Sea-Based X-Band radar (SBX) in Elliott Bay. (Missile Defense Agency photo.)

You may have noticed the big white ball in the Port of Seattle over the past month. It’s easily the most recognizable thing at the Port, outshining the container cranes and the ferries.

The ship is a Sea-Based X-Band Radar Vessel, and it is a sensor for the nation’s  Ballistic Missile Defense System.

The vessel is under refurbishment at Vigor Shipyard Seattle. The X-band radar is switched off while the vessel is in port. The radar dome sits atop an oil-drilling platform.

The cool thing is that it arrived in mid-May is expected to be here until mid-August, so it’s almost like it’s a part of Seafair, Seattle’s summer-long festival that celebrates the air and the sea.

When the Boeing-built X-Band Radar is on, the ship system is able to detect hostile missiles, and relay data to interceptor missiles so that the threat can be destroyed. The vessel itself is bigger than a football field and has living quarters on board.

While it is in Seattle, the U.S. Coast Guard is enforcing a “naval vessel protection zone” around the ship.

More:

• Missile Defense Agency fact sheet (PDF)
• Blogger, mom and memoirist Nicole Durbin, who has a reporter’s instinct and curiosity, took her children to try to get a closer look.
• The sensor is apparently one-of-a-kind. SeattlePI.com story.