A floating radar capable of spotting baseballs from 2,900 miles away

Countries & Cities · Published 12 October 2026 Swipe more like this →

In short: To monitor ballistic missiles over open waters, engineers built the Sea-Based X-band radar (SBX-1) as a giant floating outpost. By using a higher frequency than standard naval radars, it achieves the extreme resolution needed to distinguish actual warheads from decoys in real-time.

A twin-hulled semi-submersible oil platform of the fifth-generation CS-50 type serves as the SBX-1's base. This massive vessel, displacing 50,000 short tons, features a draft of approximately 33 feet when in motion but sinks to 98 feet when on station for stability. To maintain its position in heavy seas, the ship utilizes fully passive stabilization, keeping it within 10 degrees of horizontal. The Ground-Based Midcourse Defense (GMD) system employs it to distinguish hostile warheads from decoys while moving rapidly.

The heart of the station is a phased-array X-band radar antenna weighing 1,800 tonnes. It features 45,000 solid-state transmit-receive modules, though only about 22,000 are currently installed on its octagonal base. This configuration allows for very-long-range target discrimination. The radar's X-band frequency provides a shorter wavelength than the S-band used by Aegis systems or the C-band used by Patriot systems, enabling much finer resolution of tracked objects.

While the SBX-1 is nominally based at Adak Island in Alaska, it has spent significant time at Pearl Harbor and moves throughout the Pacific to overcome the curvature of the Earth, which limits fixed radars. Despite its capabilities, testing has raised questions regarding its ability to handle multiple targets simultaneously or report accurately to command authorities. Notably, a 2010 flight test failure was attributed to software algorithms being left disengaged rather than a hardware defect in the radar itself.

The vessel is powered by six 3.6-megawatt Caterpillar diesel generators, which provide electricity for both the radar and the electric thrusters that propel the ship at speeds of about 8 knots. Because it never points its radar at land to ensure the safety of inhabitants, it serves as a mobile sentinel in international waters.

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