Washington — President Reagan has approved construction of a communications system that will allow US submarines to receive signals from the Pentagon at greater depths than before, thus reducing their vulnerability to attack from Soviet planes and warships.
"Any submariner will tell you, you never want to be near the surface," says Capt. Daniel E. Donovan, deputy director of naval communications, briefing reporters about the extremely low frequency (ELF) system which will be located in Wisconsin and the upper peninsula of Michigan.
The system, which is to cost $230 million and enter service in 1985, consists of a pair of transmiters and miles of cable slung from telephone poles. Both ends of each antenna are electrically grounded.
Current from the transmitter is driven out from one end of the cable deep through the earth to the other end, to create a closed loop from which the resulting ELF radio waves are propagated to submarines patrolling several hundred feet beneath the sea.
The "uniquely low conductivity" of the granite underlying the ELF deployment area (which is part of what geologits call the Laurentian Shield), gives the submarine communication system added effectiveness, explains Captain Donovan.
When confronted with a poor conductor, the current, injected into the ground at one end of the giant antenna of cable, is forced to plunge deeper into the earth to find a conductive layer of rock by which it can return to the other end. In doing this it creates a larger loop and thus extends the range of ELF communications. Even with this assitance from the Laurentian Shield, the ELF system will only be able to reach into the North Pacific and North Atlantic.
Moreover, because it is only designed to transmit what Captain Donovan likens to "flag hoist" messages of a short tactical nature, it cannot relay the more lengthy "Doomsday" targeting and firing data to ballistic missile submarines. Those on alert are still required to remain on or near the surface to receive such information. Only a system "hundreds of times" bigger would be capable of such a feat, says Captain Donovan, deeming the necessary construction neither militarily nor environmentally feasible.
Nevertheless, the ability of the ELF system to transmit messages some 400 feet beneath the waves accords submarines a far greater degree of protection than they previosly enjoyed when they were forced to approach or break the surface to get their instructions. According to columnists Rowland Evans and Robert Novak, the submarine USS George Washington was ascending to a shallow depth in the East China Sea to communicate with shore commanders April 10 when it collided with a Japanese freighter, drowning the freighter's captain and one crewman.
All submarines --ballistic missile and attack -- will be able to make use of the ELF communication system. But only 20 subs initially will be fitted with receivers, the bulk of these being strategic missile boats, according to Captain Donovan. He adds that the ELF system will be "highly resistant" to Soviet jamming.
The ELF program calls for upgrading, but not enlarging, an existing research and development transmitter together with a 28-mile-long cable antenna at Clam Lake, Wisc. A second tramsmitter with a 56-mile antenna will be built in state forests south of K. I. Sawyer Air Force Base in Michigan, says the Defense Department.
The Navy has been trying for some 20 years to construct a system that can communicate with submarines at relatively deep depths. Its first scheme, code-named Sanguine, required the burying of 4,000 mile sof cable near Clam Lake but was axed in 1973 by Defense Secretary Melvin Laird after protest groups complained that its radio waves would wreak havoc with the environment. The project, which resurfaced as Seafarer in 1975, was designaed ELF in 1978.
Even though the currently proposed system is much smaller than originally conceived, opposition is expected from both congressional and environmental groups.
"ELF is an outmoded and ineffective scheme," declared Sen. Carl Levin (D) of Michigan, a member of the Senate Armed Services Committe, last week. Vowing that he would try to block "wasteful expenditure of public funds" for the project, he claimed that its signals "can only reach submarines moving at restricted speeds and in certain directions."
Sen. Donald W. Riegle Jr. (D) of Michigan added that the long battle against the project will continue "at every step of the congressional process."
Captain Donovan; a former submarine commander, believes that reaction to the proposed ELF system in Wisconsin and Michigan will be "emotional," but contends that i f local leaders support it, those living near the sites will accept it readily enough.
He recommended that the possbility of using laser beams to communicate with submarines be explored as the ELF system is installed. Reportedly the Navy and the Defense Advanced Research Projects Agency already have begun to examine the feasibility of employing laser beams to perform such a function. Laser signals can carry a far greater volume of information than ELF transmissions, say experts.
Two systems are said to be under study: one would flash a message to a satellite, which would retransmit it by laser to a submarine. The other involves beaming a ground-based laser to a satellite-borne reflector, which would then beam it to the submarine.