Ever since pilot Eugene Ely watched his biplane from the forecastle of the U.S. armored cruiser USS Birmingham in 1910 -- or certainly since the commissioning of the first Lexington-class aircraft carrier in 1927 -- it's been clear: Naval air power is essential to controlling the seas.

USS Birmingham (on right) fights fire on bomb-damaged USS Princeton. Source: Wikimedia Commons

Don't get me wrong. Battleships are great for pummeling surface targets. There just not that great at swiping armed airplanes out of the sky. Submarines have their uses, too. They're nigh on invisible, for one thing. They're good at killing surface ships, and at throwing missiles at faraway targets -- but not so good at delivering air superiority.

For that matter, even aircraft carriers have their vulnerabilities. (Just ask Admiral Yamamoto). They're perversely vulnerable to enemy aircraft. In the modern world, they're also at risk of being made extinct by new weapons such as China's DF-21D "carrier killer" cruise missile.

But what if we could build a warship that offers the best attributes of all three of these kinds of vessels, but avoids their more glaring defects? A vessel that glides beneath the waves, invisible to searching eyes, capable of taking on the adversaries both below water, above water, and way above water -- even unto the sky?

Casting call for mad military scientists
That's the question that DARPA, the Defense Advanced Research Projects Agency, posed to its contractors earlier this week at a "Proposer's Day" event at Johns Hopkins University. Inviting contractors to submit ideas for a new underwater weapon system known as the "Hydra" that it's thinking about funding, DARPA has taken the first step toward building the world's first all-things-to-all-people warship.

A robotic underwater vessel, itself capable of launching robotic unmanned undersea vehicles, unmanned surface vehicles, and even unmanned aerial vehicles -- UUVs, USVs, and UAVs -- Hydra has the potential to revolutionize naval warfare in the 21st century and beyond. In a special notice to contractors published last month, DARPA described how it wants Hydra to "use modular payloads within a standardized enclosure to enable scalable, cost-effective deployment of rapid response assets."

Put more simply, what DARPA wants is an underwater aircraft carrier, a kind of mothership capable of deploying a robotic army (navy and air force) anywhere around the globe, anytime, and literally at the touch of a button.

If you can build it, DARPA will come (check in hand)
Who might build such a super vessel for DARPA? Key military shipbuilders Huntington Ingalls (NYSE:HII) and General Dynamics (NYSE:GD) are the most likely suspects, of course -- they being the two companies charged with building the nation's nuclear submarine fleet already.

But in the sphere of robotic submarines in particular, well, several companies have tried their hands at building UUVs of late. Oceaneering International (NYSE:OII) has been building remote-controlled submersibles for years. Smaller iRobot (NASDAQ:IRBT), too, has been making headway underwater with sales of its Seaglider UUV. Probably the biggest player in this nascent space, however, is Boeing (NYSE:BA), whose Echo Ranger robo-sub is already bigger than anything the competition has to offer -- and perhaps even big enough to begin scaling it up into a prototype of DARPA's Hydra.

Boeing Echo Ranger at night, Source: Boeing.

For the time being it's a work in progress, sure. But one day, one of these companies just might wind up building the future backbone of the U.S. Navy.

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