Sea - based X - band Radar The Sea - Based X - Band Radar ( SBX - 1 ) is a floating , self - propelled , mobile radar station designed to operate in high winds and heavy seas . It is part of the U . S . Defense Department Ballistic Missile Defense System . The radar is mounted on a fifth generation CS - 50 twin - hulled semi - submersible drilling rig . Conversion of the vessel was carried out at the AmFELS yard in Brownsville , Texas ; the radar mount was built and mounted on the vessel at the Kiewit yard in Ingleside , Texas , near Corpus Christi . It is nominally based at Adak Island in Alaska ( though , has never put into port at Adak ) but can roam over the Pacific Ocean to detect incoming ballistic missiles . The vessel is classed by ABS and has the IMO number of 8765412 . Details . SBX - 1 is part of the Ground - Based Midcourse Defense ( GMD ) system being deployed by the MDA . Being sea - based allows the vessel to be moved to areas where it is needed for enhanced missile defense . Fixed radars provide coverage for a very limited area due to the curvature of the Earth . The primary task SBX will carry out is discrimination ( identification ) of enemy warheads from decoys , followed by precision tracking of the identified warheads . The vessel has many small radome s for various communications tasks and a central , large dome that encloses and protects a phased - array , 1 , 800 tonne ( 4 , 000 , 000 pound ) X band radar antenna . The small radomes are rigid , but the central dome is not - the flexible cover is supported by positive air pressure amounting to a few inches of water . The amount of air pressure is variable depending on weather conditions . The radar antenna itself is described as being . It has a large number of solid - state transmit - receive modules mounted on an octagonal flat base which can move ±270 degrees in azimuth and 0 to 85 degrees elevation ( although software currently limits the maximum physical elevation to 80 degrees ) . The maximum azimuth and elevation velocities are approximately 5 - 8 degrees per second . In addition to the physical motion of the base , the beam can be electronically steered off bore - sight ( details classified ) . There are currently 22 , 000 modules installed on the base . Each module has one transmit - receive feed horn and one auxiliary receive feed horn for a second polarization , so there are 44 , 000 feedhorns . The base is roughly 2 / 3 populated , with space for installation of additional modules . The current modules are concentrated towards the center , so as to minimize grating lobes . This configuration allows it to support the very - long - range target discrimination and tracking that GMD ' s midcourse segment requires . The array requires over a megawatt of power . In addition to the power consumed by the radar , the thrusters which propel the vessel are electric and require substantial power . The maximum speed is approximately . To support this and all other electrical equipment , the vessel currently has six 3 . 6 - megawatt generators ( 12 - cylinder Caterpillar diesels ) . The generators are in two compartments , one port and one starboard . The maximum power currently drawn is roughly 12 megawatts , and there are plans to expand the number of generators to eight , so that one entire compartment could be lost and the vessel would still continue to operate at full capability . The active electronically scanned array radar is derived from the radar used in the THAAD theater ballistic missile defense system , and is a part of the layered ballistic missile defense ( BMDS ) program of the United States Missile Defense Agency ( MDA ) . One important difference from Aegis is the use of X band in the SBX . Aegis uses S band , and Patriot uses the higher - frequency C band . The X band frequency is higher still , so its shorter wavelength enables finer resolution of tracked objects . The radar is designed and built by Raytheon Integrated Defense Systems for Boeing , the prime contractor on the project for MDA . The radar has been described by Lt . Gen Trey Obering ( director of MDA ) as being able to track an object the size of a baseball over San Francisco in California from the Chesapeake Bay in Virginia , approximately away . The radar will guide land - based missiles from Alaska and California , as well as in - theatre assets . The CS - 50 semi - submersible rig on which the radar is mounted was built as the " Moss Sirius " at the Vyborg Shipyard ( ) in Russia for Moss Maritime ( now part of the Saipem offshore company ) . It was purchased for the Sea - based X - band Radar project by the Boeing company , outfitted with propulsion , power and living quarters at the AmFELS shipyard in Brownsville , Texas , and integrated with the radar at the Kiewit yard in Ingleside , Texas . The first such vessel is scheduled to be based in Adak Island , Alaska , part of the Aleutian Islands . From that location it will be able to track missiles launched toward the US from both North Korea and China . Although her homeport is in Alaska , she will be tasked with moving throughout the Pacific Ocean to support her mission . The name given to the SBX vessel , " SBX - 1 , " indicates the possibility of further units of the class . In circumstances when a vessel is required to be continually on duty over a long period of time , common naval practice is to have at least three units of the type available to allow for replenishment , repair and overhaul . Three further vessels of the CS - 50 / Moss Sirius design were under construction or contract at the Severodvinsk Shipyard in Russia as of early 2007 , but were configured for oil production . On May 11 , 2011 , Col . Mark Arn , the SBX project manager for MDA , said that SBX is only one of its kind and there are no current plans for another one . In July 2011 , a Missile Defense Agency spokesman explained that other , smaller radars in the Pacific will " pick up the slack " while SBX is in port with its radar turned off . Operational history . The SBX deployed in 2006 . The ship has spent time for maintenance and repair at Pearl Harbor , Hawaii several times , including 170 days in 2006 , 63 days in 2007 , 63 days in 2008 , 177 days in 2009 , and 51 days in 2010 . When not at Hawaii , the SBX has been on operational deployments in the Pacific , including traveling to waters off Alaska . The ship has not moored at Alaska , in spite of the construction of a $ 26 million , eight - point mooring chain system installed in 2007 in Adak ' s Kuluk Bay . On June 23 , 2009 , the SBX was moved to offshore Hawaii in response to a potential North Korean missile launch . Between 2009 and 2010 , the vessel spent 396 continuous days at sea . The SBX failed during a flight test on January 31 , 2010 , designated FTG - 06 . The test was a simulation of a North Korean or Iranian missile launch . The test failure arose from two factors , the first being that algorithms in the SBX radar software which are designed to filter out extraneous information from the target scene were left disengaged for the test , and the second was a mechanical failure in a thruster on the kill vehicle . During flight test FTG - 06a on December 15 , 2010 , the SBX performed as expected , but intercept of the target missile was again not achieved . In May 2011 , the SBX - 1 entered Vigor Shipyard ( formerly the Todd Pacific Shipyard ) in Seattle for a $ 27 million upgrade and maintenance work by contractor Boeing . The work was completed in about three months and in August 2011 , SBX - 1 departed Seattle for deployment . In February 2012 , the Missile Defense Agency requested only $ 9 . 7 million per year for Fiscal Years 2013 through 2017 , down from $ 176 . 8 million in fiscal 2012 . This reduced amount would be used to maintain SBX in a “ limited test support ” role , " while also retaining the ability to recall it to an active , operational status if and when it is needed . ” In April 2012 it was reported that SBX - 1 had left Pearl Harbor and was assumed to be being deployed to monitor North Korea ' s planned Unha - 3 missile in the launch window of 12 – 16 April 2012 . The vessel returned to Pearl Harbor on 21 May 2012 . It redeployed to monitor the next North Korean launch attempt at the end of 2012 . In April 2013 it was reported that SBX - 1 was being deployed to monitor North Korea . References . Sea - Based X - band Radar ( SBX ) vessel entered Elliott Bay Tuesday night http : / / www . westseattleherald . com / 2011 / 05 / 10 / news / slideshow - update - 3 - sea - based - x - band - radar - sbx - ves Sea Based X - Band Radar ( SBX ) vessel up close and personal at Vigor Shipyard http : / / www . westseattleherald . com / 2011 / 05 / 11 / news / sea - based - x - band - radar - sbx - vessel - close - and - perso