Watching the waters: maritime domain roadmap seeks to ID all vessels.

A layered sensor network that stretches out to the deep waters of the oceans will be required to track and identify every vessel approaching U.S. shores, according to a draft of the maritime domain awareness technology roadmap obtained by National Defense.

Over the horizon radars, space-based radars and acoustic sensors are among the recommendations found in the report.

The unclassified, draft version of the roadmap is one piece in the development of the "national plan to improve maritime domain awareness," which was initiated by a national security presidential directive in December 2004. The goal is "sufficient understanding of all maritime traffic approaching U.S. shores or areas."

Data from sensors, human intelligence, and open source records must be gathered, exploited, processed, collated and interpreted, the report said.

A working group, which included representatives from 45 agencies, spent five months taking stock of the available technology, databases and potential gaps in coverage.

It focused on sensors, data fusion and how to best distribute information about vessels once they are detected.

"Every vessel must be watched in order to determine which vessels should be of interest," the report stated.

That includes everything from large oil tankers to small pleasure craft.

No one sensor is capable of doing the job. Radar, for example, can provide excellent tracking, but no identification. Electro-optical and signal intelligence sensors can provide identification capabilities, but little or no tracking information.

"The only way the problem can be solved is by using high-quality data from many sensor systems and sources to support appropriate levels of automated data fusion and data mining," the report said.

The report divided the maritime domain into six zones, with inland waterways such as rivers as Zone 0, and the high seas as Zone 5. Generally, the further out to sea the ship is, the less robust the sensor network must be, the report said. However, tracking and identifying vessels thousands of miles from U.S. shores will pose its own set of problems.

Among the technologies the working group would like to see used are:

Relocatable Over-the-Horizon Radar. ROTHR is a land-based Navy operated system that bounces high-frequency signals off the ionosphere. Energy reflected back locates sea-going targets. It has been adapted for use in counter-drug operations in the Caribbean.

Acoustic Tripwire. Although the unclassified version of the report omits details, acoustic tripwires are a series of unattended sensors that have been tested for both ground-based networks and harbor defenses. The Navy has tested a multi-influence tripwire system, which uses a series of sea-based acoustic and magnetic sensors, to detect harbor incursions.

Space-based radar. A long-time goal of the Defense Department, which is working to launch a system capable of penetrating clouds and detecting targets at night, the maritime version would be dedicated to watching the seas. "This system will be shared throughout maritime communities of interest as well as law enforcement agencies," the report said.

Fusing all these sensors will depend on the merging of "disparate, stove-piped programs," the report said. Creating a network-centric system is an issue the U.S. military has struggled with for years.

To go beyond tracking and identification, and to move into the trickier realm of determining the "intentions" of the crews manning boats, there will also have to be a vigorous human intelligence network, the report said. Resources have been severely cut back in this sector during the past decades, it added.

"A robust, effective international HUMINT network is a critical component for successful maritime domain awareness efforts, and cannot be overemphasized," the report stated.

Guy Thomas, technology advisor to the Coast Guard and one of the report's authors, said the roadmap was initially classified, but there was a consensus in the community that an unclassified version should be released so it could reach a broader audience within the government.

Many in the maritime domain awareness community believe if terrorists attempt to smuggle a weapon of mass destruction into the United States, it will not be inside a shipping container, Thomas said at an Institute for Defense and Government Advancement border management conference.

"Most of us believe it will come in a small boat."