
Navigation is basic to most surface and under- 
water missions; it must be emphasized, however, 
that position determination is a fundamental 
technology that justifies advancement  inde- 
pendently of mission requirements. 
Evaluation of mission requirements for navi- 
gation support reveals that current capabilities are 
inadequate for general nonmilitary purposes. It 
further indicates that advancement of basic navi- 
gation technology, at least in part, should be 
separated from immediate mission requirements in 
order that (1) potentially useful systems not be 
shelved in favor of expediency and (2) a broader 
spectrum of instruments and information systems 
incorporating navigation input be made available. 
Broad future navigational needs range from 
precise sophisticated systems for comprehensive 
ocean surveying to simple, short range, but not 
necessarily inaccurate systems for the occasional 
boating enthusiast. 
The Department of Transportation presently is 
developing a national plan for navigation through 
the U.S. Coast Guard and Federal Aviation Admin- 
istration. The plan will consider the development 
and operation of navigation aids for current and 
future aviation and maritime commerce. It will 
identify areas of U.S. Government responsibility 
for navigation services and the current and pro- 
jected technology to carry out these responsi- 
bilities. 
2. Communications 
a. Current Status The primary communication 
link between submersibles, support ships, and 
bottom habitats is the acoustic underwater tele- 
phone. Communication is slow and difficult, par- 
ticularly when multipaths and reverberation are 
present. For short range communication links 
optical systems may be practicable. 
Transmission of submersible and station status 
and operating data by telemetry is preferable to 
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