The military's Sea-Based X-Band Radar, otherwise known as the giant floating golf ball, is turning out to mean a lot of work for the Pearl Harbor shipyard.

The 28-story-tall radar, built atop an oil-drilling platform, will return to Hawai'i this month for maintenance and system upgrades, the Missile Defense Agency said.

The towering radar has come and gone multiple times from Pearl Harbor, sometimes as a result of sea testing and sometimes to fix problems, since it first arrived in January of 2006 from Corpus Christi, Texas, perched on a heavy-lift vessel.

Since departing Pearl Harbor in January of this year for its home base of Adak, Alaska, the radar "successfully demonstrated its ability to operate in the harsh winter weather conditions of the northern Pacific" and participated in two tests of the nation's ballistic missile defense system, the missile agency said.

The $900 million-plus radar is so powerful, officials have said, that from Chesapeake Bay it could detect a baseball-sized object over San Francisco. It is intended to track missiles in space.

The U.S. Northern Command reported in March the sea-based radar was in the northern Pacific near the Aleutian island of Adak.

The radar received a paint job and other work in Hawai'i in early 2006, and the Defense Department said at the time it would leave for Adak in March of that year.

But a leak was detected in the ballast piping before an independent review found a host of other problems on the one-of-a-kind platform, and $1.2 million in upgrades were ordered.

The radar platform may be at Pearl Harbor for several months. During that time it may go back out to sea to participate in another test of what's called the Ground-Based Midcourse Defense program, and then return to port here again.

The radar is so strong it can interfere with aircraft, automobiles and other devices that cross the beam's path. The military previously said the radar could cause "electro-explosive devices" to detonate, such as car airbags and military aircraft ejection seats.

The Missile Defense Agency said there are no plans to turn on the radar while the platform is in port. If activation becomes necessary for testing following upgrades, it would be at a low level and emit less energy than a microwave oven, officials said.

BAE Shipyards at Pearl Harbor was selected to perform the unspecified work.

Reach William Cole at wcole@honoluluadvertiser.com.