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Sea-Based X-band (SBX) Radar

Sea-Based X-band (SBX) Radar is the tracking and discrimination radar used for the Ground-based Midcourse Defense (GMD) system. SBX will consist of a large X-Band half-populated radar mounted on a modified fifth-generation semi-submersible platform with Battle Management Command Control and Communications, which includes In-flight Interceptor Communication System Data Terminals and associated communications; power generation; facility floor space; and infrastructure, similar to a fixed radar installation.

The SBX provides detailed ballistic missile tracking information to the GMD system, as well as advanced target and countermeasures discrimination capability for the GMD interceptor missiles. The ability of the SBX to deploy to operating locations under its own power allows it to support actual GMD operations as well as realistic testing.

The SBX consists of four major operating systems: vessel; X-Band Radar (XBR); In-Flight Interceptor Communications System (IFICS) Data Terminal (IDT), and the Ground-Based Midcourse Defense (GMD) Communications Network (GCN). The vessel is a commercially designed, selfpropelled, semi-submersible oil drilling platform that was modified to meet the functional requirements of the SBX. The vessel has a dynamic positioning capability to enable precision station keeping in potential adverse sea states and weather conditions. The XBR is a phased-array system that also features a mechanical slewing capability in azimuth and elevation. The XBR operates in the X-Band portion of the frequency spectrum and represents the world's largest X-band radar. When fully integrated with the GMD system, it will become a primary midcourse discrimination sensor for Ballistic Missile Defense. X-band technology provides this midcourse sensor with the ability to perform high resolution cued search, acquisition, tracking, and target discrimination. To perform this effort, highly sophisticated algorithms are designed to enhance target acquisition and discrimination of more complex and off-nominal threat sets and targets.

The Sea-Based X-Band Radar (SBX), located aboard a platform in the Pacific Ocean, uses high-frequency and advanced radar signal processing technology to improve target resolution, permitting the radar to perform effectively against closely-spaced warheads, debris, and decoys. XBR also performs kill assessment, i.e., after impact, the XBR determines whether the actual warhead was hit and whether it was destroyed and rendered harmless.

The sea-based radar is linked to up to 10 ground based interceptors and is part of MDA's initial test bed facility. The radar was built with the capability to convert to a land-based alternative and can be upgraded if tasked to become part of an operational system.

The sea-based platform for the Test XBR is required to support the expanded test operations of the GMD component of the Ballistic Missile Defense System Test Bed. The X-Band Radar (XBR) is designed to search for, detect, and track enemy missiles, as well as determine which objects are warheads and which are decoys or debris. After inter-ception of an enemy missile, the XBR can provide an assessment of the success. MDA is currently developing and constructing a sea-based XBR for the Test Bed and initial defensive operations.

The SBX vessel, a self-propelled semi-submersible modified oil-drilling platform, was modified and payloads installed at shipyards in Brownsville and Corpus Christi, Texas. The initial sea trials took place in the Gulf of Mexico to ensure maneuverability and control of the vessel. In addition, the sea trials may include full power operation for satellite and calibration device tracking. Following the sea trials, the completed platform would transit from the Gulf of Mexico to its primary support base at Adak, Alaska. SBX performs tracking, iscrimination, and assessment of target missiles in support of missile defense tests, as well as, operation of the GMD system.

The platform is approximately 390 feet long, with a 238-foot beam, and an operations draft of approximately 75 feet. The height from water surface to the top of the radar dome is 250 feet. The deck area will be approximately 270 x 230 feet. The SBX has a displacement of 50,000 tons, and a hull weight is about 15,000 tons.

The platform has an upper deck capable to carry the top structure of the hull 20 000 tons, and is adapted for installation of the both systems of dynamic positioning and passive positioning by means of anchors, and combined system of stabilization of the platform. The design has been made to give maximum of flexibility for arrangement of alternative topsides depending on the end use of the platform; -as a drilling platform or as a floating production platform, or any other use. Thus the bare deck platform has a completely flat top deck ("main deck") on top of an enclosed double bottom structure of sufficient height to give the necessary strength for a deck load (topside weight) of about 20,000 tones.

The support vessel operations include operation the Motor/Vessel (M/V) Dove. The functions of the M/V Dove include: SBX maritime and mission equipment crew transport and transfer, fueling of the SBX, provision re-supply, transport and transfer of all equipment and hardware to and from the SBX, anchor handling, and when necessary, towing of the SBX. Logistical shore facilities are also required to support the SBX mission. There are two shore sites associated with the operations and support of the SBX: the Primary Support Base (PSB) located in Adak, Alaska (the home port for the SBX), and the Operational Support Site (OSS) located in Anchorage, Alaska. The PSB provides the functions of fuel coordination, environmental response capabilities, and is the shipping/receiving point for personnel and supplies to/from the SBX-1.

Moss CS50
Russia / USA 
Vyborg / AMFELS (Brownsville TX)
389 ft x 231 ft x 133 ft $73M 
Upper Hull -
Length of deck = 82.85 m
Breadth of deck = 70.43 m
Height to main deck = 40.65 m
Design draught at operation = 21,5/23.5 m
Displacement (tonnes) at 23.5m = 50 340 t
Design draught at transit = 9.85 m
Displacement (tonnes) = 32 800 t
Air gap operation/survival = 14.65 m / 16.65 m
Pontoons -
Length = 118.56 m
Breadth = 14.45 m
By towing = 32 800 t/9,85 m
By drilling = 49 800 t/23,5 m
Hull weight = ~ 15 000 t

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Page last modified: 21-07-2011 13:05:20 ZULU