Dutch Schubert looked out her Downtown high-rise window yesterday morning and saw an enormous vessel that looked a lot like an oil rig sitting next to Aloha Tower.

Well, that's what it was — up until the mid-'90s.

Now, it's owned by Sea Launch, and the 20-story-high, 436-foot-long structure, which has large, round legs resting on two long pontoons, is used as a platform to send communications satellites into space.

It made its first-ever stop in Honolulu yesterday to refuel after a long trip in open ocean, said Sea Launch spokeswoman Paula Korn.

The vessel got in early yesterday and left for California by late yesterday afternoon. Sea Launch is based in Long Beach, Calif.

The vessel had been idling about 1,400 miles south of the Big Island since Nov. 10, waiting for strong ocean currents to subside so it could launch a communications satellite for a cell-phone company in the United Arab Emirates.

The currents never did die down, so the launch was canceled. A new launch date hasn't been scheduled.

Korn said all launches are made at the site, near the equator.

Since the company was formed in 1995, it has had 22 successful launches and two failures, not counting the mission in progress. The launch vessel, which carries the satellite rocket until it is ready for liftoff, is the only one of its kind in the world, Korn said.

"It changes the skyline wherever it is," she said.

The vessel, which was berthed at Pier 10, attracted plenty of attention from Downtown residents and passers-by. Some stopped to snap pictures of it.

Schubert, 86, asked a friend to come over and take a look.

"I've never seen anything like it before," Schubert said.

The vessel was built in 1982 as one of the world's largest oil rigs, and was used in the North Sea. It was converted into a launch platform in the mid-'90s.

The company says the ocean launch is cheaper and more reliable than a conventional satellite rocket launch on land.

Reach Mary Vorsino at mvorsino@honoluluadvertiser.com.