The towering Sea-Based X-Band Radar returned to Pearl Harbor Thursday for what officials said is expected to be a brief port visit.

Since the ballistic missile defense radar, topped by what looks like a giant golf ball, first arrived here in January 2006, it has returned frequently for replenishment and repairs.

In the process, Pearl Harbor has become its informal home.

About $9.4 million in work on the vessel’s thrusters and other modifications was to begin this month at Todd Shipyards in Seattle, the Missile Defense Agency previously said. Pearl Harbor is too shallow for the job.

In October the MDA said the work had to begin in March to maintain the vessel’s certificate of inspection issued by the American Bureau of Shipping.

In mid-February the MDA, which oversees the radar, announced the availability of a draft environmental assessment for public comment for the planned maintenance and repair. The MDA said repair work could begin this spring.

This marks the SBX’s 13th visit to Pearl Harbor. The 280-foot-tall SBX is tied up on the west side of Ford Island.

The MDA said that prior to this visit it had spent about $59 million for repairs and maintenance at Pearl Harbor on the $1 billion missile tracking radar.