The U.S. Department of Defense’s Defense Advanced Research Projects Agency (DARPA) has completed the initial phase of its Tactical Undersea Network Architecture (TUNA) program, intended to develop concepts and technology to restore connectivity for U.S. forces when traditional tactical networks are knocked offline or otherwise available. TUNA seeks to develop and demonstrate novel, optical-fiber-based technology options and designs to temporarily restore radio frequency (RF) tactical data networks in a contested environment via an undersea optical fiber backbone. The concept involves deploying RF network node buoys—dropped from aircraft or ships—that would be connected via thin underwater fiber-optic cables. The small-diameter fiber-optic cables being developed are designed to last 30 days in the rough ocean environment—long enough to provide essential connectivity until primary methods of communications are restored. “Phase 1 of the program included successful modeling, simulation and at-sea tests of unique fiber-cable and buoy-component technologies needed to make such an undersea architecture work,” said John Kamp, program manager of DARPA’s Strategic Technology Office. “Teams were able to design strong, hair-thin, buoyant fiber-optic cables able to withstand the pressure, saltwater and currents of the ocean, as well as develop novel power generation concepts.” During the first phase of the program, the University of Washington’s Applied Physics Lab developed a unique concept called the Wave Energy Buoy that Self-deploys (WEBS), which generates electricity from wave movement for supplying power to floating buoy nodes on the open sea. The WEBS system is designed to fit into a cylinder that could be deployed from a ship or aircraft. The project enters its second and final phase for the design, implementation, testing and evaluation of the system in laboratory and at-sea demonstrations. DARPA is responsible for the development of emerging technologies for use by the U.S. military.