The Navy is spending billions on new submarines, building out the Virginia class of 377-foot attack boats and developing a replacement for the 560-foot Ohio ballistic missile subs. Such craft are among the world’s most advanced and complex machines; the Virginias, for example, have hulls studded with sonars and periscope-replacing masts tipped with electronic sensors.
But for all that, there remains one extraordinary gap: When they are submerged in the deep, even the most advanced subs have little more ability to communicate with the world above than did Jules Verne’s fictional Nautilus.
The seawater that veils subs from sight also blocks most radio signals. For decades, the Navy used extremely low frequencies to hail its submerged assets around the world. But since 2004, when the Navy dismantled two vast antenna arrays, it hasn’t been able to transmit instructions to any sub deeper than about 30 feet.
Today, communications means leaving the high-pressure depths where propellers churn with maximum efficiency, stealth and speed. It’s an intense time in the control room. Sonar starts seeing the surface at about 150 feet; the crew works to figure out whether there are other ships in the area. The sub must roll as quietly as possible through the waves to keep a modicum of stealth.
And there’s more bad news: The one system that sends signals tens of feet below the surface — the Fixed Submarine Broadcast System — may be getting a bit frayed.
Some Navy innovators believe there is an answer in technology. They want to give those subs connectivity via acoustics, fiber-optic tethers and maybe even lasers, but they’re receiving pushback from Navy leaders who see construction of hulls as paramount and view the comms innovations as not quite ready for prime time.
WHY IT’S HARD
The major obstacle in improving communications is the reality of electromagnetic radiation and physics. Most radio frequencies can’t penetrate the water, and those that do have long wavelengths that must be generated by huge antennas.
In 1978, after 20 years of research, the Navy solved a small part of the comms problem. The Pentagon OK’d a $283 million plan to transmit extremely low frequency, or ELF, signals that could reach subs below 400 feet, where they prefer to run. An existing test site in Wisconsin was linked with an antenna array built in Michigan, and the system went into operation.
One retired submariner who used ELF in the early 2000s said the system worked well. The messages had to be short, but that was better than waiting for the next scheduled communications link six or even 12 hours later.
But the system was dogged by public concerns. If the radiation could penetrate the deep ocean, what might it be doing to human cells? The specter of cancer was raised on the Senate floor by Sen. Russ Feingold, D-Wis., in 1998. After years of pressure, the Navy unplugged its ELF sites in 2004.
Since then, submarine communication has shifted to the very low frequency range. Subs get their messages from 10 Fixed Submarine Broadcast System sites around the world. But these signals fizzle at depths below about 30 feet, and, thanks to the massive broadcast antennas required, they can be sent only from land to subs.
Some submariners still pine for the ELF sites.
“What a marvelous bell ringer. Many of us wish they were around today,” said consultant Jim Patton, a former sub commander and technical adviser on the 1990 film “The Hunt for Red October.”
The closure of the ELF sites means there is no such bell ringer. Submarines approach the surface on regular intervals to check in.
“If you’ve got a submarine that basically was to go to point alpha but you want him to go to bravo instead, you can’t change the route because you’re on a [fixed] communications schedule,” said Patton, sometimes called the Yoda of the submarine force.
But the commander of U.S. submarine forces says the Navy is doing fine without the ELF sites.
“It’s not a problem,” Vice Adm. Michael Connor said in an interview. “We still have a very viable [concept of operations] for how we operate both our SSBNs [ballistic missile subs] and our SSNs [fast attack subs], which allows them to be connected and survivable.”
Connor dismissed any notion that communications haven’t advanced.
“If you want to do streaming video from a submarine, we can do that,” Connor said.
That’s true, but only when the sub is at the surface.
You can’t fool Mother Nature, but maybe you can work around her. Some Navy programs have examined options for better sub comms. Expendable fiber-optic tethers and buoys could be shot from subs to provide temporary satellite connectivity. Floating acoustic transmitters could pump short messages to the depths. Laser beams could send encoded data when the water is clear enough.
Until 2011, the Navy’s communications experts thought they would be deploying at least some of their innovations under a multi-million-dollar initiative called Comms at Speed and Depth. Components included:
A $35 million contract awarded to Lockheed Martin in 2009 to develop and test buoy systems. Expendable buoys were to be shot out the sub’s 3-inch signal ejector tubes, normally used to launch countermeasures. The buoys would pop up to the surface attached to fiber-optic tethers. A sub commander could keep his depth and speed and have a few minutes of satellite communications before the tether came taut and broke.
Raytheon received a $5.2 million contract in 2007 to deliver a tactical paging system called Deep Siren. Acoustic transmitters on buoys would send signals down to the subs. The subs could then come to the surface for more detailed instructions, if necessary.
Navy leaders quietly canceled Comms at Speed and Depth in 2011. Some sources blame ballooning costs.
But Connor said the ideas aren’t ready.
“The technology is not yet mature enough for us to bring it onto our ships,” he said.
Connor said his subs have the communications they need for the roles they’ve been assigned. His main concern, he said, is not the communications but maintaining adequate numbers of subs to meet demands from military commanders.
“Building two ships per year is minimizing the rate by which we get smaller as opposed to making us get bigger, if that makes sense,” he said. So, advocates for better comms are left struggling for funds against the need for more subs.
What it comes down to is that in an era of instant communications the world over, billion-dollar submarines remain the odd man out, incommunicado unless they rise to the surface. Connor said putting a mast out of the water is not a security concern.
“While that does offer an opportunity to be detected, that is still relatively undetectable compared to most other things in the water or over the water, for that matter,” he said.
When stealth is the priority — such as in a nuclear crisis — a sub can still stay 20 or 30 feet below the surface and slowly drag a very low frequency antenna. One-way emergency action messages from the president would be received that way.
Without Comms at Speed and Depth, advocates are looking for another avenue. One possible route is a plan called the Undersea Connectivity Roadmap. It’s a document describing how connectivity might be established among subs, buoys, seabed networks, unmanned underwater vehicles, surface ships and aircraft.
It comes from the same office that oversaw the aborted Comms at Speed and Depth effort.
“We’re kind of into our second year of working on this development, and we’ll look at re-engaging with our stakeholders to move it a little bit further on,” said Capt. Miguel San Pedro, manager of the Navy’s Undersea Integration Program Office in San Diego, also known as PMW 770.
San Pedro did not provide a copy, but here’s how he described the architecture outlined in the road map: “We utilize undersea unmanned vehicles. We utilize buoy gateways. We utilize seabed networks to take information, insert it, and then push it, not only to the submarine but also to surface ships.”
It’s a plan that would demand enormous bureaucratic coordination. Unlike Comms at Speed and Depth, which focused exclusively on subs, the new approach will require cooperation between multiple Navy offices.
It “moves away from the traditional submarine communication architecture, which was pretty much hub and spoke, with all communications coming to and going from the submarine,” San Pedro said.
For his part, Patton can’t believe the Navy won’t revive Comms at Speed and Depth given the Obama administration’s pivot toward the Pacific Ocean. Sixty percent of U.S. submarine forces are now operating there compared with the Atlantic. They’ll need good comms to track Chinese subs. å
Ben Iannotta is the editor of Deep Dive Intelligence (www.deepdiveintel.com).